为了提高代码的封装性及可读性，我把原来手懒搞的一些AsyncTask的继承内部类决定都单独拉到一个文件夹中，但这一拉，出事情了！
我的应用业务是，有一个min_question_id(int )来记录目前读取到的服务器端数据，原来是内部类的时候，用的好好的，这把它单独剥离出来，每次拉取数据却是从头拉取了！
好了，先上原来的代码！
public class getQuestionListDataTask extends AsyncTask<Void, Void, Void>{ private static final int GETREFRESUCCESS=5000; private static final int GETREQUESTERROR=5001; private static final int DATASETEMPTY=5002; PullToRefreshListView mPullToRefreshLayout; List<HashMap<String, Object>> listItemQuestion; boolean isFirstEnter; int min_question_id; QuestionListAdapter mQuestionListAdapter; /* * mpPullToRefreshListView:异步刷新工作对应的PullToRefreshListView * mList:PullToRefreshListView对应的后台数据引用 * isfirstEnter:记录是否第一次开机后第一次进入app * min_question_id:获取问题列表时候的最小id * mQuestionListAdapter:驱动mpPullToRefreshListView的适配器 */ public getQuestionListDataTask(PullToRefreshListView mPullToRefreshListView,List<HashMap<String, Object>> mList, booleanisfirstEnter,int min_question_id,QuestionListAdapter mQuestionListAdapter) { super(); this.mPullToRefreshLayout=mPullToRefreshListView; this.listItemQuestion=mList; this.isFirstEnter=isfirstEnter; this.min_question_id=min_question_id; this.mQuestionListAdapter=mQuestionListAdapter; } @Override protected Void doInBackground(Void... arg0) { // TODO Auto-generated method stub if(mPullToRefreshLayout.isHeaderShown()) { listItemQuestion.clear(); getQuestionListData(0, true); isFirstEnter=false; } if(mPullToRefreshLayout.isFooterShown()) { getQuestionListData(min_question_id,false); } else { listItemQuestion.clear(); getQuestionListData(0, true); //getHttpData(min_question_id,false); } return null; } @Override protected void onPostExecute(Void result) { // TODO Auto-generated method stub mQuestionListAdapter.notifyDataSetChanged(); mPullToRefreshLayout.onRefreshComplete(); super.onPostExecute(result); }}里面的getQuesionListData是一个拉取网络数据的接口，由于大家都懂的的原因，我就不贴出来啦~~我的要求是每一次拉取完数据(实例化一次getQuesionListDataTask并执行)，都在getQuesionListData更新min_question_id的值。
显然，数据每次都还从头拉的原因就是这个min_question_id并没有得到更新！
java的传递不是值传递吗？！
是吗？！不是，这只是我的一个误区。
①基本类型变量，包括char、byte、short、int、long、float、double、boolean 。
②非基本变量。
而非基本变量是引用传递，基本变量是值传递！
那怎么办呢？难道我们要把char、byte、short、int、long、float、double、boolean这些东西自己写个wrapper把它们wrap成类？却是是这样的！但是我们不用自己写，java自身就带有这些包，就是这些基本类型的包装类！
分别和上面基本变量类型对应的是：Character，Byte，Short，Integer，Long，Float，Double，Boolean。
而且支持自动wrap/unwrap，妈妈再也不用担心我的手指了！
但是，别高兴的过早！让我们看一眼Integer的源码：
/* * %W% %E% * * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved. * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */package java.lang;import java.util.Properties;/** * The <code>Integer</code> class wraps a value of the primitive type * <code>int</code> in an object. An object of type * <code>Integer</code> contains a single field whose type is * <code>int</code>. * * <p> * * In addition, this class provides several methods for converting an * <code>int</code> to a <code>String</code> and a <code>String</code> * to an <code>int</code>, as well as other constants and methods * useful when dealing with an <code>int</code>. * * <p>Implementation note: The implementations of the "bit twiddling" * methods (such as [email protected] #highestOneBit(int) highestOneBit} and * [email protected] #numberOfTrailingZeros(int) numberOfTrailingZeros}) are * based on material from Henry S. Warren, Jr.'s <i>Hacker's * Delight</i>, (Addison Wesley, 2002). * * @author Lee Boynton * @author Arthur van Hoff * @author Josh Bloch * @version %I%, %G% * @since JDK1.0 */public final class Integer extends Number implements Comparable<Integer> { /** * A constant holding the minimum value an <code>int</code> can * have, -2<sup>31</sup>. */ public static final int MIN_VALUE = 0x80000000; /** * A constant holding the maximum value an <code>int</code> can * have, 2<sup>31</sup>-1. */ public static final int MAX_VALUE = 0x7fffffff; /** * The <code>Class</code> instance representing the primitive type * <code>int</code>. * * @since JDK1.1 */ public static final Class<Integer> TYPE = (Class<Integer>) Class.getPrimitiveClass("int"); /** * All possible chars for representing a number as a String */ final static char[] digits = { '0' , '1' , '2' , '3' , '4' , '5' , '6' , '7' , '8' , '9' , 'a' , 'b' , 'c' , 'd' , 'e' , 'f' , 'g' , 'h' , 'i' , 'j' , 'k' , 'l' , 'm' , 'n' , 'o' , 'p' , 'q' , 'r' , 's' , 't' , 'u' , 'v' , 'w' , 'x' , 'y' , 'z' }; /** * Returns a string representation of the first argument in the * radix specified by the second argument. * <p> * If the radix is smaller than <code>Character.MIN_RADIX</code> * or larger than <code>Character.MAX_RADIX</code>, then the radix * <code>10</code> is used instead. * <p> * If the first argument is negative, the first element of the * result is the ASCII minus character <code>'-'</code> * (<code>'\u002D'</code>). If the first argument is not * negative, no sign character appears in the result. * <p> * The remaining characters of the result represent the magnitude * of the first argument. If the magnitude is zero, it is * represented by a single zero character <code>'0'</code> * (<code>'\u0030'</code>); otherwise, the first character of * the representation of the magnitude will not be the zero * character. The following ASCII characters are used as digits: * <blockquote><pre> * 0123456789abcdefghijklmnopqrstuvwxyz * </pre></blockquote> * These are <code>'\u0030'</code> through * <code>'\u0039'</code> and <code>'\u0061'</code> through * <code>'\u007A'</code>. If <code>radix</code> is * <var>N</var>, then the first <var>N</var> of these characters * are used as radix-<var>N</var> digits in the order shown. Thus, * the digits for hexadecimal (radix 16) are * <code>0123456789abcdef</code>. If uppercase letters are * desired, the [email protected] java.lang.String#toUpperCase()} method may * be called on the result: * <blockquote><pre> * Integer.toString(n, 16).toUpperCase() * </pre></blockquote> * * @param i an integer to be converted to a string. * @param radix the radix to use in the string representation. * @return a string representation of the argument in the specified radix. * @see java.lang.Character#MAX_RADIX * @see java.lang.Character#MIN_RADIX */ public static String toString(int i, int radix) { if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX) radix = 10; /* Use the faster version */ if (radix == 10) { return toString(i); } char buf[] = new char[33]; boolean negative = (i < 0); int charPos = 32; if (!negative) { i = -i; } while (i <= -radix) { buf[charPos--] = digits[-(i % radix)]; i = i / radix; } buf[charPos] = digits[-i]; if (negative) { buf[--charPos] = '-'; } return new String(buf, charPos, (33 - charPos)); } /** * Returns a string representation of the integer argument as an * unsigned integer in base 16. * <p> * The unsigned integer value is the argument plus 2<sup>32</sup> * if the argument is negative; otherwise, it is equal to the * argument. This value is converted to a string of ASCII digits * in hexadecimal (base 16) with no extra leading * <code>0</code>s. If the unsigned magnitude is zero, it is * represented by a single zero character <code>'0'</code> * (<code>'\u0030'</code>); otherwise, the first character of * the representation of the unsigned magnitude will not be the * zero character. The following characters are used as * hexadecimal digits: * <blockquote><pre> * 0123456789abcdef * </pre></blockquote> * These are the characters <code>'\u0030'</code> through * <code>'\u0039'</code> and <code>'\u0061'</code> through * <code>'\u0066'</code>. If uppercase letters are * desired, the [email protected] java.lang.String#toUpperCase()} method may * be called on the result: * <blockquote><pre> * Integer.toHexString(n).toUpperCase() * </pre></blockquote> * * @param i an integer to be converted to a string. * @return the string representation of the unsigned integer value * represented by the argument in hexadecimal (base 16). * @since JDK1.0.2 */ public static String toHexString(int i) { return toUnsignedString(i, 4); } /** * Returns a string representation of the integer argument as an * unsigned integer in base 8. * <p> * The unsigned integer value is the argument plus 2<sup>32</sup> * if the argument is negative; otherwise, it is equal to the * argument. This value is converted to a string of ASCII digits * in octal (base 8) with no extra leading <code>0</code>s. * <p> * If the unsigned magnitude is zero, it is represented by a * single zero character <code>'0'</code> * (<code>'\u0030'</code>); otherwise, the first character of * the representation of the unsigned magnitude will not be the * zero character. The following characters are used as octal * digits: * <blockquote><pre> * 01234567 * </pre></blockquote> * These are the characters <code>'\u0030'</code> through * <code>'\u0037'</code>. * * @param i an integer to be converted to a string. * @return the string representation of the unsigned integer value * represented by the argument in octal (base 8). * @since JDK1.0.2 */ public static String toOctalString(int i) { return toUnsignedString(i, 3); } /** * Returns a string representation of the integer argument as an * unsigned integer in base 2. * <p> * The unsigned integer value is the argument plus 2<sup>32</sup> * if the argument is negative; otherwise it is equal to the * argument. This value is converted to a string of ASCII digits * in binary (base 2) with no extra leading <code>0</code>s. * If the unsigned magnitude is zero, it is represented by a * single zero character <code>'0'</code> * (<code>'\u0030'</code>); otherwise, the first character of * the representation of the unsigned magnitude will not be the * zero character. The characters <code>'0'</code> * (<code>'\u0030'</code>) and <code>'1'</code> * (<code>'\u0031'</code>) are used as binary digits. * * @param i an integer to be converted to a string. * @return the string representation of the unsigned integer value * represented by the argument in binary (base 2). * @since JDK1.0.2 */ public static String toBinaryString(int i) { return toUnsignedString(i, 1); } /** * Convert the integer to an unsigned number. */ private static String toUnsignedString(int i, int shift) { char[] buf = new char[32]; int charPos = 32; int radix = 1 << shift; int mask = radix - 1; do { buf[--charPos] = digits[i & mask]; i >>>= shift; } while (i != 0); return new String(buf, charPos, (32 - charPos)); } final static char [] DigitTens = { '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '1', '1', '1', '1', '1', '1', '1', '1', '1', '1', '2', '2', '2', '2', '2', '2', '2', '2', '2', '2', '3', '3', '3', '3', '3', '3', '3', '3', '3', '3', '4', '4', '4', '4', '4', '4', '4', '4', '4', '4', '5', '5', '5', '5', '5', '5', '5', '5', '5', '5', '6', '6', '6', '6', '6', '6', '6', '6', '6', '6', '7', '7', '7', '7', '7', '7', '7', '7', '7', '7', '8', '8', '8', '8', '8', '8', '8', '8', '8', '8', '9', '9', '9', '9', '9', '9', '9', '9', '9', '9', } ; final static char [] DigitOnes = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', } ; // I use the "invariant division by multiplication" trick to // accelerate Integer.toString. In particular we want to // avoid division by 10. // // The "trick" has roughly the same performance characteristics // as the "classic" Integer.toString code on a non-JIT VM. // The trick avoids .rem and .div calls but has a longer code // path and is thus dominated by dispatch overhead. In the // JIT case the dispatch overhead doesn't exist and the // "trick" is considerably faster than the classic code. // // TODO-FIXME: convert (x * 52429) into the equiv shift-add // sequence. // // RE: Division by Invariant Integers using Multiplication // T Gralund, P Montgomery // ACM PLDI 1994 // /** * Returns a <code>String</code> object representing the * specified integer. The argument is converted to signed decimal * representation and returned as a string, exactly as if the * argument and radix 10 were given as arguments to the [email protected] * #toString(int, int)} method. * * @param i an integer to be converted. * @return a string representation of the argument in base 10. */ public static String toString(int i) { if (i == Integer.MIN_VALUE) return "-2147483648"; int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i); char[] buf = new char[size]; getChars(i, size, buf); return new String(0, size, buf); } /** * Places characters representing the integer i into the * character array buf. The characters are placed into * the buffer backwards starting with the least significant * digit at the specified index (exclusive), and working * backwards from there. * * Will fail if i == Integer.MIN_VALUE */ static void getChars(int i, int index, char[] buf) { int q, r; int charPos = index; char sign = 0; if (i < 0) { sign = '-'; i = -i; } // Generate two digits per iteration while (i >= 65536) { q = i / 100; // really: r = i - (q * 100); r = i - ((q << 6) + (q << 5) + (q << 2)); i = q; buf [--charPos] = DigitOnes[r]; buf [--charPos] = DigitTens[r]; } // Fall thru to fast mode for smaller numbers // assert(i <= 65536, i); for (;;) { q = (i * 52429) >>> (16+3); r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ... buf [--charPos] = digits [r]; i = q; if (i == 0) break; } if (sign != 0) { buf [--charPos] = sign; } } final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999, 99999999, 999999999, Integer.MAX_VALUE }; // Requires positive x static int stringSize(int x) { for (int i=0; ; i++) if (x <= sizeTable[i]) return i+1; } /** * Parses the string argument as a signed integer in the radix * specified by the second argument. The characters in the string * must all be digits of the specified radix (as determined by * whether [email protected] java.lang.Character#digit(char, int)} returns a * nonnegative value), except that the first character may be an * ASCII minus sign <code>'-'</code> (<code>'\u002D'</code>) to * indicate a negative value. The resulting integer value is returned. * <p> * An exception of type <code>NumberFormatException</code> is * thrown if any of the following situations occurs: * <ul> * <li>The first argument is <code>null</code> or is a string of * length zero. * <li>The radix is either smaller than * [email protected] java.lang.Character#MIN_RADIX} or * larger than [email protected] java.lang.Character#MAX_RADIX}. * <li>Any character of the string is not a digit of the specified * radix, except that the first character may be a minus sign * <code>'-'</code> (<code>'\u002D'</code>) provided that the * string is longer than length 1. * <li>The value represented by the string is not a value of type * <code>int</code>. * </ul><p> * Examples: * <blockquote><pre> * parseInt("0", 10) returns 0 * parseInt("473", 10) returns 473 * parseInt("-0", 10) returns 0 * parseInt("-FF", 16) returns -255 * parseInt("1100110", 2) returns 102 * parseInt("2147483647", 10) returns 2147483647 * parseInt("-2147483648", 10) returns -2147483648 * parseInt("2147483648", 10) throws a NumberFormatException * parseInt("99", 8) throws a NumberFormatException * parseInt("Kona", 10) throws a NumberFormatException * parseInt("Kona", 27) returns 411787 * </pre></blockquote> * * @param s the <code>String</code> containing the integer * representation to be parsed * @param radix the radix to be used while parsing <code>s</code>. * @return the integer represented by the string argument in the * specified radix. * @exception NumberFormatException if the <code>String</code> * does not contain a parsable <code>int</code>. */ public static int parseInt(String s, int radix) throws NumberFormatException { if (s == null) { throw new NumberFormatException("null"); } if (radix < Character.MIN_RADIX) { throw new NumberFormatException("radix " + radix + " less than Character.MIN_RADIX"); } if (radix > Character.MAX_RADIX) { throw new NumberFormatException("radix " + radix + " greater than Character.MAX_RADIX"); } int result = 0; boolean negative = false; int i = 0, max = s.length(); int limit; int multmin; int digit; if (max > 0) { if (s.charAt(0) == '-') { negative = true; limit = Integer.MIN_VALUE; i++; } else { limit = -Integer.MAX_VALUE; } multmin = limit / radix; if (i < max) { digit = Character.digit(s.charAt(i++),radix); if (digit < 0) { throw NumberFormatException.forInputString(s); } else { result = -digit; } } while (i < max) { // Accumulating negatively avoids surprises near MAX_VALUE digit = Character.digit(s.charAt(i++),radix); if (digit < 0) { throw NumberFormatException.forInputString(s); } if (result < multmin) { throw NumberFormatException.forInputString(s); } result *= radix; if (result < limit + digit) { throw NumberFormatException.forInputString(s); } result -= digit; } } else { throw NumberFormatException.forInputString(s); } if (negative) { if (i > 1) { return result; } else { /* Only got "-" */ throw NumberFormatException.forInputString(s); } } else { return -result; } } /** * Parses the string argument as a signed decimal integer. The * characters in the string must all be decimal digits, except that * the first character may be an ASCII minus sign <code>'-'</code> * (<code>'\u002D'</code>) to indicate a negative value. The resulting * integer value is returned, exactly as if the argument and the radix * 10 were given as arguments to the * [email protected] #parseInt(java.lang.String, int)} method. * * @param s a <code>String</code> containing the <code>int</code> * representation to be parsed * @return the integer value represented by the argument in decimal. * @exception NumberFormatException if the string does not contain a * parsable integer. */ public static int parseInt(String s) throws NumberFormatException { return parseInt(s,10); } /** * Returns an <code>Integer</code> object holding the value * extracted from the specified <code>String</code> when parsed * with the radix given by the second argument. The first argument * is interpreted as representing a signed integer in the radix * specified by the second argument, exactly as if the arguments * were given to the [email protected] #parseInt(java.lang.String, int)} * method. The result is an <code>Integer</code> object that * represents the integer value specified by the string. * <p> * In other words, this method returns an <code>Integer</code> * object equal to the value of: * * <blockquote><code> * new Integer(Integer.parseInt(s, radix)) * </code></blockquote> * * @param s the string to be parsed. * @param radix the radix to be used in interpreting <code>s</code> * @return an <code>Integer</code> object holding the value * represented by the string argument in the specified * radix. * @exception NumberFormatException if the <code>String</code> * does not contain a parsable <code>int</code>. */ public static Integer valueOf(String s, int radix) throws NumberFormatException { return Integer.valueOf(parseInt(s,radix)); } /** * Returns an <code>Integer</code> object holding the * value of the specified <code>String</code>. The argument is * interpreted as representing a signed decimal integer, exactly * as if the argument were given to the [email protected] * #parseInt(java.lang.String)} method. The result is an * <code>Integer</code> object that represents the integer value * specified by the string. * <p> * In other words, this method returns an <code>Integer</code> * object equal to the value of: * * <blockquote><code> * new Integer(Integer.parseInt(s)) * </code></blockquote> * * @param s the string to be parsed. * @return an <code>Integer</code> object holding the value * represented by the string argument. * @exception NumberFormatException if the string cannot be parsed * as an integer. */ public static Integer valueOf(String s) throws NumberFormatException { return Integer.valueOf(parseInt(s, 10)); } /** * Cache to support the object identity semantics of autoboxing for values between * -128 and 127 (inclusive) as required by JLS. * * The cache is initialized on first usage. During VM initialization the * getAndRemoveCacheProperties method may be used to get and remove any system * properites that configure the cache size. At this time, the size of the * cache may be controlled by the vm option -XX:AutoBoxCacheMax=<size>. */ // value of java.lang.Integer.IntegerCache.high property (obtained during VM init) private static String integerCacheHighPropValue; static void getAndRemoveCacheProperties() { if (!sun.misc.VM.isBooted()) { Properties props = System.getProperties(); integerCacheHighPropValue = (String)props.remove("java.lang.Integer.IntegerCache.high"); if (integerCacheHighPropValue != null) System.setProperties(props); // remove from system props } } private static class IntegerCache { static final int high; static final Integer cache[]; static { final int low = -128; // high value may be configured by property int h = 127; if (integerCacheHighPropValue != null) { // Use Long.decode here to avoid invoking methods that // require Integer's autoboxing cache to be initialized int i = Long.decode(integerCacheHighPropValue).intValue(); i = Math.max(i, 127); // Maximum array size is Integer.MAX_VALUE h = Math.min(i, Integer.MAX_VALUE - -low); } high = h; cache = new Integer[(high - low) + 1]; int j = low; for(int k = 0; k < cache.length; k++) cache[k] = new Integer(j++); } private IntegerCache() {} } /** * Returns a <tt>Integer</tt> instance representing the specified * <tt>int</tt> value. * If a new <tt>Integer</tt> instance is not required, this method * should generally be used in preference to the constructor * [email protected] #Integer(int)}, as this method is likely to yield * significantly better space and time performance by caching * frequently requested values. * * @param i an <code>int</code> value. * @return a <tt>Integer</tt> instance representing <tt>i</tt>. * @since 1.5 */ public static Integer valueOf(int i) { if(i >= -128 && i <= IntegerCache.high) return IntegerCache.cache[i + 128]; else return new Integer(i); } /** * The value of the <code>Integer</code>. * * @serial */ private final int value; /** * Constructs a newly allocated <code>Integer</code> object that * represents the specified <code>int</code> value. * * @param value the value to be represented by the * <code>Integer</code> object. */ public Integer(int value) { this.value = value; } /** * Constructs a newly allocated <code>Integer</code> object that * represents the <code>int</code> value indicated by the * <code>String</code> parameter. The string is converted to an * <code>int</code> value in exactly the manner used by the * <code>parseInt</code> method for radix 10. * * @param s the <code>String</code> to be converted to an * <code>Integer</code>. * @exception NumberFormatException if the <code>String</code> does not * contain a parsable integer. * @see java.lang.Integer#parseInt(java.lang.String, int) */ public Integer(String s) throws NumberFormatException { this.value = parseInt(s, 10); } /** * Returns the value of this <code>Integer</code> as a * <code>byte</code>. */ public byte byteValue() { return (byte)value; } /** * Returns the value of this <code>Integer</code> as a * <code>short</code>. */ public short shortValue() { return (short)value; } /** * Returns the value of this <code>Integer</code> as an * <code>int</code>. */ public int intValue() { return value; } /** * Returns the value of this <code>Integer</code> as a * <code>long</code>. */ public long longValue() { return (long)value; } /** * Returns the value of this <code>Integer</code> as a * <code>float</code>. */ public float floatValue() { return (float)value; } /** * Returns the value of this <code>Integer</code> as a * <code>double</code>. */ public double doubleValue() { return (double)value; } /** * Returns a <code>String</code> object representing this * <code>Integer</code>'s value. The value is converted to signed * decimal representation and returned as a string, exactly as if * the integer value were given as an argument to the [email protected] * java.lang.Integer#toString(int)} method. * * @return a string representation of the value of this object in * base 10. */ public String toString() { return String.valueOf(value); } /** * Returns a hash code for this <code>Integer</code>. * * @return a hash code value for this object, equal to the * primitive <code>int</code> value represented by this * <code>Integer</code> object. */ public int hashCode() { return value; } /** * Compares this object to the specified object. The result is * <code>true</code> if and only if the argument is not * <code>null</code> and is an <code>Integer</code> object that * contains the same <code>int</code> value as this object. * * @param obj the object to compare with. * @return <code>true</code> if the objects are the same; * <code>false</code> otherwise. */ public boolean equals(Object obj) { if (obj instanceof Integer) { return value == ((Integer)obj).intValue(); } return false; } /** * Determines the integer value of the system property with the * specified name. * <p> * The first argument is treated as the name of a system property. * System properties are accessible through the * [email protected] java.lang.System#getProperty(java.lang.String)} method. The * string value of this property is then interpreted as an integer * value and an <code>Integer</code> object representing this value is * returned. Details of possible numeric formats can be found with * the definition of <code>getProperty</code>. * <p> * If there is no property with the specified name, if the specified name * is empty or <code>null</code>, or if the property does not have * the correct numeric format, then <code>null</code> is returned. * <p> * In other words, this method returns an <code>Integer</code> * object equal to the value of: * * <blockquote><code> * getInteger(nm, null) * </code></blockquote> * * @param nm property name. * @return the <code>Integer</code> value of the property. * @see java.lang.System#getProperty(java.lang.String) * @see java.lang.System#getProperty(java.lang.String, java.lang.String) */ public static Integer getInteger(String nm) { return getInteger(nm, null); } /** * Determines the integer value of the system property with the * specified name. * <p> * The first argument is treated as the name of a system property. * System properties are accessible through the [email protected] * java.lang.System#getProperty(java.lang.String)} method. The * string value of this property is then interpreted as an integer * value and an <code>Integer</code> object representing this value is * returned. Details of possible numeric formats can be found with * the definition of <code>getProperty</code>. * <p> * The second argument is the default value. An <code>Integer</code> object * that represents the value of the second argument is returned if there * is no property of the specified name, if the property does not have * the correct numeric format, or if the specified name is empty or * <code>null</code>. * <p> * In other words, this method returns an <code>Integer</code> object * equal to the value of: * <blockquote><code> * getInteger(nm, new Integer(val)) * </code></blockquote> * but in practice it may be implemented in a manner such as: * <blockquote><pre> * Integer result = getInteger(nm, null); * return (result == null) ? new Integer(val) : result; * </pre></blockquote> * to avoid the unnecessary allocation of an <code>Integer</code> * object when the default value is not needed. * * @param nm property name. * @param val default value. * @return the <code>Integer</code> value of the property. * @see java.lang.System#getProperty(java.lang.String) * @see java.lang.System#getProperty(java.lang.String, java.lang.String) */ public static Integer getInteger(String nm, int val) { Integer result = getInteger(nm, null); return (result == null) ? Integer.valueOf(val) : result; } /** * Returns the integer value of the system property with the * specified name. The first argument is treated as the name of a * system property. System properties are accessible through the * [email protected] java.lang.System#getProperty(java.lang.String)} method. * The string value of this property is then interpreted as an * integer value, as per the <code>Integer.decode</code> method, * and an <code>Integer</code> object representing this value is * returned. * <p> * <ul><li>If the property value begins with the two ASCII characters * <code>0x</code> or the ASCII character <code>#</code>, not * followed by a minus sign, then the rest of it is parsed as a * hexadecimal integer exactly as by the method * [email protected] #valueOf(java.lang.String, int)} with radix 16. * <li>If the property value begins with the ASCII character * <code>0</code> followed by another character, it is parsed as an * octal integer exactly as by the method * [email protected] #valueOf(java.lang.String, int)} with radix 8. * <li>Otherwise, the property value is parsed as a decimal integer * exactly as by the method [email protected] #valueOf(java.lang.String, int)} * with radix 10. * </ul><p> * The second argument is the default value. The default value is * returned if there is no property of the specified name, if the * property does not have the correct numeric format, or if the * specified name is empty or <code>null</code>. * * @param nm property name. * @param val default value. * @return the <code>Integer</code> value of the property. * @see java.lang.System#getProperty(java.lang.String) * @see java.lang.System#getProperty(java.lang.String, java.lang.String) * @see java.lang.Integer#decode */ public static Integer getInteger(String nm, Integer val) { String v = null; try { v = System.getProperty(nm); } catch (IllegalArgumentException e) { } catch (NullPointerException e) { } if (v != null) { try { return Integer.decode(v); } catch (NumberFormatException e) { } } return val; } /** * Decodes a <code>String</code> into an <code>Integer</code>. * Accepts decimal, hexadecimal, and octal numbers given * by the following grammar: * * <blockquote> * <dl> * <dt><i>DecodableString:</i> * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> * <dd><i>Sign<sub>opt</sub></i> <code>0x</code> <i>HexDigits</i> * <dd><i>Sign<sub>opt</sub></i> <code>0X</code> <i>HexDigits</i> * <dd><i>Sign<sub>opt</sub></i> <code>#</code> <i>HexDigits</i> * <dd><i>Sign<sub>opt</sub></i> <code>0</code> <i>OctalDigits</i> * <p> * <dt><i>Sign:</i> * <dd><code>-</code> * </dl> * </blockquote> * * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> * are defined in <a href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#48282">§3.10.1</a> * of the <a href="http://java.sun.com/docs/books/jls/html/">Java * Language Specification</a>. * <p> * The sequence of characters following an (optional) negative * sign and/or radix specifier ("<code>0x</code>", * "<code>0X</code>", "<code>#</code>", or * leading zero) is parsed as by the <code>Integer.parseInt</code> * method with the indicated radix (10, 16, or 8). This sequence * of characters must represent a positive value or a [email protected] * NumberFormatException} will be thrown. The result is negated * if first character of the specified <code>String</code> is the * minus sign. No whitespace characters are permitted in the * <code>String</code>. * * @param nm the <code>String</code> to decode. * @return a <code>Integer</code> object holding the <code>int</code> * value represented by <code>nm</code> * @exception NumberFormatException if the <code>String</code> does not * contain a parsable integer. * @see java.lang.Integer#parseInt(java.lang.String, int) */ public static Integer decode(String nm) throws NumberFormatException { int radix = 10; int index = 0; boolean negative = false; Integer result; // Handle minus sign, if present if (nm.startsWith("-")) { negative = true; index++; } // Handle radix specifier, if present if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) { index += 2; radix = 16; } else if (nm.startsWith("#", index)) { index ++; radix = 16; } else if (nm.startsWith("0", index) && nm.length() > 1 + index) { index ++; radix = 8; } if (nm.startsWith("-", index)) throw new NumberFormatException("Negative sign in wrong position"); try { result = Integer.valueOf(nm.substring(index), radix); result = negative ? Integer.valueOf(-result.intValue()) : result; } catch (NumberFormatException e) { // If number is Integer.MIN_VALUE, we'll end up here. The next line // handles this case, and causes any genuine format error to be // rethrown. String constant = negative ? "-" + nm.substring(index) : nm.substring(index); result = Integer.valueOf(constant, radix); } return result; } /** * Compares two <code>Integer</code> objects numerically. * * @param anotherInteger the <code>Integer</code> to be compared. * @return the value <code>0</code> if this <code>Integer</code> is * equal to the argument <code>Integer</code>; a value less than * <code>0</code> if this <code>Integer</code> is numerically less * than the argument <code>Integer</code>; and a value greater * than <code>0</code> if this <code>Integer</code> is numerically * greater than the argument <code>Integer</code> (signed * comparison). * @since 1.2 */ public int compareTo(Integer anotherInteger) { int thisVal = this.value; int anotherVal = anotherInteger.value; return (thisVal<anotherVal ? -1 : (thisVal==anotherVal ? 0 : 1)); } // Bit twiddling /** * The number of bits used to represent an <tt>int</tt> value in two's * complement binary form. * * @since 1.5 */ public static final int SIZE = 32; /** * Returns an <tt>int</tt> value with at most a single one-bit, in the * position of the highest-order ("leftmost") one-bit in the specified * <tt>int</tt> value. Returns zero if the specified value has no * one-bits in its two's complement binary representation, that is, if it * is equal to zero. * * @return an <tt>int</tt> value with a single one-bit, in the position * of the highest-order one-bit in the specified value, or zero if * the specified value is itself equal to zero. * @since 1.5 */ public static int highestOneBit(int i) { // HD, Figure 3-1 i |= (i >> 1); i |= (i >> 2); i |= (i >> 4); i |= (i >> 8); i |= (i >> 16); return i - (i >>> 1); } /** * Returns an <tt>int</tt> value with at most a single one-bit, in the * position of the lowest-order ("rightmost") one-bit in the specified * <tt>int</tt> value. Returns zero if the specified value has no * one-bits in its two's complement binary representation, that is, if it * is equal to zero. * * @return an <tt>int</tt> value with a single one-bit, in the position * of the lowest-order one-bit in the specified value, or zero if * the specified value is itself equal to zero. * @since 1.5 */ public static int lowestOneBit(int i) { // HD, Section 2-1 return i & -i; } /** * Returns the number of zero bits preceding the highest-order * ("leftmost") one-bit in the two's complement binary representation * of the specified <tt>int</tt> value. Returns 32 if the * specified value has no one-bits in its two's complement representation, * in other words if it is equal to zero. * * <p>Note that this method is closely related to the logarithm base 2. * For all positive <tt>int</tt> values x: * <ul> * <li>floor(log<sub>2</sub>(x)) = <tt>31 - numberOfLeadingZeros(x)</tt> * <li>ceil(log<sub>2</sub>(x)) = <tt>32 - numberOfLeadingZeros(x - 1)</tt> * </ul> * * @return the number of zero bits preceding the highest-order * ("leftmost") one-bit in the two's complement binary representation * of the specified <tt>int</tt> value, or 32 if the value * is equal to zero. * @since 1.5 */ public static int numberOfLeadingZeros(int i) { // HD, Figure 5-6 if (i == 0) return 32; int n = 1; if (i >>> 16 == 0) { n += 16; i <<= 16; } if (i >>> 24 == 0) { n += 8; i <<= 8; } if (i >>> 28 == 0) { n += 4; i <<= 4; } if (i >>> 30 == 0) { n += 2; i <<= 2; } n -= i >>> 31; return n; } /** * Returns the number of zero bits following the lowest-order ("rightmost") * one-bit in the two's complement binary representation of the specified * <tt>int</tt> value. Returns 32 if the specified value has no * one-bits in its two's complement representation, in other words if it is * equal to zero. * * @return the number of zero bits following the lowest-order ("rightmost") * one-bit in the two's complement binary representation of the * specified <tt>int</tt> value, or 32 if the value is equal * to zero. * @since 1.5 */ public static int numberOfTrailingZeros(int i) { // HD, Figure 5-14 int y; if (i == 0) return 32; int n = 31; y = i <<16; if (y != 0) { n = n -16; i = y; } y = i << 8; if (y != 0) { n = n - 8; i = y; } y = i << 4; if (y != 0) { n = n - 4; i = y; } y = i << 2; if (y != 0) { n = n - 2; i = y; } return n - ((i << 1) >>> 31); } /** * Returns the number of one-bits in the two's complement binary * representation of the specified <tt>int</tt> value. This function is * sometimes referred to as the <i>population count</i>. * * @return the number of one-bits in the two's complement binary * representation of the specified <tt>int</tt> value. * @since 1.5 */ public static int bitCount(int i) { // HD, Figure 5-2 i = i - ((i >>> 1) & 0x55555555); i = (i & 0x33333333) + ((i >>> 2) & 0x33333333); i = (i + (i >>> 4)) & 0x0f0f0f0f; i = i + (i >>> 8); i = i + (i >>> 16); return i & 0x3f; } /** * Returns the value obtained by rotating the two's complement binary * representation of the specified <tt>int</tt> value left by the * specified number of bits. (Bits shifted out of the left hand, or * high-order, side reenter on the right, or low-order.) * * <p>Note that left rotation with a negative distance is equivalent to * right rotation: <tt>rotateLeft(val, -distance) == rotateRight(val, * distance)</tt>. Note also that rotation by any multiple of 32 is a * no-op, so all but the last five bits of the rotation distance can be * ignored, even if the distance is negative: <tt>rotateLeft(val, * distance) == rotateLeft(val, distance & 0x1F)</tt>. * * @return the value obtained by rotating the two's complement binary * representation of the specified <tt>int</tt> value left by the * specified number of bits. * @since 1.5 */ public static int rotateLeft(int i, int distance) { return (i << distance) | (i >>> -distance); } /** * Returns the value obtained by rotating the two's complement binary * representation of the specified <tt>int</tt> value right by the * specified number of bits. (Bits shifted out of the right hand, or * low-order, side reenter on the left, or high-order.) * * <p>Note that right rotation with a negative distance is equivalent to * left rotation: <tt>rotateRight(val, -distance) == rotateLeft(val, * distance)</tt>. Note also that rotation by any multiple of 32 is a * no-op, so all but the last five bits of the rotation distance can be * ignored, even if the distance is negative: <tt>rotateRight(val, * distance) == rotateRight(val, distance & 0x1F)</tt>. * * @return the value obtained by rotating the two's complement binary * representation of the specified <tt>int</tt> value right by the * specified number of bits. * @since 1.5 */ public static int rotateRight(int i, int distance) { return (i >>> distance) | (i << -distance); } /** * Returns the value obtained by reversing the order of the bits in the * two's complement binary representation of the specified <tt>int</tt> * value. * * @return the value obtained by reversing order of the bits in the * specified <tt>int</tt> value. * @since 1.5 */ public static int reverse(int i) { // HD, Figure 7-1 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555; i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333; i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f; i = (i << 24) | ((i & 0xff00) << 8) | ((i >>> 8) & 0xff00) | (i >>> 24); return i; } /** * Returns the signum function of the specified <tt>int</tt> value. (The * return value is -1 if the specified value is negative; 0 if the * specified value is zero; and 1 if the specified value is positive.) * * @return the signum function of the specified <tt>int</tt> value. * @since 1.5 */ public static int signum(int i) { // HD, Section 2-7 return (i >> 31) | (-i >>> 31); } /** * Returns the value obtained by reversing the order of the bytes in the * two's complement representation of the specified <tt>int</tt> value. * * @return the value obtained by reversing the bytes in the specified * <tt>int</tt> value. * @since 1.5 */ public static int reverseBytes(int i) { return ((i >>> 24) ) | ((i >> 8) & 0xFF00) | ((i << 8) & 0xFF0000) | ((i << 24)); } /** use serialVersionUID from JDK 1.0.2 for interoperability */ private static final long serialVersionUID = 1360826667806852920L;}
注意到其类成员和构造函数：
/** * The value of the <code>Integer</code>. * * @serial */ private final int value; /** * Constructs a newly allocated <code>Integer</code> object that * represents the specified <code>int</code> value. * * @param value the value to be represented by the * <code>Integer</code> object. */ public Integer(int value) { this.value = value; }什么？前面有final关键字，也就是说，Integer箱子里面的Value(int)是不能被改变的，那这个类的作用在于什么呢？我想是：①java提倡将万物看为对象，必不可少的基本类型反而破坏了其提倡的封装性。于是，干脆弄几个wrapper将基本类型包装起来，也相应的提供了一些操作类！
②使用起来比int等基本类型更为安全，你如一个int i;你只声明了i但没有赋值，会自动在下文i=0;但是如果你用了Integer i;而没有调用构造的话就是i=null;在下文直接使用i就会报错，在一定程度上增大了代码的安全性。
言归正传，那我们一开始的问题怎么解决呢？我不想自己再写一个包装类，于是就使用了数组！数组里的值总得是引用传递吧！（话说AsyncTask的三个参数也是泛型数，估计我们之间的思想是不谋而合的）
public class AskFragment extends Fragment implements OnClickListener { private static Boolean[] isFirstEnter={true}; private Integer[] min_question_id={1000}; public void onActivityCreated(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onActivityCreated(savedInstanceState);new getQuestionListDataTask(mPullToRefreshLayout, listItemQuestion, isFirstEnter, min_question_id, mQuestionListAdapter).execute(); }}public class getQuestionListDataTask extends AsyncTask<Void, Void, Void>{ private static final int GETREFRESUCCESS=5000; private static final int GETREQUESTERROR=5001; private static final int DATASETEMPTY=5002; PullToRefreshListView mPullToRefreshLayout; List<HashMap<String, Object>> listItemQuestion; Boolean[] isFirstEnter; Integer[] min_question_id; QuestionListAdapter mQuestionListAdapter; /* * mpPullToRefreshListView:异步刷新工作对应的PullToRefreshListView * mList:PullToRefreshListView对应的后台数据引用 * isfirstEnter:记录是否第一次开机后第一次进入app * min_question_id:获取问题列表时候的最小id * mQuestionListAdapter:驱动mpPullToRefreshListView的适配器 */ public getQuestionListDataTask(PullToRefreshListView mPullToRefreshListView,List<HashMap<String, Object>> mList, Boolean[] isfirstEnter,Integer[] min_question_id,QuestionListAdapter mQuestionListAdapter) { super(); this.mPullToRefreshLayout=mPullToRefreshListView; this.listItemQuestion=mList; this.isFirstEnter=isfirstEnter; this.min_question_id=min_question_id; this.mQuestionListAdapter=mQuestionListAdapter; } @Override protected Void doInBackground(Void... arg0) { // TODO Auto-generated method stub if(mPullToRefreshLayout.isHeaderShown()) { listItemQuestion.clear(); getQuestionListData(new Integer[]{0}, true); isFirstEnter[0]=false; } if(mPullToRefreshLayout.isFooterShown()) { getQuestionListData(min_question_id,false); } else { listItemQuestion.clear(); getQuestionListData(new Integer[]{0}, true); //getHttpData(min_question_id,false); } return null; } @Override protected void onPostExecute(Void result) { // TODO Auto-generated method stub mQuestionListAdapter.notifyDataSetChanged(); mPullToRefreshLayout.onRefreshComplete(); super.onPostExecute(result); }}就这样，就真的搞定了问题！说明：由于只是示例作用，代码截自我的项目，很多东西删去了，也有的变量没初始化，但大家不要介意这些细节~