最近在自学java,看得是张孝祥的书。
恳求大哥大姐们帮忙啊，困扰好久了！
以下是程序，
class HashtableTest是测试Hashtable类的，通过自己编写的类对Hashtable的关键字和值分别返回。
class MyKeyTest是测试equals()方法的，自己编写的覆盖Object中的equals
// Date: 2007/1/4
// From page 229 and 141-142;
import java.util.*;
class MyKey
{
private String name;
private int age;
public MyKey(String name, int age)
{
this.name = name;
this.age = age;
}
public String toString()
{
return new String( name + ", " + age);
}
public boolean equals(Object obj)/////////88
{
// MyKey newObj = (MyKey)obj;
// if(name == newObj.name && age==newObj.age);
//public boolean equals(MyKey obj)
//if(name.equals(obj.name) && age==obj.age)
if(name.equals(((MyKey)obj).name) && age==((MyKey)obj).age)///99
return true; // name.equals()调用的是谁的equals()??
else
return false;
}
public int hashcode()
{
return (name.hashCode() + age);
}
}
class HashtableTest
{
public void test()
{
Hashtable numbers = new Hashtable();
numbers.put(new MyKey( "ZhangSan ",18),new Integer (1));
numbers.put(new MyKey( "LiSi ",19),new Integer (2));
numbers.put(new MyKey( "WangWu ",20),new Integer (3));
Enumeration e = numbers.keys();
while(e.hasMoreElements())
{
MyKey key = (MyKey)e.nextElement();
System.out.print(key.toString() + " = ");
System.out.println(numbers.get(key));
4444 // get(key)输出的顺序不是put()时候的顺序，并且输出顺序还不固定？？
System.out.println(key.hashcode());
}
// 得到关键字Key
Enumeration f = numbers.elements();
while(f.hasMoreElements())
{
Integer ele = (Integer)f.nextElement();
System.out.println(ele.intValue());
} }
// 得到值Value
}
}
class MyKeyTest
{
MyKey p = new MyKey( "LaoLi ",30);
MyKey q = new MyKey( "LaoLi ",30);
public void test()
{
if(p.equals(q))
System.out.println( "p = q ");
else
System.out.println( "p != q ");
}
}
public class HashTable_Equals_Test
{
public static void main(String[] args)
{
HashtableTest hashTest = new HashtableTest();