如下面代码测试，程序输出
a: 39.199999999999996
b: 8.93
怎么能让a的值是39.20?
public class TestDouble {
public void testDouble(){
double a = 43.12 - 3.92;
double b = 12.01 - 3.08;
System.out.println( "a: " + a);
System.out.println( "b: " + b);
}
public static void main(String[] args){
TestDouble d = new TestDouble();
d.testDouble();
}
}
谢谢！
------解决方案--------------------
给你一个提示，四舍五入
------解决方案--------------------
public class test {
public void testDouble(){
double a = 43.12 - 3.92;
double b = 12.01 - 3.08;
java.text.DecimalFormat df = new DecimalFormat( "#.00 ");
System.out.println( "a: " + df.format(a));
System.out.println( "b: " + df.format(b));
}
public static void main(String[] args){
test d = new test();
d.testDouble();
}
------解决方案--------------------
很简单啊，用java.text包就可以了
import java.text.DecimalFormat;
public class TestDouble {
public void testDouble(){
double a = 43.12 - 3.92;
double b = 12.01 - 3.08;
System.out.println( "a: " + TestDouble.formatDecimal(a, "#.00 "));
System.out.println( "b: " + b);
}
public static void main(String[] args){
TestDouble d = new TestDouble();
d.testDouble();
}
/**
* 根据格式得到格式化的浮点型数字
* @param data 要格式化的数字，类型为double
* @param type 格式类型，如#,###.00
* @return String 返回String类型的数值，形式如：23,345,445.34
*/
public static String formatDecimal(double data, String type) {
DecimalFormat dFormat = new DecimalFormat(type);
return dFormat.format(data);
}
}