java如何交换两个整数包装器对象

Question

如何交换两个整数包装的内容

void swap(Integer a,Integer b){
   /*We can't use this as it will not reflect in calling program,and i know why
    Integer c = a;
    a= b;
    b = c;
   */
  //how can i swap them ? Does Integer has some setValue kind of method?
  //if yes
    int c = a;
    a.setValue(b);
    b.setValue(c);

}

Answer 1

public class NewInteger {
    private int a;
    private int b;

    public int getA() {
        return a;
    }

    public int getB() {
        return b;
    }

    public NewInteger(int a, int b) {
        this.a = a;
        this.b = b;
    }

    public void swap(){
        int c = this.a;
        this.a = this.b;
        this.b = c;
    }
}


NewInteger obj = new NewInteger(1, 2);
System.out.println(obj.getA());
System.out.println(obj.getB());
obj.swap();
System.out.println(obj.getA());
System.out.println(obj.getB());

输出： 1. 2. 2. 一,

Answer 2

类型java.lang.Integer表示一个永远不会改变其值的不可变的数。如果您想要一个可变的数字，请从Apache Commons中尝试MutableInt

与C++相比，不能将引用传递给任意的内存位置，所以在大多数情况下交换是不可能的。你能得到的最接近的东西是：

public static void swap(Integer[] ints, int index1, int index2) {
  Integer tmp = ints[index1];
  ints[index1] = ints[index2];
  ints[index2] = tmp;
}

您可以使用List<T>编写类似的代码，但您总是需要一个（或两个）容器来交换东西