0x07-我在写 java swap 函数时理解了值传递与引用

public void swap(int a, int b) {
      int temp = a;
      a = b;
      b = temp;
}

public static int swap(int itself, int dummy)
{
    return itself;
}

public static void main(String[] args)
{
    int a = 10;
    int b = 20;

    a = swap(b, b = a);
}

class MyInteger {
   private int x;                   // single data member
   public MyInteger(int xIn) { x = xIn; } // constructor
   public int getValue() { return x; }  // retrieve value
   public void insertValue(int xIn) { x = xIn;} // insert
}

public class Swapping {
   // swap: pass references to objects
   static void swap(MyInteger rWrap, MyInteger sWrap) {
      // interchange values inside objects
      int t = rWrap.getValue();
      rWrap.insertValue(sWrap.getValue());
      sWrap.insertValue(t);
   }

   public static void main(String[] args) {
      int a = 23, b = 47;
      System.out.println("Before. a:" + a + ", b: " + b);
      MyInteger aWrap = new MyInteger(a);
      MyInteger bWrap = new MyInteger(b);
      swap(aWrap, bWrap);
      a = aWrap.getValue();
      b = bWrap.getValue();
      System.out.println("After.  a:" + a + ", b: " + b);
   }
}