Java方法参数传递机制原理解析

public class TransferTempTest {
  public static void main(String[] args) {
    //基本数据类型参数传递
    TransferTempTest test = new TransferTempTest();
    int num1 = 10;
    int num2 = 20;
    System.out.println("进行交换前：");
    System.out.println("num1 = " + num1 + ",num2 = " + num2);
    test.swap(num1, num2);
    System.out.println("交换之后：");
    System.out.println("num1 = " + num1 + ",num2 = " + num2);
  }
  public void swap(int a, int b) {
    int temp = a;
    a = b;
    b = temp;
    System.out.println("交换过程中：");
    System.out.println("num1 = " + a + ",num2 = " + b);
  }
}

//运行结果
进行交换前：
num1 = 10,num2 = 20
交换过程中：
num1 = 20,num2 = 10
交换之后：
num1 = 10,num2 = 20

public class TransferTempTest {
  public static void main(String[] args) {
  //引用类型参数传递
    DataTemp data = new DataTemp();
    data.a = 2;
    data.b = 4;
    System.out.println("进行交换前：");
    System.out.println("data.a = " + data.a + ",data.b = " + data.b);
    data.swapClass(data);
    System.out.println("进行交换后：");
    System.out.println("data.a = " + data.a + ",data.b = " + data.b);
  }
}
class DataTemp {
  int a;
  int b;

  public void swapClass(DataTemp data) {
    int temp = data.a;
    data.a = data.b;
    data.b = temp;
    System.out.println("交换过程中：");
    System.out.println("data.a = " + data.a + ",data.b = " + data.b);

  }
}

//运行结果
进行交换前：
data.a = 2,data.b = 4
交换过程中：
data.a = 4,data.b = 2
进行交换后：
data.a = 4,data.b = 2

package com.my.pac05;

public class TransferTest {
  public static void main(String[] args) {
    TransferTest test = new TransferTest();
    test.first();
  }

  public void first() {
    int i = 5;
    Value v = new Value();

    v.i = 25;
    second(v, i);
    System.out.println(v.i);
  }

  public void second(Value v, int i) {
    i = 0;
    v.i = 20;
    Value val = new Value();
    v = val;
    System.out.println(v.i + " " + i);
  }
}

class Value {
  int i = 15;
}

//运行结果
15 0
20