Java＆＃39; + =＆＃39;复合运算符工作概念

Question

我只是想知道它们之间有什么区别 a = a+b;和a += b;

考虑，

int a = 10;
long b = 20;

a = a+b; // is not possible 

但

a += b; // is possible.

谢谢！

package com.test;


public class ClassCast {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        int a = 1;
        long b = 2;

        /*Not possible. Compile time error.
        a = a+b;
        */

        //Possible. Why?
        //a += b;

        System.out.println(a += b);

    }

}

Answer 1

所以a + = b相当于a =（int）（a + b）。

由编译器完成的隐式转换