try-catch-finally执行顺序及语句中对变量进行赋值的问题

本文详细探讨了Java中try-catch-finally语句块的执行顺序。当finally块存在时，无论是否包含return，都会先执行finally块。如果finally无return，会继续执行try或catch中的return。如果有return，则直接返回finally中的值。对于返回值，如果是基本类型，在finally中改变不会影响返回；如果是引用类型，虽然引用可以改变，但对象属性的修改会影响返回值。

package com.zte.lzz.leetcode.tryCatchFinally;

/**
 * try-catch-finally 执行顺序及finally修改属性值问题总结
 */
public class TryCatchFinallyDemo {
    public static void main(String[] args) {
        System.out.println(show01());
        System.out.println("-----------------------------------");
        System.out.println(show02());
        System.out.println("-----------------------------------");
        System.out.println(show03());
        System.out.println("-----------------------------------");
        System.out.println(show04());
        System.out.println("-----------------------------------");
        System.out.println(show05());
        System.out.println("-----------------------------------");
        TryCatchFinallyDemo demo = new TryCatchFinallyDemo();
        System.out.println(demo.m1().toString());
        System.out.println("-----------------------------------");
        System.out.println("-----------------------------------");
        System.out.println(demo.m2().toString());
        System.out.println("-----------------------------------");
        System.out.println(demo.m3().toString());

    }
    public static int show01() {
        try {
            return 1;
        }finally{
            System.out.println("finally模块被执行,01");
        }
    }
    public static int show02() {
        try {
            int a = 8/0;
            return 1;
        }catch (Exception e) {
            return 2;
        }finally{
            System.out.println("finally模块被执行,02");
        }
    }
    public static int show03() {
        try {
            int a = 8/0;
            return 1;
        }catch (Exception e) {
            return 2;
        }finally{
            System.out.println("finally模块被执行,03");
            return 0;
        }
    }
    public static int show04() {
        int result = 0;
        try {
            return result;
        }finally{
            System.out.println("finally模块被执行,04");
            result = 1;
        }
    }
    public static Object show05() {
        Object obj = new Object();
        try {
            return obj;
        }finally{
            System.out.println("finally模块被执行,05");
            obj = null;
        }
    }
    public LOl m1(){
        LOl lOl = new LOl();
        try {
            return lOl;
        }finally {
            System.out.println("finally模块被执行,m1");
            lOl = null;
        }
    }
    public LOl m2(){
        LOl lOl = new LOl();
        try {
            lOl.setAge(20);
            lOl.setName("jack");
            return lOl;
        }finally {
            System.out.println("finally模块被执行,m2");
            lOl.setAge(25);
            lOl.setName("rose");
        }
    }
    public LOl m3(){
        LOl lOl = new LOl();
        try {
            lOl.setAge(20);
            lOl.setName("jack");
            return lOl;
        }finally {
            System.out.println("finally模块被执行,m3");
            lOl.setAge(25);
            lOl.setName("rose");
            return lOl;
        }
    }
    class LOl{
        private String name;
        private int age;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        @Override
        public String toString() {
            return "LOl{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }
    }
}

finally模块被执行,01
1
-----------------------------------
finally模块被执行,02
2
-----------------------------------
finally模块被执行,03
0
-----------------------------------
finally模块被执行,04
0
-----------------------------------
finally模块被执行,05
java.lang.Object@18769467
-----------------------------------
finally模块被执行,m1
LOl{name='null', age=0}
-----------------------------------
-----------------------------------
finally模块被执行,m2
LOl{name='rose', age=25}
-----------------------------------
finally模块被执行,m3
LOl{name='rose', age=25}

Process finished with exit code 0

结果及结论：

执行顺序：

1，finally无return，执行完finally代码，再执行try或者catch里面return

2，finally有return，执行finally里面return，不再执行try或者catch里面return

finally修改值问题：

3，如果在执行finally块前出现return语句，会把在值先缓存起来，等执行完finally块后，再返回缓存起来的值。

4，如果是返回基本类型的值，那么在缓存时也是缓存值本身，所以后面在finally块中重新赋值时，方法返回的值不会受finally块中重新赋值的影响；

如果返回的是引用类型的值，那么在缓存时，缓存的是引用类型对象的引用，所以虽然后面在finally块中重新赋值时（重新指向另一个对象），方法返回的值不会受到影响，但是如果是修改对象的属性，那么会影响到返回的值。