finally

不要在 finally 语句块中使用 return! 当 try 语句和 finally 语句中都有 return 语句时，try 语句块中的 return 语句会被忽略。这是因为 try 语句中的 return 返回值会先被暂存在一个本地变量中，当执行到 finally 语句中的 return 之后，这个本地变量的值就变为了 finally 语句中的 return 返回值。

public class FinallyTest {
    public static void main(String[] args) {
        System.out.println("返回基本类型的try，返回值为："+basicMethod());//1
        System.out.println("返回基本类型的try finallyReturn()，返回值为："+basicMethod_finallyReturn());//3

        System.out.println("返回对象类型的try，"+objectMethod());//3
        System.out.println("返回对象类型的try finallyReturn()，"+objectMethod_finallyReturn());//3

        System.out.println("返回对象类型的try catchReturn()，"+objectMethod_catchReturn());//3

    }

    //返回基本类型的try
    public static int basicMethod(){
        int a=100;
        try {
            a = 1;
            return a;
        }catch (Exception e){
            e.printStackTrace();
            a = 2;
            return a;
        }finally {
            a = 3;
        }
    }

    //返回基本类型的try
    public static int basicMethod_finallyReturn(){
        int a=100;
        try {
            a = 1;
            return a;
        }catch (Exception e){
            e.printStackTrace();
            a = 2;
            return a;
        }finally {
            return a = 3;
        }
    }

    //该内部类作为下面objectMethod方法中try返回的类型
    public static class MyClass{
        public  int var;

        @Override
        public String toString() {
            return "返回值为:"+var;
        }
    }

    //返回对象类型的try
    public static MyClass objectMethod(){
        MyClass myClass = new MyClass();
        try {
            myClass.var = 1;
            return myClass;
        }catch (Exception e){
            e.printStackTrace();
            myClass.var = 2;
            return myClass;
        }finally {
            myClass.var = 3;
        }
    }
    //返回对象类型的try
    public static MyClass objectMethod_finallyReturn(){
        MyClass myClass = new MyClass();
        try {
            myClass.var = 1;
            return myClass;
        }catch (Exception e){
            e.printStackTrace();
            myClass.var = 2;
            return myClass;
        }finally {
            myClass.var = 3;
            return myClass;
        }
    }

    //返回对象类型的try
    public static MyClass objectMethod_catchReturn(){
        MyClass myClass = new MyClass();
        try {
            myClass.var = 1;
             int i = 1/0;
            return myClass;
        }catch (Exception e){
            e.printStackTrace();
            myClass.var = 2;
            return myClass;
        }finally {
            myClass.var = 3;
            return myClass;
        }
    }
}