try、catch、finally用法总结

try、catch、finally用法总结

1. 无论是否存在异常，finally代码块中的代码都会执行。
2. try代码块中的代码，出现异常的代码之后不会执行。
3. 如果方法存在返回值，那么会先运算return，然后在运行finally代码块。
4. 如果finally代码块中存在return语句，那么程序会提前退出，并且不返回try或者catch代码块中的值。

一：不存在返回值,没有异常信息。

public static void main(String[] args) {
        test01();
        System.out.println("test01 method the end");
    }
    public static void test01() {
        int num = 0;
        try {
            num ++;
            System.out.println("Try the end, num = " + num);
        } catch (Exception e) {
            num ++;
            System.out.println("Catch the end, num = " + num);
        } finally {
            num ++;
            System.out.println("Finally the end, num = " + num);
        }
    }

控制台结果输出

Try the end, num = 1
Catch the end, num = 2
test01 method the end

二：方法存在返回值，无异常信息

public static void main(String[] args) {
        System.out.println("test_01 method the end， num = " + test_01());
    }
    public static int test_01() {
        int num = 0;
        try {
            num ++;
            System.out.println("Try the end, num = " + num);
            return num;
        } catch (Exception e) {
            num ++;
            System.out.println("Catch the end, num = " + num);
            return num;
        } finally {
            num ++;
            System.out.println("Finally the end, num = " + num);
        }
    }

控制台结果输出

Try the end, num = 1
Finally the end, num = 2
test_01 method the end， num = 1

三：finally代码块中存在return

public static void main(String[] args) {
        System.out.println("test_01 method the end， num = " + test_01());
    }
    public static int test_01() {
        int num = 0;
        try {
            num ++;
            System.out.println("Try the end, num = " + num);
            return num;
        } catch (Exception e) {
            num ++;
            System.out.println("Catch the end, num = " + num);
            return num;
        } finally {
            num ++;
            System.out.println("Finally the end, num = " + num);
            return num;
        }
    }

控制台结果输出

Try the end, num = 1
Finally the end, num = 2
test_01 method the end， num = 2