TryCatchFinally+return 总结

Posted 2023-02-17 sshhsun-

finally中有return：如果try正常/或异常，则执行finally中的return

---

如果finally中没有return， 如果try正常，执行tryreturn语句,
如果异常执行catch中return语句，但是此事return语句返回在finally语句之后

---

finally中有错误，应该是直接退出

—上代码！！

package others;

/**
 * finally中有return：如果try正常/或异常，则执行finally中的return
 * 
 * 
 * 如果finally中没有return， 如果try正常，执行tryreturn语句,
 * 如果异常执行catch中return语句，但是此事return语句返回在finally语句之后
 * 
 * 
 * finally中有错误，应该是直接退出
 * 
 * @author sshunsun
 *
 */
public class TryCatchFinally 
    public static void main(String[] args) 
        System.out.println(Test1(1));
        System.out.println("------------------");
        System.out.println(Test1(2));
        System.out.println("~~~~~~~~~~~~~~~");
        System.out.println(Test2(1));
        System.out.println("------------------");
        System.out.println(Test2(2));
        System.out.println("~~~~~~~~~~~~~~~");
        System.out.println(Test3(1));
    

    /**
     * @param num
     * @return finally中有return：如果try正常/或异常，则执行finally中的return
     * 
     */
    public static String Test1(int num) 
        System.out.println("Test1----" + num);
        try 
            System.out.println("start Try");
            if (num == 2) 
                throw new Exception(num + "");
            
            System.out.println("end Try");
            return "return in try";
         catch (Exception e) 
            System.out.println("start Catch");

            System.out.println("end Catch");
            return "return in catch";
         finally 

            System.out.println("start Finally");

            System.out.println("end Finally");
            return "return in finally";
        
    





    /**
     * @param num
     * @return 如果finally中没有return， 如果try正常，执行tryreturn语句,
     *         如果异常执行catch中return语句，但是此事return语句返回在finally语句之后
     *         finally对最终结果不会有影响！！
     */
    public static String Test2(int num) 
        int i = num;
        System.out.println("Test2----" + num);
        try 
            System.out.println("start Try");
            if (num == 2) 
                throw new Exception(num + "");
            
            System.out.println("end Try");
            return "return in try  num:" + i;
         catch (Exception e) 
            System.out.println("start Catch");

            System.out.println("end Catch");
            return "return in catch  num:" + i;
         finally 
            System.out.println("start Finally");
            i = 0; // finally对最终结果不会有影响
            System.out.println("end Finally");
        
    




    /**
     * @param num
     * @return
     * 
     * 
     *         finally中有错误，应该是直接退出
     */
    public static String Test3(int num) 
        int i = num;
        System.out.println("Test3----" + num);
        try 
            System.out.println("start Try");
            if (num == 2) 
                throw new Exception(num + "");
            
            System.out.println("end Try");
            return "return in try  num:" + i;
         catch (Exception e) 
            System.out.println("start Catch");

            System.out.println("end Catch");
            return "return in catch  num:" + i;
         finally 
            System.out.println("start Finally");
            int t = 5 / 0;
            System.out.println("end Finally");

            return "return in finally";
        
    

运行结果：

Test1----1
start Try
end Try
start Finally
end Finally
return in finally
------------------
Test1----2
start Try
start Catch
end Catch
start Finally
end Finally
return in finally
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Test2----1
start Try
end Try
start Finally
end Finally
return in try  num:1
------------------
Test2----2
start Try
start Catch
end Catch
start Finally
end Finally
return in catch  num:2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Test3----1
start Try
end Try
start Finally
Exception in thread "main" java.lang.ArithmeticException: / by zero
    at others.TryCatchFinally.Test3(TryCatchFinally.java:99)
    at others.TryCatchFinally.main(TryCatchFinally.java:23)