Java异常处理场景中不同位置的返回值详细解析

Java 异常处理中的返回值在不同位置不同场景下是有一些差别的，这里需要格外注意

具体分以下两种场景：

1 finally语句块没有return语句，即当代码执行到try或者catch语句块中的return语句时，相当于在本地保存了一份此时返回值的变量的值副本，然后按照try catch finally的运行机制去执行finally语句块，然后回过来将刚刚保存的副本数据返回

第一个例子为在try中没有异常，直接走到try语句块中的return场景

public class Test01 {

    public static void main(String[] args) {

        int results=new Test01().test(10,2);

        System.out.println("func results:"+results);

    }

    public int test(int a,int b)

    {

        int results=0;

        try

        {

            System.out.println("in try.....");

            results+=1;

            System.out.println("results = "+results);

            return results;

        }

        catch (Exception e)

        {

            System.out.println("in catch......");

            results+=1;

            System.out.println("results = "+results);

            return results;

        }

        finally {

            System.out.println("in finally");

            results+=1;

            System.out.println("results = "+results);

        }

    }

}

执行结果如下，最后函数返回的值是1，而不是2

in try.....

results = 1

in finally

results = 2

func results:1

第二个例子为try中出现了异常，但是在catch中走到了return语句

public class Test01 {

    public static void main(String[] args) {

        int results=new Test01().test(10,2);

        System.out.println("func results:"+results);

    }

    public int test(int a,int b)

    {

        int results=0;

        try

        {

            System.out.println("in try.....");

            results+=1;

            System.out.println("results = "+results);

            double d=1/0;

            return results;

        }

        catch (Exception e)

        {

            System.out.println("in catch......");

            results+=1;

            System.out.println("results = "+results);

            return results;

        }

        finally {

            System.out.println("in finally");

            results+=1;

            System.out.println("results = "+results);

        }

    }

}

返回值如下，即此时返回值是2而不是3

in try.....

results = 1

in catch......

results = 2

in finally

results = 3

func results:2

2 finally语句块有return语句，此时即最终返回finally语句块中的的值，而try或者catch语句块中及时有return语句，也不会发生作用

下面的例子即try中能走到return语句，同样finally中也有return语句时候，此时返回finally语句块中的return的值

public class Test01 {

    public static void main(String[] args) {

        int results=new Test01().test(10,2);

        System.out.println("func results:"+results);

    }

    public int test(int a,int b)

    {

        int results=0;

        try

        {

            System.out.println("in try.....");

            results+=1;

            System.out.println("results = "+results);

            return results;

        }

        catch (Exception e)

        {

            System.out.println("in catch......");

            results+=1;

            System.out.println("results = "+results);

            return results;

        }

        finally {

            System.out.println("in finally");

            results+=1;

            System.out.println("results = "+results);

            return results;

        }

    }

}

执行结果如下，返回2，此时不是返回1了

in try.....

results = 1

in finally

results = 2

func results:2

下面的例子即在catch走到了return语句，同样在finally语句块中也走到了return语句，此时同样也是返回finally语句块中的值，catch语句块中的返回值失效

public class Test01 {

    public static void main(String[] args) {

        int results=new Test01().test(10,2);

        System.out.println("func results:"+results);

    }

    public int test(int a,int b)

    {

        int results=0;

        try

        {

            System.out.println("in try.....");

            results+=1;

            System.out.println("results = "+results);

            double d=1/0;

            return results;

        }

        catch (Exception e)

        {

            System.out.println("in catch......");

            results+=1;

            System.out.println("results = "+results);

            return results;

        }

        finally {

            System.out.println("in finally");

            results+=1;

            System.out.println("results = "+results);

            return results;

        }

    }

}

执行结果如下：返回3而不是2了

in try.....

results = 1

in catch......

results = 2

in finally

results = 3

func results:3

巴特西

Java异常处理场景中不同位置的返回值详细解析

Java 异常处理中的返回值在不同位置不同场景下是有一些差别的，这里需要格外注意

最新文章

热门文章