try catch finally 与return的执行顺序

来源：互联网发布：螺旋管换热器计算软件编辑：程序博客网时间：2024/05/21 19:46

去年笔试的时候遇到的题，当时就不太确定，面试的时候面试官说你回去写写代码试试，然而饿哦只是看了看书，直到今天才总结出来，把所有的代码补上了。

1.try-catch-finally结构后+return
（1）try中无异常

public class Test {    public static  void main(String[] args){        String test = test();        System.out.println("test:"+test);    }    private static String test() {        try{            System.out.println("try");        }catch(Exception e){            System.out.println("catch");        }finally{            System.out.println("finally");        }        return "abc";    }}

执行结果：
try
finally
test:abc
（2）try中有异常

 private static String test() {        try{            System.out.println("try");            String str=null;            str.toString();        }catch(Exception e){            System.out.println("catch");        }finally{            System.out.println("finally");        }        return "abc";    }

执行结果：
try
catch
finally
test:abc
2.try{ return; }catch(){} finally{} +return
（1）try无异常

public class Test {    public static  void main(String[] args){        String test = test();        System.out.println("test:"+test);    }    private static String test() {        try{            System.out.println("try");            return "123";        }catch(Exception e){            System.out.println("catch");        }finally{            System.out.println("finally");        }        return "abc";    }}

运行结果：
try
finally
test:123
（2）try有异常

public class Test {    public static  void main(String[] args){        String test = test();        System.out.println("test:"+test);    }    private static String test() {        try{            System.out.println("try");            String str=null;            str.toString();            return "123";        }catch(Exception e){            System.out.println("catch");        }finally{            System.out.println("finally");        }        return "abc";    }}

运行结果：
try
catch
finally
test:abc
3.try{ } catch(){return;} finally{} +return;

public class Test {    public static  void main(String[] args){        String test = test();        System.out.println("test:"+test);    }    private static String test() {        try{            System.out.println("try");              String str=null;            str.toString();        }catch(Exception e){            System.out.println("catch");             return "456";        }finally{            System.out.println("finally");        }        return "abc";    }}

运行结果：
try
catch
finally
test:456
4.try{ return; }catch(){} finally{return;}
（1）try无异常

public class Test {    public static  void main(String[] args){        String test = test();        System.out.println("test:"+test);    }    private static String test() {        try{            System.out.println("try");              return "123"        }catch(Exception e){            System.out.println("catch");        }finally{            System.out.println("finally");            return "789"        }    }}

运行结果：
try
finally
test:789
（2）try有异常

public class Test {    public static  void main(String[] args){        String test = test();        System.out.println("test:"+test);    }    private static String test() {        try{            System.out.println("try");             String str=null;            str.toString();            return "123";        }catch(Exception e){            System.out.println("catch");        }finally{            System.out.println("finally");            return "789";        }    }}

运行结果：
try
catch
finally
test:789
5.try{} catch(){return;}finally{return;}

public class Test {    public static  void main(String[] args){        String test = test();        System.out.println("test:"+test);    }    private static String test() {        try{            System.out.println("try");             String str=null;            str.toString();              }catch(Exception e){            System.out.println("catch");             return "456";        }finally{            System.out.println("finally");            return "789";        }    }}

运行结果:
try
catch
finally
test:789
6.try{ return;}catch(){return;} finally{return;}
（1）try无异常

public class Test {    public static  void main(String[] args){        String test = test();        System.out.println("test:"+test);    }    private static String test() {        try{            System.out.println("try");             return "123";        }catch(Exception e){            System.out.println("catch");             return "456";        }finally{            System.out.println("finally");            return "789";        }    }}

运行结果：
try
finally
test:789
（2）try有异常

public class Test {    public static  void main(String[] args){        String test = test();        System.out.println("test:"+test);    }    private static String test() {        try{            System.out.println("try");              String str=null;            str.toString();                return "123";        }catch(Exception e){            System.out.println("catch");             return "456";        }finally{            System.out.println("finally");            return "789";        }    }}

运行结果：
try
catch
finally
test:789
总结：
(1)若finally{}中有return，这个先被执行，其余的return都会被屏蔽掉不能执行（当然这种情况下finally{}后就没有return语句了）
(2)若finally{}中无return，这个时候return语句的优先执行的就是try里面，try里面没有return，又进入异常了，就执行catch里面的return,若try，catch，都没有return，就执行finally{}以后的return语句。

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