finally在try和catch块以及return中的执行顺序

Myth丶恋晨 2022-09-26 14:58 172阅读 0赞

*  执行顺序
    
     *  无catch时
     *  当有catch时
 *  执行顺序图
 *  DEMO验证
 *  参考资料

# 执行顺序 #

## 无catch时 ##

*  finally会在try包含的return之后执行，会在try外面的return之前执行

## 当有catch时 ##

*  finally是在catch执行之后catch包含的return之前执行的

# 执行顺序图 #

try包含的return  
|  
v  
catch  
|  
v  
finally  
|  
v  
catch包含的return  
|  
v  
try外面的return（和catch块不能并存）

# DEMO验证 #

package abc;
    
    /** * @ClassName: Test1 * @Description: TODO(这里用一句话描述这个类的作用) * @author bamboo <a href="mailto:zjcjava@163.com?subject=hello,bamboo&body=Dear Bamboo:%0d%0a描述你的问题：">Bamboo</a> * @date 2017年3月2日 下午2:49:55 * @since */
    
    public class Test1 { 
    
        public static void main(String[] args) {
            // TODO Auto-generated method stub
            testa();
        }
    
    
        public static  Object testa() {
            // TODO Auto-generated method stub
             StringBuffer sb = new StringBuffer("");
    
                try {
                    return print(sb);
                } finally {
                    sb.append("finally");
                    System.out.println(sb.toString());
                }
        }
    
        public static  Object testb() {
            // TODO Auto-generated method stub
             StringBuffer sb = new StringBuffer("");
    
                try {
    
                } finally {
                    sb.append("finally");
                    System.out.println(sb.toString());
                }
                return print(sb);
        }
    
        public static  Object testc() {
            // TODO Auto-generated method stub
             StringBuffer sb = new StringBuffer("");
    
                try {
    
                    int a=1;
                    if(1==a){
                        throw new Exception();
                    }
                    return print(sb);
                }catch(Exception e){
                    sb.append("catch");
                    return print(sb);
                }finally {
                    sb.append("finally");
                    System.out.println(sb.toString());
                }
        }
        public static  Object print(StringBuffer sb) {
            // TODO Auto-generated method stub
                sb.append("return");
              System.out.println(sb.toString());
    
              return null;
        }
    }

testa()方法ouput:

return
    returnfinally

testa()方法是return在try的里面，从结果看先执行的retrun然后执行的finally;

testb()方法ouput:

finally
    finallyreturn

testb()方法是return在try的外面，从结果看先执行的finally然后执行的retrun;

testc()方法ouput:

catchreturn
    catchreturnfinally

testb()方法是return在try的外面，从结果看先执行的finally然后执行的retrun;

# 参考资料 #

[http://www.ibm.com/developerworks/cn/java/j-lo-finally/][http_www.ibm.com_developerworks_cn_java_j-lo-finally]  
finally对基本类型和引用类型参数造成的影响  
[http://blog.csdn.net/imzoer/article/details/8037970][http_blog.csdn.net_imzoer_article_details_8037970]

[http_www.ibm.com_developerworks_cn_java_j-lo-finally]: http://www.ibm.com/developerworks/cn/java/j-lo-finally/
[http_blog.csdn.net_imzoer_article_details_8037970]: http://blog.csdn.net/imzoer/article/details/8037970