int Integer String 性能开销

待我称王封你为后i 2021-09-21 11:42 267阅读 0赞

针对int integer string的值比较堆内存的消耗,做一篇总结

public static void StringTest(){ 
            /** * 获取时间 */
            Calendar Cld = Calendar.getInstance();
            int YY = Cld.get(Calendar.YEAR) ;
            int MM = Cld.get(Calendar.MONTH)+1;
            int DD = Cld.get(Calendar.DATE);
            int HH = Cld.get(Calendar.HOUR_OF_DAY);
            int mm = Cld.get(Calendar.MINUTE);
            int SS = Cld.get(Calendar.SECOND);
            int MI = Cld.get(Calendar.MILLISECOND);
            int a = 1;
            int b = 1;
            System.out.println(new SimpleDateFormat("yyyy/MM/dd-HH:mm:ss:SSS").format(new Date()));
            for (int j = 0; j < 10; j++) { 
                for (int i = 0; i < 2147483647; i++) { 
                    if(a==b){ 
                        //System.out.println(true);
                    }else{ 
                        //System.out.println(false);
                    }
                }
            }
            System.out.println(new SimpleDateFormat("yyyy/MM/dd-HH:mm:ss:SSS").format(new Date()));
        }

2020/09/23-20:58:01:195
    2020/09/23-20:58:01:205
    时间开销:10

将上述
    	   int a = 1;
           int b = 1;
           更换为
           Integer a = 1;
           Integer b = 1;
           得到:
           2020/09/23-20:59:02:105
           2020/09/23-20:59:02:115
           时间开销:10
           将==更换为equals
           2020/09/23-21:01:35:135
       	   2020/09/23-21:01:35:145
       	时间开销:10

String a = "1";
           String b = "1";
           System.out.println(new SimpleDateFormat("yyyy/MM/dd-HH:mm:ss:SSS").format(new Date()));
           for (int j = 0; j < 10; j++) { 
               for (int i = 0; i < 2147483647; i++) { 
                   if((a==b)){ 
                   }else{ 
                   }
               }
           }

2020/09/23-21:03:17:354
    2020/09/23-21:03:17:364
    时间开销:10

String a = "1";
           String b = "1";
           System.out.println(new SimpleDateFormat("yyyy/MM/dd-HH:mm:ss:SSS").format(new Date()));
           for (int j = 0; j < 10; j++) { 
               for (int i = 0; i < 2147483647; i++) { 
                   if((a.equals(b))){ 
                   }else{ 
                   }
               }
           }

2020/09/23-21:06:13:304
    2020/09/23-21:06:20:832
    时间开销:7.528

得到:  
integer int string 使用==消耗差距不大,可以忽略不计,  
integer使用equals消耗也很小,但是string相对integer消耗非常大.