arraylist-lambada-性能测试

Posted 2021-01-26 mrerror

package cn.com.one;
import java.util.ArrayList;
public class ttt {
    public static void main(String [] args) {        
        new Thread(()->{
            Thread.currentThread().setName("t2");
            int k =0;
            String test2 = "";
            long startTime2 = System.currentTimeMillis();
            ArrayList<Object> arrayList2= new ArrayList<>(10);
            while(true){
                k += 1;
                test2 = "我是第"+k+"个";
                arrayList2.add(test2);
                if(k > 10000000)  break;
            }
            long overTime2 = System.currentTimeMillis();
            System.out.println(Thread.currentThread().getName()+(overTime2 - startTime2) / 1000+"s");
        }).start();
//----------------------------------------------------------------------------------------------------
        Runnable runnable =  ()->{
            Thread.currentThread().setName("t1");
            int j =0;
            String test1 = "";
            long startTime1 = System.currentTimeMillis();
            ArrayList<Object> arrayList1 = new ArrayList<>(100);
            while (true) {
                j += 1;
                test1 = "我是第" + j + "个";
                arrayList1.add(test1);
                if (j > 10000000) break;
            }
            long overTime1 = System.currentTimeMillis();
            System.out.println(Thread.currentThread().getName()+(overTime1 - startTime1) / 1000 + "s");
        };
//----------------------------------------------------------------------------------------------------
        Thread.currentThread().setName("tmain");
        int i =0;
        String test0 = "";
        long startTime0 = System.currentTimeMillis();
        ArrayList<Object> arrayList0= new ArrayList<>(1);
        while(true){
            i += 1;
            test0 = "我是第"+i+"个";
            arrayList0.add(test0);
            if(i > 10000000)  break;
        }
        long overTime0 = System.currentTimeMillis();
        System.out.println(Thread.currentThread().getName()+(overTime0 - startTime0) / 1000+"s");
//----------------------------------------------------------------------------------------------------
    }
}