持有对象---Arrays.asList()和Collections.addAll()的性能比较

Posted 2021-02-03 alagong

• import java.util.ArrayList; 
  import java.util.Arrays; 
  import java.util.Collections; 
  import java.util.List; 
  public class ArraysCompareCollectionsTest { 
  public static void main(String[] args) { 
  int count = 10000000;//通过改变循环次数来放大或放小结果 
  System.out.println("Arrays‘s time is " + arraysTest(count)); 
  System.out.println("Collections‘s time is " + collectionsTest(count)); 
  } 
  public static long arraysTest(int count) { 
  long startTime = System.currentTimeMillis(); 
  for (int i = 0; i < count; i++) { 
  List arrays = new ArrayList (); 
  arrays.addAll(Arrays.asList("hello", "java", "world")); 
  } 
  return System.currentTimeMillis() - startTime; 
  }public static long collectionsTest(int count) { 
  long startTime = System.currentTimeMillis(); 
  for (int i = 0; i < count; i++) { 
  List arrays = new ArrayList (); 
  Collections.addAll(arrays,"hello", "java", "world"); 
  } 
  return System.currentTimeMillis() - startTime; 
  } 
  } 
  

  二、控制台输出结果分析

  
  

  1.当count=100000时,Collections的运行速度比Arrays的要快60ms左右

  
  

  2.当count=1000000时,Collections的运行速度比Arrays的要快100ms左右

  
  

  3.当count=10000000时,Collections的运行速度比Arrays的要快更多

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