java8 for ,forEach ,Iterator,lambda forEach ,lambda strean forEach , lambda parller stream forEach性能对比
性能结果如下:
lambda parallelStream().forEach() > lambda stream().forEach() ≈ lambda forEach() > classical iterator ≈ classical forEach > classical for
测试代码如下:
1 public class ForTest { 2 public static void main(String[] args) { 3 for( int t=1;t<5;t++){ 4 for(int tt=1;tt<=4;tt++){ 5 ListtestList = Arrays.asList(new Integer[(int) Math.pow(100,(t))]); 6 long t1 = System.currentTimeMillis(); 7 for(int i=0;i {Integer b = integer;});19 long t4 = System.currentTimeMillis();20 21 22 testList.stream().forEach(integer -> {Integer b = integer;});23 long t5 = System.currentTimeMillis();24 25 26 testList.parallelStream().forEach(integer -> {Integer b = integer;});27 long t6 = System.currentTimeMillis();28 29 Integer b;30 for(Iterator iterator = testList.iterator(); iterator.hasNext(); b = iterator.next());31 long t7 = System.currentTimeMillis();32 33 34 System.out.println("x" + tt +": loop size:" + testList.size());35 System.out.println("y" + t + ": classical for loop waste millisecond:"+(t2-t1));36 System.out.println("y" + t + ": classical forEach loop waste millisecond:"+(t3-t2));37 System.out.println("y" + t + ": lambda forEach loop waste millisecond:"+(t4-t3));38 System.out.println("y" + t + ": lambda not parallel stream forEach loop waste millisecond:"+(t5-t4));39 System.out.println("y" + t + ": lambda parallel stream forEach loop waste millisecond:"+(t6-t5));40 System.out.println("y" + t + ": classical iterator loop waste millisecond:"+(t7-t6)+"\n");41 }42 }43 }44 }
测试结果:
x1: loop size:100y1: classical for loop waste millisecond:0y1: classical forEach loop waste millisecond:0y1: lambda forEach loop waste millisecond:74y1: lambda not parallel stream forEach loop waste millisecond:2y1: lambda parallel stream forEach loop waste millisecond:7y1: classical iterator loop waste millisecond:0x2: loop size:100y1: classical for loop waste millisecond:0y1: classical forEach loop waste millisecond:0y1: lambda forEach loop waste millisecond:1y1: lambda not parallel stream forEach loop waste millisecond:0y1: lambda parallel stream forEach loop waste millisecond:0y1: classical iterator loop waste millisecond:0x3: loop size:100y1: classical for loop waste millisecond:1y1: classical forEach loop waste millisecond:0y1: lambda forEach loop waste millisecond:0y1: lambda not parallel stream forEach loop waste millisecond:1y1: lambda parallel stream forEach loop waste millisecond:0y1: classical iterator loop waste millisecond:0x4: loop size:100y1: classical for loop waste millisecond:0y1: classical forEach loop waste millisecond:0y1: lambda forEach loop waste millisecond:0y1: lambda not parallel stream forEach loop waste millisecond:0y1: lambda parallel stream forEach loop waste millisecond:0y1: classical iterator loop waste millisecond:0x1: loop size:10000y2: classical for loop waste millisecond:1y2: classical forEach loop waste millisecond:0y2: lambda forEach loop waste millisecond:1y2: lambda not parallel stream forEach loop waste millisecond:0y2: lambda parallel stream forEach loop waste millisecond:1y2: classical iterator loop waste millisecond:1x2: loop size:10000y2: classical for loop waste millisecond:1y2: classical forEach loop waste millisecond:1y2: lambda forEach loop waste millisecond:0y2: lambda not parallel stream forEach loop waste millisecond:0y2: lambda parallel stream forEach loop waste millisecond:1y2: classical iterator loop waste millisecond:1x3: loop size:10000y2: classical for loop waste millisecond:0y2: classical forEach loop waste millisecond:1y2: lambda forEach loop waste millisecond:0y2: lambda not parallel stream forEach loop waste millisecond:0y2: lambda parallel stream forEach loop waste millisecond:1y2: classical iterator loop waste millisecond:0x4: loop size:10000y2: classical for loop waste millisecond:1y2: classical forEach loop waste millisecond:0y2: lambda forEach loop waste millisecond:0y2: lambda not parallel stream forEach loop waste millisecond:0y2: lambda parallel stream forEach loop waste millisecond:1y2: classical iterator loop waste millisecond:0x1: loop size:1000000y3: classical for loop waste millisecond:14y3: classical forEach loop waste millisecond:9y3: lambda forEach loop waste millisecond:6y3: lambda not parallel stream forEach loop waste millisecond:8y3: lambda parallel stream forEach loop waste millisecond:3y3: classical iterator loop waste millisecond:7x2: loop size:1000000y3: classical for loop waste millisecond:17y3: classical forEach loop waste millisecond:12y3: lambda forEach loop waste millisecond:7y3: lambda not parallel stream forEach loop waste millisecond:0y3: lambda parallel stream forEach loop waste millisecond:1y3: classical iterator loop waste millisecond:18x3: loop size:1000000y3: classical for loop waste millisecond:14y3: classical forEach loop waste millisecond:19y3: lambda forEach loop waste millisecond:0y3: lambda not parallel stream forEach loop waste millisecond:1y3: lambda parallel stream forEach loop waste millisecond:0y3: classical iterator loop waste millisecond:17x4: loop size:1000000y3: classical for loop waste millisecond:13y3: classical forEach loop waste millisecond:25y3: lambda forEach loop waste millisecond:1y3: lambda not parallel stream forEach loop waste millisecond:0y3: lambda parallel stream forEach loop waste millisecond:1y3: classical iterator loop waste millisecond:31x1: loop size:100000000y4: classical for loop waste millisecond:237y4: classical forEach loop waste millisecond:107y4: lambda forEach loop waste millisecond:73y4: lambda not parallel stream forEach loop waste millisecond:70y4: lambda parallel stream forEach loop waste millisecond:28y4: classical iterator loop waste millisecond:98x2: loop size:100000000y4: classical for loop waste millisecond:158y4: classical forEach loop waste millisecond:92y4: lambda forEach loop waste millisecond:59y4: lambda not parallel stream forEach loop waste millisecond:54y4: lambda parallel stream forEach loop waste millisecond:26y4: classical iterator loop waste millisecond:66x3: loop size:100000000y4: classical for loop waste millisecond:123y4: classical forEach loop waste millisecond:67y4: lambda forEach loop waste millisecond:54y4: lambda not parallel stream forEach loop waste millisecond:52y4: lambda parallel stream forEach loop waste millisecond:21y4: classical iterator loop waste millisecond:70x4: loop size:100000000y4: classical for loop waste millisecond:201y4: classical forEach loop waste millisecond:92y4: lambda forEach loop waste millisecond:54y4: lambda not parallel stream forEach loop waste millisecond:53y4: lambda parallel stream forEach loop waste millisecond:23y4: classical iterator loop waste millisecond:67