importjava.util.ArrayList;

importjava.util.List;

publicclassForEachMain{

publicstaticvoidmain(String[]args){

//實(shí)例化arrayList

List<Integer>arrayList=newArrayList<Integer>();

intnum=15000000;

//插入10萬條數(shù)據(jù)

for(inti=0;i<num;i++){

arrayList.add(i);

}

List<Integer>res=newArrayList<>();

res.clear();

//用foreach循環(huán)arrayList

longarrayForeachStartTime=System.currentTimeMillis();

for(Integerin:arrayList){

res.add(in);

}

longarrayForeachEndTime=System.currentTimeMillis();

System.out.println(

"用foreach循環(huán)arrayList"+(num)+"次花費(fèi)時(shí)間："+(arrayForeachEndTime-arrayForeachStartTime)+"毫秒");

res.clear();

//用stream-foreach循環(huán)arrayList

longarrayStreamStartTime=System.currentTimeMillis();

arrayList.stream().forEach(e->res.add(e));

longarrayStreamEndTime=System.currentTimeMillis();

System.out.println(

"用Stream-foreach循環(huán)arrayList"+(num)+"次花費(fèi)時(shí)間："+(arrayStreamEndTime-arrayStreamStartTime)+"毫秒");

res.clear();

//用parallelStream-foreach循環(huán)arrayList

longarrayParallelStreamStartTime=System.currentTimeMillis();

arrayList.parallelStream().forEach(e->res.add(e));

longarrayParallelStreamEndTime=System.currentTimeMillis();

System.out.println("用parallelStream-foreach循環(huán)arrayList"+(num)+"萬次花費(fèi)時(shí)間："

+(arrayParallelStreamEndTime-arrayParallelStreamStartTime)+"毫秒");

}

}