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import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
public class Sample {
Calendar cal = Calendar.getInstance();
void getData(ArrayList<InvoiceBillingProjects> projectDataList){
//System.out.println("start");
long start = System.nanoTime();
Iterator<InvoiceBillingProjects> itr = projectDataList.iterator();
while(itr.hasNext()){
// InvoiceBillingProjects ibpp = itr.next();
itr.next().getDescription();
}
/*for(int i=0;i<projectDataList.size();i++){
projectDataList.get(i).getDescription();
}*/
long end = System.nanoTime();
System.out.println(" time "+(end-start));
}
public static void main(String arg[]) {
ArrayList<InvoiceBillingProjects> projectDataList = new ArrayList<InvoiceBillingProjects>();
List<InvAssociateDetails> lt = new LinkedList<InvAssociateDetails>();
for(int i=0;i<120000;i++){
lt.add(new InvAssociateDetails());
//new InvoiceBillingProjects().setAssociateList(lt);
}
for(int i=0;i<120000;i++){
InvoiceBillingProjects ibp = new InvoiceBillingProjects();
projectDataList.add(ibp);
ibp.setAssociateList(lt);
}
new Sample().getData(projectDataList);
}
}
使用迭代器時,搜索整個列表時應比使用for循環時更快。上面的程序顯示了迭代開始和結束之間的時間更長。爲什麼使用迭代器需要更多時間?使用迭代器和for循環在列表中搜索:時間複雜度
謝謝ArthuruhtrA,我知道了,因爲我期待的結果將會是這種情況,如果我使用列表的實現列表LinkedList和NOT數組列表。我的錯 :) –