java：ArrayList迴圈遍歷的倆種方法使用 ArrayList取出第i個值
package collection;
import java.util.*;
public class NewArrayList {
public static void main(String[] args) {
List<Student> students = new ArrayList<Student>();
for (int i = 0; i < 6; i++) {
students.add(new Student("Happy"+i,"male"+i,20+i));
}
print(students);
print2(students);
}
//迴圈遍歷①for
public static void print(List<Student> newList){
System.out.println("總資料："+newList.size());
Student student;
for (int i = 0; i < newList.size(); i++) {
student = (Student)newList.get(i);
System.out.println(student.toString());
}
}
//迴圈遍歷①Iterator
public static void print2(List<Student> newList){
System.out.println("總資料："+newList.size());
Iterator<Student> iterator = newList.iterator();
Student student;
while (iterator.hasNext()){
student = (Student)iterator.next();
System.out.println(student.toString());
}
}
}
index表示要取的元素的下標(從0開始)
例如:你想取第一個元素"201";
List grouplist=this.getGroupList();
String s =(String)grouplist.get(0);
此時s="201";
如果要迴圈輸出:
for(int i=0;i<grouplist.size();i++)
System.out.println(grouplist.get(i));