List remove的三种正确方法

1、倒序循环，因为list删除只会导致当前元素之后的元素位置发生改变，所以采用倒序可以保证前面的元素没有变化；

for(int i=list.size()-1;i>=0;i--){ list.remove(i); 
}

2、顺序循环时，删除当前位置的值，下一个值就会补到当前位置，所以需要执行i–操作；

for (int i=0; i<list.size(); i++) {if (list.get(i) == 3) {list.remove(i);i--;}}    

3、注意必须用迭代器的remove()方法，不要用list的remove，不然会发生java.util.ConcurrentModificationException 异常；

if (null != list && list.size() > 0) {Iterator it = list.iterator();  while(it.hasNext()){Student stu = (Student)it.next(); if (stu.getStudentId() == studentId) {it.remove(); //移除该对象}}
}

代码

package List;import java.util.ArrayList;
import java.util.List;public class List3 {public static void main(String[] args) {List<Integer> list = new ArrayList<>();list.add(1);list.add(1);list.add(2);list.add(3);System.out.println("list = " + list);list.remove(1);System.out.println("list = " + list);list.remove(2);System.out.println("list = " + list);System.out.println();List<Integer> list2 = new ArrayList<>();list2.add(7);list2.add(8);list2.add(9);list2.add(10);list2.add(11);System.out.println("list2 = " + list2);for (int i = 0; i < list2.size(); i++) {System.out.println("list2.get(i) = " + list2.get(i));//7,9,11list2.remove(i);}System.out.println("list2 = " + list2);//8,10System.out.println();List<Integer> list3 = new ArrayList<>();list3.add(7);list3.add(8);list3.add(9);list3.add(10);list3.add(11);System.out.println("list3 = " + list3);for (int i = list3.size() - 1; i >= 0; i--) {System.out.println("list3.get(i) = " + list3.get(i));//11,10,9,8,7list3.remove(i);}System.out.println("list3 = " + list3);System.out.println();List<Integer> list4 = new ArrayList<>();list4.add(7);list4.add(8);list4.add(9);list4.add(10);list4.add(11);System.out.println("list4 = " + list4);for (int i = 0; i < list4.size(); i++) {System.out.println("list4.get(i) = " + list4.get(i));//7, 8, 9, 10, 11list4.remove(i);i--;}System.out.println("list4 = " + list4);System.out.println();}
}