增强循环:
public static void main(String[] args) {
ArrayList<Integer> list = Lists.newArrayList(1, 2, 3, 4, 5);
list.forEach(e -> {
if (1 == e) {
System.out.println(e);
list.remove(e);
}
});
System.out.println(list);
}
public static void main(String[] args) {
ArrayList<Integer> list = Lists.newArrayList(1, 2, 3, 4, 5);
for (Integer e : list) {
if (1 == e) {
System.out.println(e);
list.remove(e);
}
}
System.out.println(list);
}
上面两种代码会包如下错误:
正确方法:
1常规循环:
public static void main(String[] args) {
ArrayList<Integer> list = Lists.newArrayList(5, 1, 3, 4, 6);
for (int i = 0; i < list.size(); i++) {
if (1 == list.get(i)) {
System.out.println(list.get(i));
list.remove(i);
}
if (5 == list.get(i)) {
System.out.println(list.get(i));
list.remove(i);
// 或者 list.remove(list.get(i));
}
}
System.out.println(list);
}
注:上面这种方法可以删除元素,但是删除的同时索引在增加,列表的size在减小,导致最后会漏删,比如下面的运行结果1就没有删除掉。这种适合只删除一条数据的情况
2迭代器:
public static void main(String[] args) {
ArrayList<Integer> list = Lists.newArrayList(5, 1, 3, 4, 6);
Iterator<Integer> iterator = list.iterator();
while (iterator.hasNext()) {
Integer next = iterator.next();
if (1 == next) {
System.out.println(next);
iterator.remove();
}
if (5 == next) {
System.out.println(next);
iterator.remove();
}
}
System.out.println(list);
}
这种方式可以正常的循环和删除