不要在foreach循环里进行元素的add/remove操作

public class ForeachTest {
public static void main(String[] args) {
List<String> a = new ArrayList<>();
a.add("1");
a.add("2");

for (String str : a) {
if("2".equals(str)){
a.remove(str);
}
}

//遍历结果
for (String str : a) {
System.out.println(str);
}
}
}

public class ForeachTest {
public static void main(String[] args) {
List<String> a = new ArrayList<>();
a.add("1");
a.add("2");

Iterator<String> it = a.iterator();
while (it.hasNext()) {
String str = (String) it.next();
if("2".equals(str)){
it.remove();
}
}

//遍历结果
for (String str : a) {
System.out.println(str);
}
}
}