使用foreach之前要判断是否为空
作者:互联网
public static void main(String[] args) { List<DemoClass> demos = null; for (DemoClass demo : demos) { System.out.println("123"); } }
list.size()>0就行
public static void main(String[] args) {
DemoClass dc=null;
List<DemoClass> demos = new ArrayList();
demos.add(dc);
System.out.println(demos.size());
for (DemoClass demo : demos) {
System.out.println("123");
}
}
标签:判断,DemoClass,System,demos,foreach,为空,println,size,out 来源: https://www.cnblogs.com/sjj33sda/p/13897936.html