public static void main(String[] args) {
// SpringApplication.run(DemoApplication.class, args);
Map<String, String> map = new HashMap<String, String>();
map.put("xiaocui1", "gongchen");
map.put("xiaocui2", "daima");
map.put("xiaocui3", "xuexi");
map.put("xiaocui4", "dagong");
map.put("xiaocui5", "dagong");
Set<String> strings = map.keySet();
System.out.println(strings.toArray());
String[] keys = map.keySet().toArray(new String[0]);
for (String key: keys) {
System.out.println(key);
}
System.out.println("-----分割线-----");
}
为什么需要 new String[0] 有什么作用,为什么参数是0
上面的程序执行结果