Set集合和数组转换

集合转数组:

public void setToArray() {
    Set<String> set = new HashSet<>();
 
    //错误！！！！！
    String[] strsFalse = (String[]) set.toArray();
    for (String str : strsFalse) {
        System.out.println(str);
    }
 
    //正确
    String[] strsTrue = set.toArray(new String[set.size()]);
    for(String str:strsTrue){
        System.out.println(str);
    }
}

集合转数组：

 

Set<String> set = new HashSet<>();
String[] arr = set.toArray(new String[set.size()]);