【Java提高篇】Java中数组、List和Set的互相转换

【Java提高篇】Java中数组、List和Set的互相转换

1.1、数组转List

String[] staffs &＃61; new String[]{"Tom", "Bob", "Jane"};
List staffsList &＃61; Arrays.asList(staffs);

&＃xff08;1&＃xff09;需要注意的是&＃xff0c; Arrays.asList() 返回一个受指定数组决定的固定大小的列表。所以不能做 add 、 remove 等操作&＃xff0c;否则会报错。例如&＃xff1a;

List staffsList &＃61; Arrays.asList(staffs);
staffsList.add("Mary"); // UnsupportedOperationException
staffsList.remove(0); // UnsupportedOperationException

&＃xff08;2&＃xff09;如果想再做增删操作呢&＃xff1f;将数组中的元素一个一个的添加到列表&＃xff0c;这样列表的长度就不固定了&＃xff0c;可以进行增删操作。

List staffsList &＃61; new ArrayList();
for(String temp: staffs){staffsList.add(temp);
}
staffsList.add("Mary"); // ok
staffsList.remove(0); // ok

1.2、数组转Set

String[] staffs &＃61; new String[]{"Tom", "Bob", "Jane"};
Set staffsSet &＃61; new HashSet<>(Arrays.asList(staffs));
staffsSet.add("Mary"); // ok
staffsSet.remove("Tom"); // ok

2.1、List转数组

String[] staffs &＃61; new String[]{"Tom", "Bob", "Jane"};
List staffsList &＃61; Arrays.asList(staffs);
Object[] result &＃61; staffsList.toArray();

2.2、List转Set

String[] staffs &＃61; new String[]{"Tom", "Bob", "Jane"};
List staffsList &＃61; Arrays.asList(staffs);
Set result &＃61; new HashSet(staffsList);

3.1、Set转List

String[] staffs &＃61; new String[]{"Tom", "Bob", "Jane"};
Set staffsSet &＃61; new HashSet<>(Arrays.asList(staffs));
List result &＃61; new ArrayList<>(staffsSet);


3.2、Set转数组

String[] staffs &＃61; new String[]{"Tom", "Bob", "Jane"};
Set staffsSet &＃61; new HashSet<>(Arrays.asList(staffs));
Object[] result &＃61; staffsSet.toArray();

转自&＃xff1a;https://blog.csdn.net/my_precious/article/details/53010232