数组转不同类型的集合

//定义字符串
String str = "1,3,6,9,4,2,1,6";
//截取字符串
String[] strArr = str.split(",");
//转换long类型的数组
long[] strArrNum = (long[]) ConvertUtils.convert(idsArr,long.class);


数组转List
String[] staffs = new String[]{"Tom", "Bob", "Jane"};
List staffsList = Arrays.asList(staffs);

需要注意的是， 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，否则会报错。

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

如果想再做增删操作呢？将数组中的元素一个一个添加到列表，这样列表的长度就不固定了，可以进行增删操作。

List staffsList = new ArrayList<String>();
for(String temp: staffs){
  staffsList.add(temp);
}
staffsList.add("Mary"); // ok
staffsList.remove(0); // ok

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


List转数组
String[] staffs = new String[]{"Tom", "Bob", "Jane"};
List staffsList = Arrays.asList(staffs);

Object[] result = staffsList.toArray();

List转Set
String[] staffs = new String[]{"Tom", "Bob", "Jane"};
List staffsList = Arrays.asList(staffs);

Set result = new HashSet(staffsList);

Set转数组
String[] staffs = new String[]{"Tom", "Bob", "Jane"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));

Object[] result = staffsSet.toArray();

Set转List
String[] staffs = new String[]{"Tom", "Bob", "Jane"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));

List<String> result = new ArrayList<>(staffsSet);