Java中数组、List、Set互相转换

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 addremove 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);
posted @ 2018-09-11 20:31  华丽D转身  阅读(2928)  评论(0编辑  收藏  举报