Java中陣列、List、Set互相轉換
阿新 • • 發佈:2019-01-04
陣列轉List
String[] staffs = new String[]{"Tom", "Bob", "Jane"};
List staffsList = Arrays.asList(staffs);
需要注意的是,
Arrays.asList()
返回一個受指定陣列決定的固定大小的列表。所以不能做add
、remove
等操作,否則會報錯。List staffsList = Arrays.asList(staffs); staffsList.add("Mary"); // UnsupportedOperationException staffsList.remove(0); // UnsupportedOperationException
如果想再做增刪操作呢?將陣列中的元素一個一個新增到列表,這樣列表的長度就不固定了,可以進行增刪操作。
List staffsList = new ArrayList<String>(); for(String temp: staffs){ staffsList.add(temp); } staffsList.add("Mary"); // ok staffsList.remove(0); // ok
陣列轉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轉陣列
String[] staffs = new String[]{"Tom", "Bob", "Jane"};
List staffsList = Arrays.asList(staffs);
Object[] result = staffsList.toArray();
List轉Set
String[] staffs = new String[]{"Tom" , "Bob", "Jane"};
List staffsList = Arrays.asList(staffs);
Set result = new HashSet(staffsList);
Set轉陣列
String[] staffs = new String[]{"Tom", "Bob", "Jane"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));
Object[] result = staffsSet.toArray();
Set轉List
String[] staffs = new String[]{"Tom", "Bob", "Jane"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));
List<String> result = new ArrayList<>(staffsSet);