Java中array、List、Set互相转换-蒲公英云

Java中array、List、Set互相转换

From: https://www.cnblogs.com/yysbolg/p/9977365.html

数组转List

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String[] staffs = new String[]{"A", "B", "C"};
List staffsList = Arrays.asList(staffs);
//注意: 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("D"); // UnsupportedOperationException
staffsList.remove(0); // UnsupportedOperationException
//一下方式可以进行增删操作。
List staffsList = new ArrayList<String>();
for(String temp: staffs){
　　staffsList.add(temp);
}
staffsList.add("D"); // ok
staffsList.remove(0); // ok

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数组转Set

String[] staffs = new String[]{"A", "B", "C"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));
staffsSet.add("D"); // ok
staffsSet.remove("Tom"); // ok

List转数组

String[] staffs = new String[]{"A", "B", "C"};
List staffsList = Arrays.asList(staffs);
Object[] result = staffsList.toArray();

List转Set

String[] staffs = new String[]{"A", "B", "C"};
List staffsList = Arrays.asList(staffs);
Set result = new HashSet(staffsList);

Set转数组

String[] staffs = new String[]{"A", "B", "C"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));
Object[] result = staffsSet.toArray();

Set转List

String[] staffs = new String[]{"A", "B", "C"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));
List<String> result = new ArrayList<>(staffsSet);