java list去重

1.不帶類型寫法：

List listWithoutDup = new ArrayList(new HashSet(listWithDup));

2.帶類型寫法：

List<string> listWithoutDup = new ArrayList<string>(new HashSet<string>(listWithDup));
//java 7
<code class="java plain">List<string> listWithoutDup = </code><code class="java keyword">new</code> <code class="java plain">ArrayList<>(</code><code class="java keyword">new</code> <code class="java plain">HashSet<>(listWithDup));</code>

3.例子：

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
 
public class Test {
    public static void main(String[] args) {
        List<string> listWithDup = new ArrayList<string>();
        listWithDup.add("1");
        listWithDup.add("2");
        listWithDup.add("3");
        listWithDup.add("1");
 
        List<string> listWithoutDup = new ArrayList<string>(new HashSet<string>(listWithDup));
        System.out.println("list with dup:"+ listWithDup);
        System.out.println("list without dup:"+ listWithoutDup);
    }
}

樣例運行結果：list with dup:[1, 2, 3, 1]
                            list without dup:[3, 2, 1]

4.原理：

set集合不允許出現重複的值。




代碼引自：點擊打開鏈接