List 去重的几种方法

🔔HashSet去重

import java.util.HashSet;HashSet<Integer> set = new HashSet<>();
set.add(1);
set.add(2);
set.add(2);
System.out.println(set); // [1, 2]

🔔TreeSet去重

import java.util.TreeSet;TreeSet<Integer> set = new TreeSet<>();  
set.add(2);
set.add(1);
set.add(2);
System.out.println(set); // [1, 2]  

🔔LinkedHashSet去重

import java.util.LinkedHashSet;LinkedHashSet<Integer> set = new LinkedHashSet<>();
set.add(2);
set.add(1); 
set.add(2);
System.out.println(set); // [2, 1]

🔔迭代器去重

import java.util.ArrayList;
import java.util.Iterator;ArrayList<Integer> list = new ArrayList<>();
list.add(1);
list.add(2);
list.add(2);Iterator<Integer> it = list.iterator();
while (it.hasNext()) {Integer i = it.next();if (list.indexOf(i) != list.lastIndexOf(i)) {it.remove();}
}System.out.println(list); // [1]  

🔔Stream去重

import java.util.stream.Collectors;ArrayList<Integer> list = new ArrayList<>();
list.add(1);
list.add(2); 
list.add(2);List<Integer> distinctList = list.stream().distinct().collect(Collectors.toList()); System.out.println(distinctList); // [1, 2]

🔔contains去重

ArrayList<Integer> list = new ArrayList<>();
list.add(1);
list.add(2);
list.add(2);for (Integer i : list) {if (!list.contains(i)) {list.remove(i);}
}System.out.println(list); // [1, 2]

🔔写在最后

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