通过HashSet去重(不保证顺序)
public static List<String> getUserList() {
List<String> userList = new ArrayList<>();
userList.add("小王");
userList.add("小张");
userList.add("小詹");
userList.add("小王");
userList.add("老王");
userList.add("小詹");
return userList;
}
@Test
public void removeRepeat1() {
List<String> userList = getUserList();
System.out.println("去重前:" + userList);
Set<String> hashSet = new HashSet<>(userList);
List newList = new ArrayList(hashSet);
System.out.println("去重后:" + newList);
}
通过HashSet去重(保证顺序)
@Test
public void removeRepeat2() {
List<String> userList = getUserList();
System.out.println("去重前:" + userList);
Set set = new HashSet();
List newList = new ArrayList();
for (String str : userList) {
if (set.add(str)) {
newList.add(str);
}
}
System.out.println("去重后:" + newList);
}
遍历后判断赋给另一个list集合去重(保证顺序)
@Test
public void removeRepeat3() {
List<String> userList = getUserList();
System.out.println("去重前:" + userList);
List<String> newList = new ArrayList<String>();
for (String str : userList) {
if (!newList.contains(str)) {
newList.add(str);
}
}
System.out.println("去重后:" + newList);
}
通过TreeSet去重(保证顺序)
@Test
public void removeRepeat4() {
List<String> userList = getUserList();
System.out.println("去重前:" + userList);
Set<String> treeSet = new TreeSet<>();
treeSet.addAll(userList);
List newList = new ArrayList(treeSet);
System.out.println("去重后:" + newList);
}
Java8中Stream流处理(保证顺序)
@Test
public void removeRepeat5() {
List<String> userList = getUserList();
System.out.println("去重前:" + userList);
List newList = userList.stream().distinct().collect(Collectors.toList());
System.out.println("去重后:" + newList);
}