我要评论使用linkedhashset删除arraylist中的重复数据(有序)
list<string> words= arrays.aslist("a","b","b","c","c","d");
hashset<string> set=new linkedhashset<>(words);
for(string word:set){
system.out.println(word);
}
使用hashset去重(无序)
//去掉list集合中重复的元素
list<string> words= arrays.aslist("a","b","b","c","c","d");
//方案一：
for(string word:words){
set.add(word);
}
for(string word:set){
system.out.println(word);
}
使用java8新特性stream进行list去重
list<string> words= arrays.aslist("a","b","b","c","c","d");
words.stream().distinct().collect(collectors.tolist()).foreach(system.out::println);
利用list的contains方法循环遍历
list<string> list= new arraylist<>();
for (string s:words) {
if (!list.contains(s)) {
list.add(s);
}
}
注：当数据元素是实体类时，需要额外重写equals()和hashcode()方法。
例如：
以学号为依据判断重复
public class student {
string id;
string name;
int age;
public student(string id, string name, int age) {
this.id = id;
this.name = name;
this.age = age;
}
@override
public boolean equals(object o) {
if (this == o) return true;
if (o == null || getclass() != o.getclass()) return false;
student student = (student) o;
return objects.equals(id, student.id);
}
@override
public int hashcode() {
return id != null ? id.hashcode() : 0;
}
@override
public string tostring() {
return "student{" +
"id='" + id + '\'' +
", name='" + name + '\'' +
", age=" + age +
'}';
}
}
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