Java List去重方法,引用类型集合去重

时间:2022-04-17 20:47:31


一、实体类中要重写比较方法equals,最好也重写hashcode方法


public class WorkWeightDto implements Serializable {

private static final long serialVersionUID = 8245791221237374426L;

// @Id 没有加id自增长策略 会影响到别的实体数据插入。
private String id;
private String projectId; // 项目Id
private String projectName; // 项目
private String startTime; // 开始时间
private String endTime; // 结束时间
private String managerId; // 负责人Id

public WorkWeightDto() {
}

public WorkWeightDto(String id, String projectId, String startTime) {
this.id = id;
this.projectId = projectId;
this.startTime = startTime;
}

@Override
public boolean equals(Object o) {

if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
WorkWeightDto ww = (WorkWeightDto) o;
if (id.equals(ww.getId()) && projectId.equals(ww.getProjectId()) && startTime.equals(ww.getStartTime())){
return true;
}
return false;
}

@Override
public int hashCode() {
return id.hashCode() + projectId.hashCode()+startTime.hashCode();
}


二、去重方法实现

 private List<WorkWeightDto> deleteSame(List<WorkWeightDto> dtoList){

Iterator<WorkWeightDto> it = dtoList.iterator();
WorkWeightDto next =null;
List<WorkWeightDto> newList = new ArrayList<WorkWeightDto>();
while(it.hasNext()){
next = it.next();
if(!newList.contains(next)){
newList.add(next);
}
}
return newList;
}

三、其它方法参见: 集合去重方法A  、  集合去重方法B