从Java列表中删除重复项[duplicate]

Question

List<DataRecord> transactionList =new ArrayList<DataRecord>();

其中DataCord是一个类

public class DataRecord {
    [.....]
    private String TUN; 

并且调谐器应该是唯一的

Answer 1

有两种有效的解决方案。

第一个是重写equals方法。只需添加：

public class DataRecord {
    [.....]
    private String TUN; 

    @Override
    public boolean equals(Object o) {
        if (o instanceof DataRecord) {
            DataRecord that = (DataRecord) o;
            return Objects.equals(this.TUN, that.TUN);
        }
        return false;
    }

    @Override
    public int hashCode() {
           return Objects.hashCode(TUN);
    }
}

然后,follwing代码将删除重复项：

List<DataRecord> noDuplicatesList = new ArrayList<>(new HashSet<>(transactionList));

null

Map<String, DataRecord> helper = new HashMap<>();
for (DataRecord dr : transactionList) {
    helper.putIfAbsent(dr.getTUN(), dr);
}
List<DataRecord> noDuplicatesList = new ArrayList<>(helper.values());