Contains() по 1 полю

public class Item {
 
    @SerializedName("id")
    private int mId;
 
    @SerializedName("uniq_code")
    private int mUniqCode;
 
    @SerializedName("name")
    private String mName;
 
 
    public Item(int mId, int mUniqCode, String mName) {
        this.mId = mId;
        this.mUniqCode = mUniqCode;
        this.mName = mName;
    }
 
    public int getmId() {
        return mId;
    }
 
    public int getmUniqCode() {
        return mUniqCode;
    }
 
    public String getmName() {
        return mName;
    }
 
    @Override
    public String toString() {
        return "(" + mId + ", " + mUniqCode + ", " + mName + ")";
    }
}

import java.util.Comparator;
import java.util.Set;
import java.util.TreeSet;
 
 
public class ItemSet {
    private static final Comparator<Item> cId = Comparator.comparingInt(Item::getmId);
    private static final Comparator<Item> cCode = Comparator.comparingInt(Item::getmUniqCode);
    private static final Comparator<Item> cName = Comparator.comparing(Item::getmName);
 
    public static void main(String[] args) {
        Set<Item> treeSetId = new TreeSet<>(cId);
        Set<Item> treeSetCode = new TreeSet<>(cCode);
        Set<Item> treeSetName = new TreeSet<>(cName);
        Item[] items = new Item[]{
                new Item(1, 2, "Monday"),
                new Item(1, 2, "Tuesday"),
                new Item(2, 3, "Wednesday"),
                new Item(3, 3, "Wednesday"),
                new Item(4, 5, "Thursday"),
                new Item(5, 5, "Thursday"),
                new Item(5, 6, "Friday")
        };
        for (Item item : items) {
            treeSetId.add(item);
            treeSetCode.add(item);
            treeSetName.add(item);
        }
 
        System.out.println(treeSetId);
        System.out.println(treeSetCode);
        System.out.println(treeSetName);
    }
 
}