TreeSet判断重复元素解析及代码示例

import java.util.TreeSet;
import org.junit.Test;
public class TestTreeSet {
	class Combine implements Comparable<Combine> {
		private int p1;
		private int p2;
		public Combine(int p1, int p2) {
			this.p1 = p1;
			this.p2 = p2;
		}
		@Override
		    public int hashCode() {
			return p1 * 31 + p2;
		}
		@Override
		    public Boolean equals(Object obj) {
			System.out.print("whether equal " + this + " and " + obj);
			Boolean rect = false;
			if (obj instanceof Combine) {
				System.out.println("whether equal " + this + " and " + obj);
				Combine other = (Combine) obj;
				rect = (this.p1 == other.getP1() && this.p2 == other.getP2());
			}
			System.out.println(": " + rect);
			return rect;
		}
		@Override
		    public int compareTo(Combine o) {
			System.out.print("compare " + this + " and " + o);
			// 排序时只考虑p1
			if (this.p1 < o.p1) {
				System.out.println(", return -1");
				return -1;
			} else if (this.p1 > o.p1) {
				System.out.println(", return 1");
				return 1;
			} else {
				System.out.println(", return 0");
				return 0;
			}
		}
		@Override
		    public String toString() {
			return "(" + p1 + "," + p2 + ")";
		}
		public int getP1() {
			return p1;
		}
		public void setP1(int p1) {
			this.p1 = p1;
		}
		public int getP2() {
			return p2;
		}
		public void setP2(int p2) {
			this.p2 = p2;
		}
	}
	@Test
	  public void test() {
		Combine c1 = new Combine(1, 2);
		Combine c2 = new Combine(1, 2);
		Combine c3 = new Combine(1, 3);
		Combine c4 = new Combine(5, 2);
		TreeSet<Combine> set = new TreeSet<Combine>();
		set.add(c1);
		set.add(c2);
		set.add(c3);
		set.add(c4);
		while (!set.isEmpty()) {
			//按顺序输出TreeSet中的元素
			Combine combine = set.pollFirst();
			System.out.println(combine.getP1() + "\t" + combine.getP2());
		}
	}
}