java链表排序

 package struct;import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.TreeSet;public class Comp implements Comparator<Comp>{ private int x; private int y; @Override public int compare(Comp o1, Comp o2) {  return o1.x-o2.x; } Comp(){}  Comp(int x,int y) {  this.x=x;  this.y=y; }  @Override public String toString() {  // TODO Auto-generated method stub  return x+" "+y; } public static void main(String []args) {  Comp c1 = new Comp(3,3);  Comp c2 = new Comp(1,1);  Comp c3 = new Comp(5,3);  Comp c4 = new Comp(4,3);  ArrayList<Comp> list = new ArrayList<Comp>();  list.add(c1);  list.add(c2);  list.add(c3);  list.add(c4);  for (Comp comp : list) {   System.out.println(comp);  }  System.out.println();  Collections.sort(list,new Comp());  for (Comp comp : list) {   System.out.println(comp);  }   }}