package ming; import java.util.ArrayList; import java.util.Collection; import java.util.Comparator; import java.util.List; import java.util.TreeSet; /* * 按照hashcode或者length排列 * 以升序排列 * 实现TreeSet * */ class A11 implements Comparator<Object> { @Override //Object为String父类,符合要求 public int compare(Object fst, Object snd) { return hashCode() > snd.hashCode() ? 1 : hashCode() < snd.hashCode() ? -1 : 0; } } public class GenericMethodTest { public static void main(String[] args) { TreeSet<String> ts1 = new TreeSet<String>(new A11()); ts1.add("hello"); ts1.add("wa"); TreeSet<String> ts2 = new TreeSet<String>(new Comparator<String>() { public int compare(String fst, String snd) { return fst.length() > snd.length() ? -1 : fst.length() < snd.length() ? 1 : 0; } }); ts2.add("hello"); ts2.add("wa"); ts2.add("one"); System.out.println(ts1); System.out.println(ts2); } }