您的密钥必须实现hashCode和equals。如果它是 SortedMap ，则还必须实现Comparable接口
public class MyKey implements Comparable<MyKey>{private Integer i;private String s;public MyKey(Integer i,String s){this.i=i;this.s=s;}public Integer getI() { return i;}public String getS() { return s;}@Overridepublic int hashpre(){return i.hashpre()+31*s.hashpre();}@Overridepublic boolean equals(Object o){if(o==this) return true;if(o==null || !(o instanceof MyKey)) return false;MyKey cp= MyKey.class.cast(o);return i.equals(cp.i) && s.equals(cp.s); } public int compareTo(MyKey cp) { if(cp==this) return 0; int i= i.compareTo(cp.i); if(i!=0) return i; return s.compareTo(cp.s); } @Override public String toString() { return "("+i+";"+s+")"; } }public Map<MyKey,String> map= new HashMap<MyKey,String>();map.put(new MyKey(1,"Hello"),"world");
