HashMap
...
import java.util.Map;
public class HashMapDemo {
public static void main(String[] args) {
HashMap<Integer,String> map = new HashMap<>();//<>钻石语法
map.put(1,"hahah");
map.put(2,"hehe");
map.put(3,"heihei");
map.put(4,"huihui");
System.out.println(map);
for (Map.Entry <Integer,String> e : map.entrySet()){
System.out.println(e.getKey()+"="+e.getValue());
}
for (Integer i : map.keySet()){
System.out.println(i+"="+map.get(i)+"\t");
}
System.out.println();
for (String v: map.values()){
System.out.println(v+"\t");
}
}
}
...
TreeMap
...
package edu.xcdq.map;
import java.util.Map;
import java.util.TreeMap;
public class TreeMapDemo {
public static void main(String[] args) {
TreeMap<Integer,String> map = new TreeMap<>();
map.put(1,"hahah");
map.put(2,"hehe");
map.put(3,"heihei");
map.put(4,"huihui");
System.out.println(map);
for (Map.Entry<Integer,String>e: map.entrySet()){
System.out.println(e.getKey()+"="+e.getValue()+"\t");
}
System.out.println();
for (Integer i:map.keySet()){
System.out.println(i+"="+map.get(i)+"\t");
}
System.out.println();
for (String v: map.values()){
System.out.println(v+"\t");
}
System.out.println();
System.out.println("firstKey=>"+map.firstKey());
System.out.println("firstEntry=>"+map.firstEntry());
System.out.println("lastKey=>"+map.lastKey());
System.out.println("lastEntry=>"+map.lastEntry());
}
}
...
