Map 主要用于存储键(key)值(value)对，根据键得到值，因此键不允许键重复,但允许值重复。
public static void main(String[] args) {
Map<String, String> map = new HashMap<String, String>();
map.put("a3", "aa");
map.put("a2", "bb");
map.put("b1", "cc");
for (Iterator iterator = map.values().iterator(); iterator.hasNext();) {
String name = (String) iterator.next();
System.out.println(name);
}
}
LinkedHashMap例子：输出的结果为aa，bb，cc
public static void main(String[] args) {
Map<String, String> map = new LinkedHashMap<String, String>();
map.put("a3", "aa");
map.put("a2", "bb");
map.put("b1", "cc");
for (Iterator iterator = map.values().iterator(); iterator.hasNext();) {
String name = (String) iterator.next();
System.out.println(name);
}
}
TreeMap例子：输出的结果为bb,aa,cc
public static void main(String[] args) {
Map<String, String> map = new TreeMap<String, String>(new Comparator<Object>(){
Collator collator = Collator.getInstance();
public int compare(Object o1, Object o2) {
CollationKey key1 = collator.getCollationKey(o1.toString());
CollationKey key2 = collator.getCollationKey(o2.toString());
return key1.compareTo(key2);
//return collator.compare(o1, o2);
}});
map.put("a3", "aa");
map.put("a2", "bb");
map.put("b1", "cc");
for (Iterator iterator = map.values().iterator(); iterator.hasNext();) {
String name = (String) iterator.next();
System.out.println(name);
}
}
HashMap,LinkedHashMap,TreeMap之间的区别
原文：http://www.cnblogs.com/hupp/p/4850260.html