集合的一个很重要的操作—遍历，学习了三种遍历方法，三种方法各有优缺点~~
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package cn.tsp2c.liubao;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
/**
*
* @author Administrator
*/
public class TestMap {
public static void main(String[] args) {
Map map = new HashMap();
Student s1 = new Student(“宋江”, “1001″, 38);
Student s2 = new Student(“卢俊义”, “1002″, 35);
Student s3 = new Student(“吴用”, “1003″, 34);
map.put(“1001″, s1);
map.put(“1002″, s2);
map.put(“1003″, s3);
Map subMap = new HashMap();
subMap.put(“1008″, new Student(“tom”, “1008″, 12));
subMap.put(“1009″, new Student(“jerry”, “1009″, 10));
map.putAll(subMap);
work(map);
workByKeySet(map);
workByEntry(map);
}
//最常规的一种遍历方法，最常规就是最常用的，虽然不复杂，但很重要，这是我们最熟悉的，就不多说了！！
public static void work(Map map) {
Collection c = map.values();
Iterator it = c.iterator();
for (; it.hasNext();) {
System.out.println(it.next());
}
}
//利用keyset进行遍历，它的优点在于可以根据你所想要的key值得到你想要的 values，更具灵活性！！
public static void workByKeySet(Map map) {
Set key = map.keySet();
for (Iterator it = key.iterator(); it.hasNext();) {
String s = (String) it.next();
System.out.println(map.get(s));
}
}
//比较复杂的一种遍历在这里，呵呵~~他很暴力哦，它的灵活性太强了，想得到什么就能得到什么~~
public static void workByEntry(Map map) {
Set> set = map.entrySet();
for (Iterator> it = set.iterator(); it.hasNext();) {
Map.Entry entry = (Map.Entry) it.next();
System.out.println(entry.getKey() + “—>” + entry.getValue());
}
}
}
class Student {
private String name;
private String id;
private int age;
public Student(String name, String id, int age) {
this.name = name;
this.id = id;
this.age = age;
}
@Override
public String toString() {
return “Student{” + “name=” + name + “id=” + id + “age=” + age + ‘}’;
}
}