java HashMap--介绍及遍历

HashMap 包含键-值对，它实现了Map接口。HashMap和HashTable很相似。只有两点不同，就是HashMap不是线程安全的（即非synchronized），而且它允许null值。HashMap通常是用来做键-值映射的。

另外，HashMap中的元素是无序的。

HashMap举例：

hmap = new HashMap();

hmap.put(12, "Chaitanya");
hmap.put(2, "Rahul");
hmap.put(7, "Singh");
hmap.put(49, "Ajeet");
hmap.put(3, "Anuj");

//遍历
Set set = hmap.entrySet();
Iterator iterator = set.iterator();
while(iterator.hasNext()) {
Map.Entry mentry = (Map.Entry)iterator.next();
System.out.print("key is: "+ mentry.getKey() + " & Value is: ");
System.out.println(mentry.getValue());
}

String var= hmap.get(2);
System.out.println("索引为2的值为: "+var);

hmap.remove(3);

Set set2 = hmap.entrySet();
Iterator iterator2 = set2.iterator();
while(iterator2.hasNext()) {
Map.Entry mentry2 = (Map.Entry)iterator2.next();
System.out.print("Key是: "+mentry2.getKey() + " & Value是: ");
System.out.println(mentry2.getValue());
}

}
}" data-snippet-id="ext.b20da1ebfe1c3e067411042280bd0aaa" data-snippet-saved="false" data-codota-status="done">[code]import java.util.HashMap;
import java.util.Map;
import java.util.Iterator;
import java.util.Set;
public class Details {

public static void main(String args[]) {

HashMap<Integer, String> hmap = new HashMap<Integer, String>();

hmap.put(12, "Chaitanya");
hmap.put(2, "Rahul");
hmap.put(7, "Singh");
hmap.put(49, "Ajeet");
hmap.put(3, "Anuj");

//遍历
Set set = hmap.entrySet();
Iterator iterator = set.iterator();
while(iterator.hasNext()) {
Map.Entry mentry = (Map.Entry)iterator.next();
System.out.print("key is: "+ mentry.getKey() + " & Value is: ");
System.out.println(mentry.getValue());
}

String var= hmap.get(2);
System.out.println("索引为2的值为: "+var);

hmap.remove(3);

Set set2 = hmap.entrySet();
Iterator iterator2 = set2.iterator();
while(iterator2.hasNext()) {
Map.Entry mentry2 = (Map.Entry)iterator2.next();
System.out.print("Key是: "+mentry2.getKey() + " & Value是: ");
System.out.println(mentry2.getValue());
}

}
}