前言：
1.声明一个map: Map map = new HashMap();
2.向map中放值,注意：map是key-value的形式存放的.如:
map.put(”sa”,”dd”);
3.从map中取值:String str = map.get(”sa”).toString();结果是:str = ”dd”;
4.遍历一个map，从中取得key 和value
Map map = new HashMap() ;
Iterator it = map.entrySet().iterator() ;
while (it.hasNext())
{
Map.Entry entry = (Map.Entry) it.next() ;
Object key = entry.getKey() ;
Object value = entry.getValue() ;
}
Java代码如下：
package Test01;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
public class Test03 {
public static void main(String[] args){
a();
b();
}
@SuppressWarnings(“unchecked”)
public static void a(){
@SuppressWarnings(“rawtypes”)
Map map = new HashMap();
map.put(“1”,“aa”);
map.put(“2”,“bb”);
map.put(“3”,“cc”);
map.put(“4”,“dd”);
map.put(“5”,“ee”);
map.put(“6”,“ff”);
map.put(“7”,“gg”);
String str = map.get(“5”).toString();
System.out.println(str);
}
@SuppressWarnings(“unchecked”)
public static void b(){
@SuppressWarnings(“rawtypes”)
Map map = new HashMap();
map.put(“1”,“aa”);
map.put(“2”,“bb”);
map.put(“3”,“cc”);
map.put(“4”,“dd”);
map.put(“5”,“ee”);
map.put(“6”,“ff”);
map.put(“7”,“gg”);
@SuppressWarnings(“rawtypes”)
Iterator it = map.entrySet().iterator() ;
while (it.hasNext())
{
@SuppressWarnings(“rawtypes”)
Map.Entry entry = (Map.Entry) it.next() ;
Object key = entry.getKey() ;
Object value = entry.getValue() ;
System.out.print(“[”+key+“、”);
System.out.print(value+“]”);
System.out.print(“,”);
}
}
}
代码运行后效果如下：
