import net.sf.json.JSONArray; 
import net.sf.json.JSONObject; 
import java.util.*; 
public class JavaTest { 
public static void main(String[] args){ 
JSONObject obj=new JSONObject(); 
obj.put("derek","23"); 
obj.put("dad", "49"); 
obj.put("mom", "45"); 
System.out.println("通过构造器的方式创建的JSONObject对象："+obj); 
Map<string,string> map=new LinkedHashMap<>(); 
map.put("derek","23"); 
map.put("dad", "49"); 
map.put("mom", "45"); 
System.out.println("通过fromObject方法将map对象转换为JSONObject对象："+JSONObject.fromObject(map)); 
JSONArray arr=new JSONArray(); 
arr.add(0,"derek"); 
arr.add(1,"dad"); 
arr.add(2,"mom"); 
System.out.println("通过构造器的方式创建的JSONArray："+arr); 
ArrayList list=new ArrayList<>(); 
list.add("derek"); 
list.add("dad"); 
list.add("mom"); 
System.out.println("通过fromObject方法将Arraylist对象转换为JSONArray对象："+JSONArray.fromObject(list)); 
System.out.println("将HashMap对象通过fromObject方法转换为JSONArray对象"+JSONArray.fromObject(map)); 
String str="{"derek":23,"dad":49,"mom":45}"; 
System.out.println("解析之后的JSON对象："+JSONObject.fromObject(str)); 
//遍历输出 
Iterator it=obj.keys(); 
while(it.hasNext()){ 
String key=it.next(); 
System.out.println(key+":"+obj.get(key)); 
} 
} 
} 

import java.util.*; 
public class ArrayListTest{ 
public static void main(String dd[]){ 
//new了一个存储list 
List l=new ArrayList(); 
//因为Collection framework只能存储对象所以new封装类 
l.add(new Integer(1)); 
l.add(new Integer(2)); 
l.add(new Integer(3)); 
l.add(new Integer(4)); 
Iterator it=l.iterator(); 
//hasNext是取值取的是当前值.他的运算过程是判断下个是否有值如果有继续. 
while(it.hasNext()){ 
//设it.next封装类,调用Integer的intValue方法返回值为int赋给i; 
int i=((Integer)it.next()).intValue(); 
System.out.println("Element in list is : "+i);}}}