JAVA泛型详解（三）---一个创建常用容器对象的泛型工具类

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import java.util.*;public class ContainerTool{//定义泛型方法，只需要将泛型参数列表置于返回值之前public static <K,V> Map<K,V> map(){return new HashMap<K,V> ();}public static <T> List<T> list(){return new ArrayList<T> ();}public static <T> LinkedList<T> lList(){return new LinkedList<T> ();}public static <T> Set<T> set(){return new HashSet<T> ();}public static <T> Queue<T> queue(){return new LinkedList<T> ();}public static void main(String []args){//测试MapMap<String,List<String>> mList=ContainerTool.map();mList.put("Shape", Arrays.asList("Circle","Square","Triangle"));mList.put("Anaimal", Arrays.asList("Dog","Cat","mouse"));mList.put("Country", Arrays.asList("China","America","Russia"));System.out.println("Map key:  "+mList.keySet());//打印Map的key值System.out.println("Map values:  "+mList.values());//打印Map的valuefor(String key:mList.keySet()){System.out.print(key+"  has: ");for(String value:mList.get(key)){//通过get方法获得Map的每一个Key所对应的valueSystem.out.print("    "+value);}System.out.println();//换行}System.out.println("--------------------------------------------");//测试ListList<String> list=ContainerTool.list();list.addAll(Arrays.asList("dog","dog","cat","mouse","China"));System.out.println("print List:  "+list);System.out.println("--------------------------------------------");//换行//测试setSet<String> set=ContainerTool.set();set.addAll(Arrays.asList("dog","dog","cat","mouse","China"));System.out.println("print Set:   "+set);System.out.println("--------------------------------------------");}}

测试结果如下：

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