JavaWeb学习笔记-java基础-10-泛型

泛型

List<String> list = new ArrayList<String>();list.add("aaaa");//编译时检查

//泛型集合存取List<String> list = new ArrayList<String>();list.add("aaaa");list.add("bbbb");list.add("cccc");Iterator<String> it = list.iterator();while(it.hasNext()){    String value = it.next();}for(String s : list){    System.out.println(s);}

Map<Integer,String> map = new HashMap<Integer,String>();map.put(1,"aa");map.put(2,"bb");map.put(3,"cc");Set<Map.Entry<Integer,String>> set = map.entrySet();Iterator<Map,Entry<Integer,String>> it =set.iterator();while(it.hashNext()){    Map.Entry<Integer,String> entry = it.netx();    int key = entry.getKey();    String value = entry.getValue(; } for(Map.Entry<Integer,String> entry : map.entrySet()){    int key = entry.getKey();    String value = entry.getValue(;}

//自定义泛型方法//声明泛型在方法上public <T>T a(T t){    return null;}public <T,E,K> void b(T t,E e,K k){}public static <T> void c(T t){}//声明泛型在类上public class Demo<E,F,T>{}