- +在此添加单个AI新笔记
实例化对象 - Object dog = new Dog();
Object dog = new Dog();Dog dog = new Dog();Dog<String,Integer> dog = new Dog<String,Integer>();//泛型，实例化的时候加，编译前就可以判断有没有错误ArrayList<String> doglist = new ArrayList<String>();//泛型，实例化的时候加，编译前就可以判断有没有错误
Map<String,Integer> map = new HashMap<>();map.put("Tom",87);map.put("Jerry",87);//泛型的嵌套Set<Map.Entry<String,Integer>> entry = map.entrySet();Iterator<Map.Entry<String, Integer>> iterator = entry.iterator();while(iterator.hasNext()){Map.Entry<String, Integer> e = iterator.next();String key = e.getKey();Integer value = e.getValue();System.out.println(key + "----" + value);}
jdk7写法：前面加<String,Integer>，后面<>