Java学习中关于泛型3

小鱼儿 2022-06-11 08:11 133阅读 0赞

泛型嵌套：

代码如下：

package gen03;
    
    public class Student<T> {
    	private T score;
    
    	public T getScore() {
    		return score;
    	}
    
    	public void setScore(T score) {
    		this.score = score;
    	}
    	
    }

package gen03;
    
    public class OurClass<T> {
    	T stu;
    
    	public T getStu() {
    		return stu;
    	}
    
    	public void setStu(T stu) {
    		this.stu = stu;
    	}
    	
    }

package gen03;
    
    import java.util.HashMap;
    import java.util.Map;
    import java.util.Map.Entry;
    import java.util.Set;
    
    /**
     * 泛型嵌套-->由外到内拆分
     * @author hanjiangbo
     *
     */
    public class StudentApp {
    	public static void main(String[] args) {
    		Student<String> stu = new Student<String>();
    		stu.setScore("优秀");
    		System.out.println(stu.getScore());
    		
    		
    		//泛型嵌套
    		OurClass<Student<String>> ourclass = new OurClass<Student<String>>();
    		ourclass.setStu(stu);
    		stu = ourclass.getStu();
    		
    		String score = stu.getScore();
    		System.out.println(score);
    		
    		
    		//HasMap-->使用了泛型的嵌套
    		Map<String,String> map = new HashMap<String,String>();
    		map.put("a", "csdn");
    		map.put("b", "CSDN");
    		
    		Set<Entry<String,String>> entrySet = map.entrySet();
    		
    		for(Entry<String,String> entry:entrySet) {
    			String key = entry.getKey();
    			String value = entry.getValue();
    			System.out.println(key + "-->" + value);
    		}
    		
    	}
    }

泛型没有多态

泛型没有数组

package gen03;
    
    import java.util.ArrayList;
    import java.util.List;
    
    /**
     * 1、泛型没有多态
     * 2、泛型没有数组
     * @author hanjiangbo
     *
     */
    public class Polymorphism {
    
    	public static void main(String[] args) {
    		//多态
    		Fruit f = new Apple();
    		//泛型没有多态
    		//List<Fruit> list = new ArrayList<Apple>();
    		List<? extends Fruit> list = new ArrayList<Apple>();
    		//泛型没有数组
    		//Fruit<String>[] arr = new Fruit<String>[10];
    		
    	}
    
    }