本文共 2313 字，大约阅读时间需要 7 分钟。

Main.java

package 泛型;public class Main {
       public static void main(String[]argv){
           var list=new GenericList
   
    ();        list.add(Integer.valueOf(2));        list.add(6);        System.out.println(list.get(1));        var user1=new User(10);        var user2=new User(20);        System.out.println(max(user1,user2));        print(1,2);        /*泛型与继承*/        User user=new Instructor(666);        printUser(user);        var users=new GenericList
    
     ();        //ERROR        //printUsers(users);        //GenericList
     
       并不能转换为 GenericList
      
               /*Wildcards通配符解决，泛型继承问题        * */        printGenericListALL(users);    }    public static 
       
        > T max(T first,T second){
           return first.compareTo(second)<0?second:first;    }    public static 
        
          void print(K key,V value){ System.out.println("key="+key+" value="+value); } /*泛型与继承 *Generic Classes and Inheritance * */ public static void printUser(User user){ System.out.println(user); } public static void printUsers(GenericList
         
           users){ } public static void printGenericListALL(GenericList
           users){ //Object x=users.get(0); }}
         
        
       
      
     
    
   

User.java

package 泛型;public class User implements Comparable
   
    {
       private int point;    public User(int point){
           this.point=point;    }    @Override    public int compareTo(User o) {
           //this < o ->-1        //this==o  ->0        //this > o  ->1        return  point-o.point;    }    @Override    public String toString(){
           return "point="+this.point;    }}
   

KeyValuePair.java

package 泛型;public class KeyValuePair
   
     {
       private K key;    private V value;    public KeyValuePair(K key,V value){
           this.key=key;        this.value=value;    }}
   

Instructor.java

package 泛型;public class Instructor extends User{
       public Instructor(int point){
           super(point);    }}

GenericList.java

package 泛型;/*1、泛型什么样子* */public class GenericList
   
     {
   //public class GenericList
    
     //public class GenericList
     
      //public class GenericList
      
        {
       private T[] items=(T[])new Object[10];    private int count=0;    public void add(T item){
           items[count++]=item;    }    public T get(int index){
           return items[index];    }}
      
     
    
   

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