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Main.java

package 集合框架.Collection接口;/**           Iterable(接口)*           Collection(接口)* List(接口)        Queue(接口)          Set(接口)* ArrayList(接口类)    PriorityQueue (接口类)     HashSet(接口类)* LinkedList(接口类)* */import java.util.Collections;public class Main {
       public static void main(String[]argv){
           //CollectionDemo.show();/*Collection接口*/        //CollectionDemo.listDemo();/*List接口*/        //CollectionDemo.queueDemo();/*Queue接口*/        //CollectionDemo.setDemo();/*Set接口*/        CollectionDemo.hashMapDemo();/*Map接口*/    }}

CollectionDemo.java

package 集合框架.Collection接口;import 泛型.Instructor;import java.util.*;public class CollectionDemo {
       public static void show(){
           /*USE Collection*/        Collection
   
    collection=new ArrayList<>();        /*---添加元素---*/        collection.add("a");        collection.add("b");        collection.add("c");        /*---一次添加多个元素---*/        Collections.addAll(collection,"d","e","f");        /*迭代集合*///        for(var item:collection){
   //            System.out.println(item);//        }        System.out.println(collection);        /*---以除某个元素---*/        collection.remove("a");        System.out.println(collection);        /*---是否包含某个元素---*/        System.out.println(collection.contains("a"));        /*---返回集合元素个数---*/        System.out.println(collection.size());        /*---清空集合---*/        collection.clear();        System.out.println(collection.size());        /*---判断集合是否为空---*/        System.out.println(collection.isEmpty());        /*---将集合元素转换为数组---*/        Object[]objectArray=collection.toArray();        String[]stringArray=collection.toArray(new String[0]);        /*---复制集合---*/        Collection
    
     other=new ArrayList<>();        other.addAll(collection);        /*---比较集合---*/        System.out.println(collection.equals(other));    }    public static void listDemo(){
           List
     
       list=new ArrayList<>();        /*添加元素*/        list.add("a");        list.add("b");        list.add("c");        list.add(3,"3");        /*一次添加多个元素*/        Collections.addAll(list,"d","e","f");        System.out.println(list);        /*获取某个位置的元素*/        System.out.println(list.get(2));        /*重新设置某位置的元素*/        list.set(0,"first");        /*除去元素*/        list.remove(1);        System.out.println(list);        /*寻找元素:第一个出现的位置*/        System.out.println(list.indexOf("first"));        /*寻找元素:最后一次出现的位置*/        System.out.println(list.lastIndexOf("e"));        /*截取List*/        System.out.println(list.subList(0,2));//0 1        /*使用Comparable接口排序*/        List
      
       sortSuches=new ArrayList<>();        sortSuches.add(new SortSuch(23));        sortSuches.add(new SortSuch(13));        sortSuches.add(new SortSuch(103));        Collections.sort(sortSuches);        //System.out.println(sortSuches);        /*Comparator interface比较器接口排序*/        Collections.sort(sortSuches,new sortSuchComparator());        System.out.println(sortSuches);    }    public static void queueDemo(){
           Queue
       
         queue=new ArrayDeque<>();        queue.add("C");//后插        queue.add("B");        queue.add("A");        queue.offer("D");//前插        //后C B A D前        System.out.println(queue);        //获取队列头:不删除        var frontEl=queue.peek();/*队列为空时返回null*/        frontEl=queue.element();/*队列为空时抛出异常*/        System.out.println(frontEl);        //获取队列头并删除队列头        frontEl=queue.remove();/*当队列为空时抛出异常*/        frontEl=queue.poll();/*当队列为空时返回null*/        System.out.println(queue);        queue.poll();        //清空队列        queue.clear();    }    public static  void setDemo(){
           Set
        
         collection=new HashSet<>(); collection.add("a"); collection.add("a"); collection.add("a"); System.out.println(collection);//[a] Collection
         
          collection1=new ArrayList<>(); Collections.addAll(collection1,"a","a","b","b"); Set
          
           set=new HashSet<>(collection1); System.out.println(set);//[a, b] /*集合运算*/ //union collection.addAll(collection1); //Intersection 交运算 collection.removeAll(collection1); //差运算 collection.removeAll(collection1); System.out.println(collection); } public static void hashMapDemo(){ Map
           
            map=new HashMap<>(); map.put("hello",23); map.put("hello2",43); map.put("hello4",53); System.out.println(map.get("hello"));//23 System.out.println(map.get("hellofvd"));//null System.out.println(map.getOrDefault("hellodc",-1));//-1 //判断是否包含某个键 System.out.println(map.containsKey("hello"));//true //遍历 for(var key:map.keySet()){ System.out.println(key); } /* hello4 hello2 hello*/ for(var entry:map.entrySet()){ System.out.println(entry); /*entry.getKey() entry.getValue()*/ } /* hello4=53 hello2=43 hello=23 * */ }}
           
          
         
        
       
      
     
    
   

SortSuch.java

package 集合框架.Collection接口;/*使用Comparable接口排序*/public class SortSuch implements Comparable
   
    {
       @Override    public int compareTo(SortSuch o) {
           /*        * this < other <0        * this==other =0        * this > other >0        * */        return this.money-o.money;    }    public int money;    public SortSuch(int money){
           this.money=money;    }    @Override    public String toString(){
           return String.valueOf(money);    }}
   

sortSuchComparator.java

package 集合框架.Collection接口;import java.util.Comparator;public class sortSuchComparator implements Comparator
   
     {
       @Override    public int compare(SortSuch o1, SortSuch o2) {
           return o1.money-o2.money;    }}
   

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