(JAVA)Map集合

package map.demo;


import java.util.*;


public class HashMapDemo {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        HashMap ha = new HashMap<>();
        System.out.println("请输入学生的姓名，年龄，籍贯！");
        System.out.println("例如：'张三 37  黑龙江' ,以空格作为分隔符，以over结束");
        while (true){
            String student = sc.nextLine();
            String []  studentInfo = student.split(" +");

            if (student.equalsIgnoreCase("over")){
                keySet(ha);
                break;
            }
            else{
                ha.put(new Student(studentInfo[0],Integer.parseInt(studentInfo[1])),studentInfo[2]);
            }
        }
    }
    public static void keySet(HashMap mp){
        Set s = mp.keySet();
        Iterator it = s.iterator();
        while (it.hasNext()){
            Student key = it.next();
            String value = mp.get(key);
            System.out.println(key+ "  "+ value);
        }

    }
}






package map.demo;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;


public class Mapdemo {
    public static void main(String[] args) {

        method_4();

    }
    public static void method_4(){
        Map m = new HashMap<>();
        m.put("a",21);
        m.put("b",43);
        m.put("c",90);
        Set> st = m.entrySet();
        Iterator > it = st.iterator();
        while (it.hasNext()){
           Map.Entry  mp = it.next();
          String key = mp.getKey();
          Integer value = mp.getValue();
          System.out.println("key:"+key+"  "+"value:"+value);

        }



    }


    
    public static void method_3(){
        Map m = new HashMap<>();
        m.put("a",21);
        m.put("b",43);
        m.put("c",90);
        Set s = m.keySet();
        Iterator  it = s.iterator();
        while (it.hasNext()){
            String key = it.next();
            Integer value = m.get(key);
            System.out.println("key:"+key+"  "+"value:"+value);
        }

    }


    
    public static void method_2(){
        Map ht = new HashMap<>();
        Integer a = ht.put("a",1);
        Integer b = ht.put("b",2);
        Integer c = ht.put("c",3);
        Integer d = ht.put("d",4);
        Integer i = ht.get("c");
        //判断当前键中是否有某键
        boolean a1 = ht.containsKey("a");
        //判断值中是否包含某值
        boolean b1 = ht.containsValue(3);
        System.out.println(a1+" "+b1);



    }
    
    public static void method(){
        //Map接口对实现类HashMap
        Map h = new HashMap<>();
        //键值对存储到集合的方法，-->put
        Integer a =  h.put("a",1);
        System.out.println(a);
        System.out.println(h);

        //获取键对应的值

    }
    
    public static void method_1(){
        Map ht = new HashMap<>();
        Integer a = ht.put("a",1);
        Integer b = ht.put("b",2);
        Integer c = ht.put("c",3);
        Integer d = ht.put("d",4);
        Integer i = ht.get("c");


        System.out.println("ht:"+ht);
        System.out.println(i);
    }
}

package map.demo;

import java.util.TreeMap;


public class Maptest {
    public static void main(String[] args) {
        String str = "aababcadasda";
        method_1(str);

    }
    public static void method_1(String str){
        char[] strArr =  str.toCharArray();
        TreeMap strArr_treeMap = new TreeMap<>();
        for(char c : strArr){
            Integer i = strArr_treeMap.get(c);
            if (i==null){
                strArr_treeMap.put(c,1);
            }
            else{
                strArr_treeMap.put(c,i+1);
            }
        }
        System.out.println(strArr_treeMap);
    }


}

package map.demo;

import javafx.beans.binding.Mapexpression;

import java.util.*;


public class MapTest2 {
    public static void main(String[] args) {
        HashMap> chuanshi = new HashMap<>();
        HashMap classOne = new HashMap<>();
        HashMap classTwo = new HashMap<>();
        chuanshi.put("功能测试班",classOne);
        chuanshi.put("性能测试班",classTwo);
        classOne.put("001","张三");
        classOne.put("002","李四");
        classTwo.put("003","王二");
        classTwo.put("004","麻子");
        Map_Entry(chuanshi);
    }
    public static void keySet(HashMap> className){
        Set classname = className.keySet();
        Iterator< String> it = classname.iterator();
        while (it.hasNext()){
            String class_id = it.next();
            HashMap class_student_number = className.get(class_id);
            Set class_number = class_student_number.keySet();
            Iterator it_1 = class_number.iterator();
            while (it_1.hasNext()){
                String student_id = it_1.next();
                String student_name = class_student_number.get(student_id);
                System.out.println("Class:"+class_id+"  "+"id:"+ student_id+"  "+"name:"+student_name);
            }
        }
    }
    public static void Map_Entry(HashMap> className){
        //使用具和方法，将键值对关系存储到Set集合
        Set>> mp1 = className.entrySet();

        Iterator>> it = mp1.iterator();
        while(it.hasNext()){
            Map.Entry> mp2 = it.next();
            //获取班级对象
            HashMap mp_class_name = mp2.getValue();
            //获取班级id
            String mp_class_id   = mp2.getKey();

            Set> student_number = mp_class_name.entrySet();
            Iterator> it2 = student_number.iterator();
            while (it2.hasNext()){
                Map.Entrymp3 = it2.next();
                //获取学生姓名
                String mp_student_name = mp3.getValue();
                //获取学生id
                String mp_student_id = mp3.getKey();
                System.out.println("class name:"+ mp_class_id+"  student id:"+mp_student_id+"  student name:"+mp_student_name);

            }




        }
    }
}

package map.demo;

import java.util.*;


class MyComparator implements Comparator {
    public int compare(Student s1,Student s2){
        int age = s1.getAge()- s2.getAge();
        return age==0?s1.getName().compareTo(s2.getName()):age;
    }
}
public class treeMapDemo {
    public static void main(String[] args) {
        method_1();

    }

    public static void method_1() {
        TreeMap treemap = new TreeMap<>(new MyComparator());
        treemap.put(new Student("zhangsag", 23), "深圳");
        treemap.put(new Student("lisi", 26), "北京");
        treemap.put(new Student("wanger", 50), "广州");
        treemap.put(new Student("mazi", 100), "上海");
        Set> s = treemap.entrySet();
        Iterator> it = s.iterator();
        while (it.hasNext()) {
            Map.Entry mp = it.next();
            Student key = mp.getKey();
            String value = mp.getValue();
            System.out.println(key + "  " + value);
        }
    }
}