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  • Map集合

    ---恢复内容结束---

     

    package workhome;

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

public class MapDemo {
    public static void main(String[] args) {
        Map<Integer, String> map=new HashMap<Integer,String>();
        map.put(100,"tom100");
        map.put(200,"tom200");
        map.put(300,"tom300");
        System.out.println(map.size());
        
        map.remove(300);
        //迭代
        Set<Entry<Integer,String>> entires=map.entrySet();
        for(Entry<Integer,String> entry :entires) {
            Integer key=entry.getKey();
            String value = entry.getValue();
            System.out.println(key+"-"+value);
        }
        
        //
        System.out.println(map.get(100));
        
        //2.通过key迭代
        Set<Integer> keys = map.keySet();
        for(Integer key:keys) {
            System.out.println(key+"=="+map.get(key));
        }
    }
}
    基本用法

    重写equals和hashcode方法

    package workhome;

import java.util.HashMap;
import java.util.Map;

public class MapDemo2 {
    public static void main(String[] args) {
        Map<MyKey,Cat> map=new HashMap<MyKey, Cat>();
        map.put(new MyKey("tom-1"), new Cat("tom-1",12));
        map.put(new MyKey("tom-2"), new Cat("tom-1",13));
        map.put(new MyKey("tom-3"), new Cat("tom-1",14));
        
        Cat c=map.get(new MyKey("tom-1"));
        System.out.println(c);
        
        System.out.println(map.size());
    }        
}
class Cat{
    private String name;
    private int  height;
    
    
    public Cat(String name, int height) {
        super();
        this.name = name;
        this.height = height;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getHeight() {
        return height;
    }
    public void setHeight(int height) {
        this.height = height;
    }
    
}

class MyKey{
    private String name;
    private Integer age;
    
    MyKey(String name){
        super();
        this.name=name;
    }
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    @Override
    public int hashCode() {
        int namehash= name==null ? 0 :name.hashCode();
        int agehash=age==null? 0 : age.intValue();
        return namehash+agehash;
    }
    
    @Override
    public boolean equals(Object obj) {
        MyKey key0=(MyKey)obj;
        return name.equals(key0.name) && age==key0.age;
    }
}
    HashMap
    package workhome;

import java.util.HashSet;
import java.util.Set;

public class setDemo2 {
    public static void main(String[] args) {
        Set<Dog2> dogs=new HashSet<Dog2>();
        dogs.add((new Dog2("white")));
        dogs.add(new Dog2("white"));
        System.out.println(dogs.size());
        //System.out.println(dogs.contains(new Dog("white")));
    }
}


class Dog2{
    private String name;
    Dog2(String name){
        super();
        this.name=name;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public int hashCode() {
        return 1;
    }
    @Override
    public boolean equals(Object obj) {
        return true;
    }
}
    Hashset

    　

     

    package base;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class CollectionToolDemo {
    public static void main(String[] args) {
        int[] src= {1,2,3,4};
        int[] desc=new int[6];
        System.arraycopy(src, 1, desc, 2,3);
        System.out.println(desc);
        
        Person[] src0= {new Person(100),new Person(200),new Person(300),new Person(400)};
        Person[] dest=new Person[6];
        System.arraycopy(src0, 1, dest, 2, 3);
    
    
    src[2]=1000;
    System.out.println(dest[3]);
    
    src0[2].setHeight(1000);
    System.out.println(dest[3].getHeight());
    
    //
    List<String> names=Collections.synchronizedList(new ArrayList<String>());
    names.add("tom");
    names.add("tom");
    names.add("tom");
    System.out.println(names.size());
    
    //最大值,最小值
    //Collections.max() min()
    //排序
    //Collections.sort(list, c);
    //asList将参数转换成Array$ArrayList集合对象
    List list=Arrays.asList(1,2,3,4);
    //排序
    //Arrays.sort(list);
    
    //Arrays.binarySearch(a, key)
    System.out.println(list.size());
    
    }
}
    ollectionTool
    package base;

import java.util.Hashtable;

public class HashTableDemo {
    public static void main(String[] args) {
        Hashtable<String,Person> ht=new Hashtable<String,Person>();
        ht.put("tom1", new Person(100));
        ht.put("tom1", new Person(100));
        ht.put("tom2", new Person(100));
        ht.put("tom3", new Person(100));
        System.out.println(ht.size());
    }
}
    HashTable
    package base;

import java.util.ArrayList;
import java.util.List;

/**
 * 
 * @author ASUS
 *
 */
public class Person {
    private int height;
    private List<String> tels=new ArrayList<String>();
    
    
    public Person(int height) {
        super();
        this.height = height;
    }

    
    public List<String> getTels() {
        return tels;
    }


    public void setTels(List<String> tels) {
        this.tels = tels;
    }


    public int getHeight() {
        return height;
    }
    
    public void setHeight(int height) {
        this.height = height;
    }
    
    //变长参数,可变参数,相当于数组
    public void addTel(String... str) {
        for(int i=0;i<str.length;i++) {
            tels.add(str[i]);
        }
//        for(String s:str) {
//            
//            tels.add(s);
//        }
    }
}
    Person
    package base;

import java.util.Comparator;

/**
 * 自定义对比器
 * @author ASUS
 *
 */
public class PersonComparator implements Comparator<Person>{

    @Override
    public int compare(Person o1, Person o2) {
        if(o1==null) {
            if(o2==null) {
                return 0;
            }
            else {
                return -1;
                
            }
        }else {
            if(o2==null) {
                return 1;
            }else {
                return o1.getHeight()-o2.getHeight();
            }
        }
    }
    

}
    PersonComparato
    package base;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class ProForDemo {
    public static void main(String[] args) {
        int[] arr= {1,2,3,4};
        //对数组进行for循环
        for(int i:arr) {
            System.out.println(i);
        }
        
        //List Set Map.entrySet|Map.keySet
        List<String> list=new ArrayList<String>();
        list.add("tom");
        list.add("tom");
        list.add("tom");
        list.add("tom");
        //对集合
        for(String s:list) {
            System.out.println(s);
        }
        
        
        
        Person p = new Person(1000);
        p.addTel("132","31111","5353");
    }
}
    ProForDemo
    package base;

import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;

import workhome.Student;

public class TreeMapDemo {

    public static void main(String[] args) {
        TreeMap<String,Student> tm1=new TreeMap<String,Student>();
        tm1.put("tom1",new Student(1,2,3));
        tm1.put("tom1",new Student(1,2,3));
        tm1.put("tom2",new Student(1,2,3));
        tm1.put("tom3",new Student(1,2,3));
        System.out.println(tm1.size());
        
        //迭代
        for(Entry<String,Student> entry : tm1.entrySet()) {
            String k=entry.getKey();
            Student v=entry.getValue();
            System.out.println(k+"-"+v);
        }
        
        //
        TreeMap<Person,String> tm2=new TreeMap<Person,String>(new PersonComparator());
        tm2.put(new Person(100), "tom1");
        tm2.put(new Person(100), "tom2");
        tm2.put(new Person(200), "tom3");
        tm2.put(new Person(300), "tom4");
        System.out.println(tm2.size());
        
        //得到所有key元素
        Set<Person> keys = tm2.keySet();
        Iterator<Person> it=keys.iterator();
        for(;it.hasNext();) {
            Person p = it.next();
            String v=tm2.get(p);
            System.out.println(p+"-"+v);
        }
    }
}
    TreeMap
    package base;

import java.util.TreeSet;


public class TreeSetDemo {
    public static void main(String[] args) {
        TreeSet<Person> ts2=new TreeSet<Person>(new PersonComparator());
        ts2.add(new Person(1));
        ts2.add(new Person(1));
        ts2.add(new Person(2));
        ts2.add(new Person(3));
          System.out.println(ts2.size());
    }
}
    TreeSet
    package workhome;

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

public class MapDemo {
    public static void main(String[] args) {
        Map<Integer, String> map=new HashMap<Integer,String>();
        map.put(100,"tom100");
        map.put(200,"tom200");
        map.put(300,"tom300");
        System.out.println(map.size());
        
        map.remove(300);
        //迭代
        Set<Entry<Integer,String>> entires=map.entrySet();
        for(Entry<Integer,String> entry :entires) {
            Integer key=entry.getKey();
            String value = entry.getValue();
            System.out.println(key+"-"+value);
        }
        
        //
        System.out.println(map.get(100));
        
        //2.通过key迭代
        Set<Integer> keys = map.keySet();
        for(Integer key:keys) {
            System.out.println(key+"=="+map.get(key));
        }
    }
}
    Map
    package workhome;

import java.util.HashMap;
import java.util.Map;

public class MapDemo2 {
    public static void main(String[] args) {
        Map<MyKey,Cat> map=new HashMap<MyKey, Cat>();
        map.put(new MyKey("tom-1"), new Cat("tom-1",12));
        map.put(new MyKey("tom-2"), new Cat("tom-1",13));
        map.put(new MyKey("tom-3"), new Cat("tom-1",14));
        
        Cat c=map.get(new MyKey("tom-1"));
        System.out.println(c);
        
        System.out.println(map.size());
    }        
}
class Cat{
    private String name;
    private int  height;
    
    
    public Cat(String name, int height) {
        super();
        this.name = name;
        this.height = height;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getHeight() {
        return height;
    }
    public void setHeight(int height) {
        this.height = height;
    }
    
}

class MyKey{
    private String name;
    private Integer age;
    
    MyKey(String name){
        super();
        this.name=name;
    }
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    @Override
    public int hashCode() {
        int namehash= name==null ? 0 :name.hashCode();
        int agehash=age==null? 0 : age.intValue();
        return namehash+agehash;
    }
    
    @Override
    public boolean equals(Object obj) {
        MyKey key0=(MyKey)obj;
        return name.equals(key0.name) && age==key0.age;
    }
}
    Map
        package workhome;

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

/**
 * Map嵌套
 * 
 * @author ASUS
 *
 */
public class MapNestedDemo {

    public static void main(String[] args) {
        // 名单集合()
        Map<String, String> names = null;

        // 班级集合
        Map<String, Map<String, String>> classes = null;

        // 年级集合
        Map<String, Map<String, Map<String, String>>> grades = new HashMap<String, Map<String, Map<String, String>>>();
        int no = 0;
        for (int i = 1; i <= 6; i++) {
            // 创建班级集合
            classes = new HashMap<String, Map<String, String>>();
            grades.put(i + "年级", classes);
            for (int j = 1; j <= 2; j++) {
                // 创建名单集合
                names = new HashMap<String, String>();
                classes.put(i + "年级" + j + "班", names);

                for (int k = 1; k <= 5; k++) {
                    names.put("NO" + i + "-" + j + "-" + k, "tom" + (no++));
                }
            }
        }
        //迭代输出
        for(Entry<String,Map<String,Map<String,String>>> entry : grades.entrySet()) {
            //年级
            String key=entry.getKey();
            //班级集合
            Map<String,Map<String,String>> classes1=entry.getValue();
            //先输出年级名称
            System.out.println(key);
            //年级内的每个班
            for(Entry<String,Map<String,String>> e : classes1.entrySet()) {
                //班级名称
                String className=e.getKey();
                //名单集合
                Map<String,String> v=e.getValue();
                System.out.println("	"+className);
                
                for(Entry<String,String> e2 : v.entrySet()) {
                    String stuNo=e2.getKey();
                    String strName=e2.getValue();
                    System.out.println("		"+stuNo+"-"+strName);
                }
                
            }
        }
        
//        //迭代器
//        Iterator<Entry<String,Map<String,Map<String,String>>>> it1=grades.entrySet().iterator();
//        while(it1.hasNext()) {
//            Entry<String,Map<String,Map<String,String>>> e1 =it1.next();
//            String k1=e1.getKey();
//            Map<String,Map<String,String>> v1=e1.getValue();
//            System.out.println(k1);
//            
//            Iterator<Entry<String,Map<String,String>>> it2=v1.entrySet().iterator();
//            while(it2.hasNext()) {
//                Entry<String,Map<String,String>> e2=it2.next();
//                String k2=e2.getKey();
//                Map<String,String> v2= e2.getValue();
//                
//                System.out.println("	"+k2);
//                
//                Iterator<Entry<String,String>> it3=v2.entrySet().iterator();
//                while(it3.hasNext()) {
//                    Entry<String,String> e3=it3.next();
//                    String k3 = e3.getKey();
//                    String v3=e3.getValue();
//                    System.out.println("		"+k3+"-"+v3);
//                }
//            }
//        }
    }
}
    Map
    package workhome;

import java.util.HashSet;
import java.util.Set;

public class SetDemo {
    public static void main(String[] args) {
        //hash：散列，去重
        Set<String> set=new HashSet<String>();
        set.add("tom");
        set.add("tom");
        
    }
}
    Set
    package workhome;

import java.util.HashSet;
import java.util.Set;

public class setDemo2 {
    public static void main(String[] args) {
        Set<Dog2> dogs=new HashSet<Dog2>();
        dogs.add((new Dog2("white")));
        dogs.add(new Dog2("white"));
        System.out.println(dogs.size());
        //System.out.println(dogs.contains(new Dog("white")));
    }
}


class Dog2{
    private String name;
    Dog2(String name){
        super();
        this.name=name;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public int hashCode() {
        return 1;
    }
    @Override
    public boolean equals(Object obj) {
        return true;
    }
}
    set
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  • 原文地址：https://www.cnblogs.com/King-boy/p/11023328.html
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