Java Map

public class Person {

    public static void main(String[] args) {

        Map<Integer, String> map = new HashMap<Integer, String>();

        map.put(12, "aaa");
        map.put(22, "df");
        map.put(72, "awe");
        map.put(32, "34");
        map.put(52, "fhd");
        
//        Set<Integer> mapSet = map.keySet();      //获取包含所有key的Set容器
//        Iterator<Integer> it = mapSet.iterator();
//        while(it.hasNext())
//        {
//            Integer x = it.next();
//            System.out.println(x + " : " + map.get(x));
//        }


//        Collection<String> coll = map.values();    //获取包含所有value的Collection容器
//        Iterator<String> it = coll.iterator();
//        while(it.hasNext())
//        {
//            System.out.println(it.next());
//        }
        
        Set<Map.Entry<Integer, String>> mapEntries = map.entrySet();
        Iterator<Map.Entry<Integer, String>> it = mapEntries.iterator();
        while(it.hasNext())
        {
            Map.Entry<Integer, String> mEntry = it.next();
            System.out.println(mEntry.getKey() + " : " + mEntry.getValue());
        }
        

    }
}

 

class Car 
{
    private String name;
    private int number;
    private double weight;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getNumber() {
        return number;
    }
    public void setNumber(int number) {
        this.number = number;
    }
    public double getWeight() {
        return weight;
    }
    public void setWeight(double weight) {
        this.weight = weight;
    }
    
    
    public Car(String name, int number, double weight) {
        this.name = name;
        this.number = number;
        this.weight = weight;
    }
    @Override                                                
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        result = prime * result + number;
        long temp;
        temp = Double.doubleToLongBits(weight);
        result = prime * result + (int) (temp ^ (temp >>> 32));
        return result;
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Car other = (Car) obj;
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
        if (number != other.number)
            return false;
        if (Double.doubleToLongBits(weight) != Double
                .doubleToLongBits(other.weight))
            return false;
        return true;
    }
    
    
}


public class Person {

    public static void main(String[] args) {

        Map<Car, String> map = new Hashtable<Car, String>();
        
        map.put(new Car("aaa", 111,1.02), "abc");
        map.put(new Car("bbb", 222,1.02), "bcd");
        map.put(new Car("ccc", 333,1.02), "cde");
        map.put(new Car("aaa", 111,1.02), "qqq");
        map.put(new Car("bbb", 234,1.02), "bcd");

        Car car = new Car("zzz", 999,1.01);
        map.put(car, "iii");

        Set<Map.Entry<Car, String>> mapEntries = map.entrySet();
        Iterator<Map.Entry<Car, String>> it = mapEntries.iterator();
        while(it.hasNext())
        {
            Map.Entry<Car, String> mEntry = it.next();
            System.out.println(mEntry.getKey().getName() + " : "  + mEntry.getKey().getNumber() + " :" + mEntry.getValue());
        }
        
        System.out.println(map.containsKey(new Car("aaa", 111,1.02)));
        System.out.println(map.containsKey(car));
    }
}

 

 

class Car
{
    private String name;
    private int number;
    private double weight;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getNumber() {
        return number;
    }
    public void setNumber(int number) {
        this.number = number;
    }
    public double getWeight() {
        return weight;
    }
    public void setWeight(double weight) {
        this.weight = weight;
    }
    
    
    public Car(String name, int number, double weight) {
        this.name = name;
        this.number = number;
        this.weight = weight;
    }

}


public class Person {

    public static void main(String[] args) {

        Map<Car, String> map = new TreeMap<Car, String>();
        
        map.put(new Car("aaa", 111,1.02), "abc");
        map.put(new Car("bbb", 222,1.02), "bcd");
        map.put(new Car("ccc", 333,1.02), "cde");
        map.put(new Car("aaa", 111,1.02), "qqq");
        map.put(new Car("bbb", 234,1.02), "bcd");


        Set<Map.Entry<Car, String>> mapEntries = map.entrySet();
        Iterator<Map.Entry<Car, String>> it = mapEntries.iterator();
        while(it.hasNext())
        {
            Map.Entry<Car, String> mEntry = it.next();
            System.out.println(mEntry.getKey().getName() + " : "  + mEntry.getKey().getNumber() + " :" + mEntry.getValue());
        }
    
    }
}

class Car implements Comparable
{
    private String name;
    private int number;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getNumber() {
        return number;
    }
    public void setNumber(int number) {
        this.number = number;
    }
    
    public Car(String name, int number) {
        this.name = name;
        this.number = number;
    }
    
    @Override
    public int compareTo(Object o) {
        if(!(o instanceof Car))
        {
            throw new ClassCastException("类型错误!");
        }
        Car c = (Car)o;
        int temp = this.getName().compareTo(c.getName());
        
        return temp == 0 ? this.getNumber() - c.getNumber() : temp;
    }
    
}


public class Person {

    public static void main(String[] args) {

           //对于TreeMap容器，只需要实现对象中的比较方法compareTo()，其内部是通过二叉树实现的，
           //当查找元素时，不会去调用hashCode()和equals(Object obj)方法。
        Map<Car, String> map = new TreeMap<Car, String>();
        
        map.put(new Car("aaa", 111), "abc");
        map.put(new Car("bbb", 222), "bcd");
        map.put(new Car("ccc", 333), "cde");
        map.put(new Car("aaa", 111), "qqq");
        map.put(new Car("bbb", 234), "bcd");


        Set<Map.Entry<Car, String>> mapEntries = map.entrySet();
        Iterator<Map.Entry<Car, String>> it = mapEntries.iterator();
        while(it.hasNext())
        {
            Map.Entry<Car, String> mEntry = it.next();
            System.out.println(mEntry.getKey().getName() + " : "  + mEntry.getKey().getNumber() + " :" + mEntry.getValue());
        }
        
        System.out.println(map.containsKey(new Car("aaa", 111)));

    }
}