create map java

1Map<String, String> map = new HashMap<>();
2
3for(Entry<String, String> entry:map.entrySet()) {
4  System.out.println("key: "+entry.getKey()+" value: "+entry.getValue());
5}

1Map<String, Integer> map = new HashMap<>();

1Map <Integer, Point2D.Double> hm = new HashMap<Integer, Point2D>();
2hm.put(1, new Point2D.Double(50, 50));

1Map< String,Integer> hm =  
2                        new HashMap< String,Integer>(); 
3       hm.put("a", new Integer(100)); 
4       hm.put("b", new Integer(200)); 
5       hm.put("c", new Integer(300)); 
6       hm.put("d", new Integer(400)); 

1/**
2 * @author Jack Waller <jw309@st-andrews.ac.uk>
3 * @version 1.1
4 * @since 2020-03-28
5 * A implementation of Map.Entry.
6 */
7public final class Pair<K, V> implements Map.Entry<K, V> {
8
9    //variables
10    private final K key;
11    private V value;
12
13    //constructor
14    public Pair(K key, V value) {
15        this.key = key;
16        this.value = value;
17    }
18
19    //methods
20
21    /**
22     * Returns the key.
23     * @return K
24     */
25    @Override
26    public K getKey() {
27        return key;
28    }
29
30    /**
31     * Returns the value.
32     * @return V
33     */
34    @Override
35    public V getValue() {
36        return value;
37    }
38
39    /**
40     * Sets the value, returns the old value
41     * @param v value to set
42     * @return V
43     */
44    @Override
45    public V setValue(V v) {
46        V old = this.value;
47        this.value = v;
48        return old;
49    }
50}