new HashMap<K, V>()
/**
*Output:
D: 99.22
A: 3434.34
C: 1378.0
B: 123.22
E: -19.08
B's new balance: 1123.22
*/
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class MainClass {
public static void main(String args[]) {
HashMap<String, Double> hm = new HashMap<String, Double>();
hm.put("A", new Double(3434.34));
hm.put("B", new Double(123.22));
hm.put("C", new Double(1378.00));
hm.put("D", new Double(99.22));
hm.put("E", new Double(-19.08));
Set<Map.Entry<String, Double>> set = hm.entrySet();
for (Map.Entry<String, Double> me : set) {
System.out.print(me.getKey() + ": ");
System.out.println(me.getValue());
}
System.out.println();
double balance = hm.get("B");
hm.put("B", balance + 1000);
System.out.println("B's new balance: " + hm.get("B"));
}
}
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HashMap:
- HashMap Class
- new HashMap<K, V>()
- clear() removes all elements in a HashMap
- clone() creates a copy of the HashMap
- containsKey(Object key) checks to see if the HashMap has that key
- containsValue(Object value) checks if the HashMap has that value
- entrySet() returns the key-value pair as a set
- keySet() returns the key set
- get(E o) returns the value by the key
- put(E o, E o1) add value and key to a HashMap
- putAll(Map<?, ?> m) adds another map
- remove(Object key) deletes an entry by a key
- size() returns the size of a HashMap
- values() returns the value of the