How to get an object from a HashMap in Java

Question

I'm trying to get the speed of a test object from a HashMap when specifying a key, but I'm not quite sure how to do this. I tried this way, but its wrong:

hash.values().getSpeed(); 

Any help? Thanks

 class Test { private String id; private String name; private int speed; public Test(String id, String name, int speed) { this.id = id; this.name = name; this.speed = speed; } public String getId() { return id; } public String getName() { return name; } public int getSpeed() { return speed; } } public class Driver { public static void main(String[] args) { HashMap<String, Test> hash = new HashMap<String, Test>(); Test c1; Test c2; c1 = new Test("Z", "B", 4); c2 = new Test("Y", "D", 7); hash.put("A", c1); hash.put("C", c2); } } 

Answer 1

 Test c1; Test c2; c1 = new Test("Z", "B", 4); c2 = new Test("Y", "D", 7); hash.put("A", c1); hash.put("C", c2); Test getC1 = (Test)hash.get("A"); Test getC2 = (Test)hash.get("C"); 

Answer 2

The values ​​() method returns a collection of values ​​contained in a HashMap object. You can use for loop to move the collection of values.

 for(Test t:hash.values()) { System.out.println(t.getSpeed()); } 

Answer 3

There is a method in the map interface with the following signature type + return:

 E get(T key); 

Answer 4

hash.get("A") or more generally: hash.get(key) , where key was the first argument to the hash.put(key, value) call.

Answer 5

get is the opposite of put . So just hash.get("C"); will give you c1 etc.

I suggest you learn the Javadoc from classes that you use more carefully before publishing.

Answer 6

 public class Driver { public static void main(String[] args) { HashMap<String, Test> hash = new HashMap<String, Test>(); Test c1; Test c2; c1 = new Test("A", "Maruthi", 4); c2 = new Test("B", "Toyota", 7); hash.put("A", c1); hash.put("B", c2); for(Test t:hash.values()) { System.out.println(t.getSpeed() + " " + t.getId() + " " + t.getName()); } } }