nick nick - 1 month ago 14
Java Question

How can I iterate over the elements in Hashmap?

I want to make a Java game. At first the program asks for the number of the players; after that, it asks for their names. I put their names in a

HashMap
with an ID and their score. At the end of the game I count the score and I want to put it in the
HashMap
(the specific score for the specific name). Does anyone know how to do this? This is my code:

Player:

public class Player {

public Player() {
}

public void setScore(int score) {
this.score = score;
}

public void setName(String name) {
this.name = name;
}

private String name;
private int score;

public Player(String name, int score) {
this.name = name;
this.score = score;
}
public String getName() {
return name;
}

@Override
public String toString() {
return "Player{" + "name=" + name + "score=" + score + '}';
}

public int getScore() {
return score;
}


main:

Scanner scanner = new Scanner(System.in);
HashMap<Integer,Player> name= new HashMap<Integer,Player>();

System.out.printf("Give the number of the players ");
int number_of_players = scanner.nextInt();


for(int k=1;k<=number_of_players;k++)
{


System.out.printf("Give the name of player %d: ",k);
name_of_players= scanner.nextLine();
name.put(k, new Player(name_of_players,0));//k=id and 0=score

}


//This for finally returns the score and
for(int k=1;k<=number_of_players;k++)
{
Player name1 = name.get(k);
System.out.print("Name of player in this round:"+name1.getName());
..............
.............
int score=p.getScore();
name.put(k,new Player(name1.getName(),scr));//I think here is the problem

for(int n=1;n<=number_of_players;n++)//prints all the players with their score
{

System.out.print("The player"+name1.getName()+" has "+name1.getScore()+"points");

}


Does anyone know how can I finally print for example:

"The player Nick has 10 points.
The player Mary has 0 points."


Update:

I did this in main(as Jigar Joshi suggest)

name.put(k,new Player(name1.getName(),scr));
Set<Map.Entry<Integer, Player>> set = name.entrySet();

for (Map.Entry<Integer, Player> me : set)
{
System.out.println("Score :"+me.getValue().getScore() +" Name:"+me.getValue().getName());

}


and it prints "Score :0 Name : a Score :4 Name : a" when i put two names of players "a" and "b".I think the problem is here

name.put(k,new Player(name1.getName(),scr));


How can I put the names in "names_of_players" of my previous
for
?

Answer

Need Key & Value in Iteration

Use entrySet() to iterate through Map and need to access value and key:

Map<String, Person> hm = new HashMap<String, Person>();

hm.put("A", new Person("p1"));
hm.put("B", new Person("p2"));
hm.put("C", new Person("p3"));
hm.put("D", new Person("p4"));
hm.put("E", new Person("p5"));

Set<Map.Entry<String, Person>> set = hm.entrySet();

for (Map.Entry<String, Person> me : set) {
  System.out.println("Key :"+me.getKey() +" Name : "+ me.getValue().getName()+"Age :"+me.getValue().getAge());

}

Need Key in Iteration

If you want just to iterate over keys of map you can use keySet()

for(String key: map.keySet()) {
     Person value = map.get(key); 
}

Need Value in Iteration

If you just want to iterate over values of map you can use values()

for(Person person: map.values()) {

}