Can not for each in HashMap

Question

I tried to use for each loop to iterate through HashMap keys but it doesn't compile.

Here is my code:

import java.util.Map;
import java.util.HashMap;

public class theseeker{
    public static void main(String[] args){

        Map blue = new HashMap<Character,Integer>();
        for(char c = 'a';c <= 'z';c++)
            blue.put(new Character(c),new Integer((int)c));

        for(Character c : blue.keySet())
            System.out.println(c);


    }


}

I get this error:

 Object cannot be converted to Character
        for(Character c : blue.keySet())
                                     ^

Does it happen beacuse of using interface?

score 2 · Accepted Answer · answered Dec 12 '18 at 10:55

2

You're map defaults to objects set it's casts

Map<Character, Integer> blue = new HashMap<>();

After cleaning up your code it should look like the following

public static void main(String[] args) {
    Map<Character, Integer> blue = new HashMap<>();

    for (char c = 'a'; c <= 'z'; c++) {
        blue.put(c, (int) c);
    }

    for (Character c : blue.keySet()) {
        System.out.println(c);
    }
}

answered Dec 12 '18 at 10:55

SamHoque

2,978
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Thank you it workes. So when I use interface Map I have to specify the Base_type of key and value. Am ı right? – Ömer Faruk Genç Dec 12 '18 at 11:28
No you don't it is already specified `` – SamHoque Dec 12 '18 at 11:29
Okay I got it now. Default type of Interface Map is – Ömer Faruk Genç Dec 12 '18 at 13:52

Can not for each in HashMap

1 Answers1