How can I compare the string with the keys in hash map

Question

I am having difficulties to compare the string (str) with the keys in hashmap. As you can see from the below code, I have multiple keys. I am comparing the str with the keys but I couldn't get the values for that specific key. Please note the map contains coin.

it works only if i directly input the string eg entry.getKey().getKeyOne().toString().contains("coin")

String str = "coin";
for(Map.Entry<Pair, String> entry : map.entrySet()) {
    if(entry.getKey().getKeyOne().toString().contains(str)||
        entry.getKey().getKeyTwo().toString().contains(str)) {
            entry.getValue();
    }
}

public class Pair {
    private String keyOne;
    private String keyTwo;

    Pair(String one,String two) {
        this.keyOne=one;
        this.keyTwo=two;
    }

    public String getKeyOne() {
        return keyOne;
    }

    public String getKeyTwo() {
       return keyTwo;
    }
}

try this it is in android but http://stackoverflow.com/questions/40062224/how-to-get-the-distinct-element-from-mediastore-by-java — Neelay Srivastava, Nov 13 '16 at 09:06
Can you post the toString implementation for KeyOne and KeyTwo if its your own class. If not please add the code for Pair as said earlier by Andrew. — Curious, Nov 13 '16 at 09:15
Can you post how you init your HashMap? It is HashMap? Do you want something like: entry.getKey().contains("coin")? — Alykoff Gali, Nov 13 '16 at 09:47

score 1 · Answer 1 · edited May 23 '17 at 11:53

Advice: As long you are using your own class Pair in a Map you must override equals() and should override hashCode().

~~You example with the string literal works, because "coin" is in the string pool and all references the same String.~~

Runs here:

public class Pair {

    private String keyOne;
    private String keyTwo;

    Pair(String one, String two) {
        this.keyOne = one;
        this.keyTwo = two;

    }

    public String getKeyOne() {
        return keyOne;
    }

    public String getKeyTwo() {
        return keyTwo;

    }

    public static void main(String[] args) {
        Map<Pair, String> map = new HashMap();
        map.put(new Pair("coin", "5"), "U");
        map.put(new Pair("bill", "100"), "H");
        map.put(new Pair("10", "5coin"), "T");

        String str = new String("coin");
        for (Map.Entry<Pair, String> entry : map.entrySet()) {
            if (entry.getKey().getKeyOne().toString().contains(str)
                    || entry.getKey().getKeyTwo().toString().contains(str)) {
                System.err.println(entry.getValue());
            }
        }
    }
}

Can you give me an example please? – elyon Nov 13 '16 at 09:59 — elyon, Nov 13 '16 at 09:59

Shalin Patel · Answer 2 · 2016-11-13T10:46:51.797

Here is simple sample code for you If you want it for one Hashmap only

public void findInkeys(String findkey){
    HashMap<String, Object> map=new HashMap<>();

    //Place your content of MAp Here
    //Start

    //end
    //or you can place your content anywhere else but make sure is is initialized before this


    Set<String> keys=map.keySet();
    boolean isInKeys=false;
    for (String k : keys)
    {
        if(k.equals(findkey))
        {
            isInKeys=true;
        }
    }
    System.out.println(isInKeys);
}

if you want it for any hashmap

public void findInkeys(HashMap<String,Object> map,String findkey){

    Set<String> keys=map.keySet();
    boolean isInKeys=false;
    for (String k : keys)
    {
        if(k.equals(findkey))
        {
            isInKeys=true;
        }
    }
    System.out.println(isInKeys);
}

if you have multiple Keys to compare then go with below code

public void findInkeys(HashMap<String, String> map,ArrayList<String> keyList){
    Set<String> keys=map.keySet();
    boolean isInKeys=false;
    for (String k : keys)
    {
        if(keyList.contains(k))
        {
            isInKeys=true;
        }
    }
    System.out.println(isInKeys);
}

How can I compare the string with the keys in hash map

2 Answers2