How to verify HashMap containsValue with partial String

Question

I was working on a program to validate that a map contains some set of values or not. Map API is having one method called as map.containsValue(string). But, this method verify complete String as value.

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

public class TestMap {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Map<Integer, String> map = new HashMap<Integer, String>();

        map.put(6, "P_T");
        map.put(7, "P_Q_T");
        map.put(8, "T");
        map.put(9, "A");
        map.put(10, "B");
        map.put(11, "P_A");
        map.put(1, "P_1");
        map.put(2, "Q");
        map.put(3, "P_Q");
        map.put(4, "Q_T");
        map.put(5, "T");

        System.out.println("Map is = "+map);

        System.out.println("Result is = " + map.containsValue("P"));
    }
}

Above program will return output as :

Map is = {1=P_1, 2=Q, 3=P_Q, 4=Q_T, 5=T, 6=P_T, 7=P_Q_T, 8=T, 9=A, 10=B, 11=P_A}
Result is = false

My requirement is that Result should be true as, Map contains keys 1, 3, 6, 7, 11, which contains char P as value.

I have a solution, that i could use loop to verify each value and then find indexOf each value for P char.

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class TestMap {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Map<Integer, String> map = new HashMap<Integer, String>();

        map.put(6, "P_T");
        map.put(7, "P_Q_T");
        map.put(8, "T");
        map.put(9, "A");
        map.put(10, "B");
        map.put(11, "P_A");
        map.put(1, "P_1");
        map.put(2, "Q");
        map.put(3, "P_Q");
        map.put(4, "Q_T");
        map.put(5, "T");

        System.out.println("Map is = " + map);

        System.out.println("Result is = " + map.containsValue("P"));

        System.out.println("Result from loop is = " + verifyMap(map));

    }

    private static boolean verifyMap(Map<Integer, String> map) {
        // TODO Auto-generated method stub
        Set<Integer> set = map.keySet();
        Iterator<Integer> itr = set.iterator();
        while (itr.hasNext()) {
            Integer integer = (Integer) itr.next();
            String str = map.get(integer);
            if (str.indexOf("P") >= 0)
                return true;
        }
        return false;
    }
}

I have evaluated string with indexOf method instead of contains, which is marginally faster .

See this question

This return the desired result as:

Result from loop is = true

But, I just want to know, is there any other way to verify same?

Answer 1

You can write your method with less code using Java 8 Streams :

private static boolean verifyMap(Map<Integer, String> map) {
    return map.values().stream().anyMatch(str->str.indexOf("P") >= 0);
}

Even in Java 7 your method can be shorter :

private static boolean verifyMap(Map<Integer, String> map) {
    for (String str : map.values()) {
        if (str.indexOf("P") >= 0)
            return true;
    }
    return false;
}