Converting Hashmap into single string array in java

Question

I'm working on a program for class and have been beating my head for days on this. I have to find the number of occurrences in a string. I've been able to get the results into a HashMap. However, I need to be able to convert it to a single string array so that I can assertTrue and test it. Here's what I have so far. Any suggestions would be greatly appreciated. Thanks.

public static void main(String[] args) 
    {
        String input = "xyz 456 123 123 123 123 123 123 xy 98 98 xy xyz abc abc 456 456 456  98 xy"; //String to be tested
        String[] str = input.split(" "); // String put into an array

        Map<String, Integer> occurrences = new HashMap<String, Integer>();
        Integer oldValue = 0;

        for (String value : str)
        {
            oldValue = occurrences.get(value);
            if (oldValue == null)
            {
                occurrences.put(value, 1); 
            } else
            {
                occurrences.put(value, oldValue + 1);
            }
        }
        occurrences.remove("");

}

The target string array:

[xy, 3, 123, 6, abc, 2, 456, 4, xyz, 2, 98, 3]

How do u want to convert the hashmap into string. It is not clear. — Umair Farooq
– Umair Farooq, Commented Aug 13, 2016 at 13:59
Is this question fully answered? Then please accept it as an answer or post a follow up question. Thanks. — Frederic Klein
– Frederic Klein, Commented Aug 14, 2016 at 12:15

Frederic Klein · Accepted Answer · 2016-08-13 17:02:33Z

3

Is the question, how you can read the key-value-pairs from your hashmap?

Then the following example demonstrates some simple readings:

for(String entry : occurrences.keySet()) {
    Integer value = occurrences.get(entry);         
    System.out.println(entry + ":" + value);
}

Output:

xy:3
123:6
abc:2
456:4
xyz:2
98:3

Update:

to get a string array [key, value, key, value, ...] use the following code:

ArrayList<String> strings = new ArrayList<>();

for(String entry : occurrences.keySet()) {
    strings.add(entry);
    strings.add(""+occurrences.get(entry));
}

String[] asArray = strings.toArray(new String[strings.size()]);

Or without ArrayList:

String[] asArray = new String[occurrences.size()*2];
int index = 0;

for(String entry : occurrences.keySet()) {
    asArray[index++]=entry;
    asArray[index++]=""+occurrences.get(entry);
}

edited Aug 13, 2016 at 17:02

answered Aug 13, 2016 at 14:12

Frederic Klein

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4 Comments

Jm Sween Over a year ago

Not exactly. I need to test a string that results in an array that calculates the number of occurrences a word appears in a string. I was able to get the expected result in a hash map but now I need to convert it to a string array so that I can test it against the actual result.

Frederic Klein Over a year ago

Can you give us "the actual result", so we can help you? Otherwise we have to guess, what format the strings in the string[] should have. Since you have a string (the keys) and the Integers (the values), you have to combine them in some format if you intend to store them in a single array of strings.

Jm Sween Over a year ago

Oh sure. Sorry about that. In this case the result should be:

Jm Sween Over a year ago

In the form of an array: [xy, 3, 123, 6, abc, 2, 456, 4, xyz, 2, 98, 3]

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