Replace String values with value in Hash Map

Question

I'm new to Java Programming. I have created a hash map that contains my Key Value pairs to utilize in replacing user input with the value corresponding to the respective key.

i.e.

        HashMap<String,String> questionKey = new HashMap<>();             

         for (item : itemSet()) {
             questionKey.put(String.valueOf(item.getOrder()+1), item.getKey());                                
         }                    
        String list = commandObject.getObjectItem().getList();

        if (list.contains("q")){                
            list.replaceAll("q01", questionKey.get("1"));               
            commandObject.getObjectItem().setList(list);
        }

I am using this in a formula evaluation

Note: Users are given a certain formula specific way of entry (value1 + value2 + value3)

I'm taking that (value1 value2 value3) and converting it to (value1key value2key value3key)

Update:

The Question as I understand it better now was meant to be to help better understand how to utilize a hashmap in order to evaluate user input. The more clear question would be

What would be the best approach to evaluate an expression i.e.

User Input = "var1 + var2"

Expected Value: valueOf(var1) + valueOf(var2)

?

Your code won't even remotely compile. Not even sure what you're trying to achieve is understandable. Please provide compilable code, stack trace if any, and a clearer scope. — Mena
– Mena, Commented Sep 3, 2013 at 20:37
@SJuan76 To Clarify this is a Spring Application and I am attempting to take the user's input and replace with the corresponding keyValue when the form is submitted to the database as a reference for later formula calculation. — DD84
– DD84, Commented Sep 3, 2013 at 20:43
@Mena I can post the pseudo code with a few more details if that would help. — DD84
– DD84, Commented Sep 3, 2013 at 20:44

Alfredo Osorio · Accepted Answer · 2014-09-15 14:14:10Z

29

@Test
public void testSomething() {
    String str = "Hello ${myKey1}, welcome to Stack Overflow. Have a nice ${myKey2}";
    Map<String, String> map = new HashMap<String, String>();
    map.put("myKey1", "DD84");
    map.put("myKey2", "day");
    for (Map.Entry<String, String> entry : map.entrySet()) {
        str = str.replace("${" + entry.getKey() + "}", entry.getValue());
    }
    System.out.println(str);        
}

Output:

Hello DD84, welcome to Stack Overflow. Have a nice day

For something more complex I'd rather use OGNL.

edited Sep 15, 2014 at 14:14

answered Sep 3, 2013 at 20:43

Alfredo Osorio

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2 Comments

DD84 Over a year ago

I dread asking questions in forums or on this site because all I receive is ridicule even as a beginner. I'm trying to learn just as anyone else. @AlfredoOsorio thanks for you answer but do to it's sarcastic nature I choose not to accept it as my answer.

JNL Over a year ago

@DD84 Just a friendly advice, the important thing here is to learn. I do not think Sarcasm should take effect here in any way. Just take it for now and then maybe after some months answer some of Alfredo's questions. :)

David Barda · Accepted Answer · 2019-01-26 08:40:56Z

3

Java 8 reveals a functional approach which is given in this post.
You are just creating a new function for each word in your map and chain them together. e.g:

public static void main(String[] args) {
    Map<String, String> dictionary = new HashMap<>();
    String stringToTranslate = "key1 key2"
    dictionary.put("key1", "value1");
    dictionary.put("key2", "value2");
    String translation = dictionary.entrySet().stream()
        .map(entryToReplace -> (Function<String, String>) s -> s.replace(entryToReplace.getKey(), 
             s.replace(entryToReplace.getValue())
        .reduce(Function.identity(), Function::andThen)
        .apply(stringToTranslate);
}

edited Jan 26, 2019 at 8:40

answered Jun 24, 2018 at 11:11

David Barda

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2 Comments

Roland Illig Over a year ago

It's more efficient to iterate over the string than over the map. The string might be short, and the map may contain millions of entries.

user9171899 Over a year ago

Oh compiled error. I think you should fix line

.map(entryToReplace -> (Function<String, String>) s -> s.replace(entryToReplace.getKey(),               s.replace(entryToReplace.getValue())

to .map(entryToReplace -> (Function<String, String>) s -> s.replace(entryToReplace.getKey(), entryToReplace.getValue()))

cjsimon · Accepted Answer · 2016-04-23 23:08:02Z

2

import java.util.HashMap;

class Program
{
    public static void main(String[] args)
    {
        String pattern = "Q01 + Q02";
        String result = "";

        HashMap<String, String> vals = new HashMap<>();

        vals.put("Q01", "123");
        vals.put("Q02", "123");

        for(HashMap.Entry<String, String> val : vals.entrySet())
        {
            result = pattern.replace(val.getKey(), val.getValue());
            pattern = result;
        }

        System.out.println(result);

    }
}

edited Apr 23, 2016 at 23:08

cjsimon

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answered Sep 4, 2013 at 17:11

DD84

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2 Comments

Cristiam Mercado Over a year ago

It's more efficient to use StringBuilder in result variable. Remember String is immutable.

Roland Illig Over a year ago

It's more efficient to iterate over the string than over the map. The string might be short, and the map may contain millions of entries.

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