Parse a string with variable key value pairs

Question

I have a string like this:

*********** name: NOTINSTATE timestamp: 2015-09-16T12:33:01.253Z 
MyKeyValue1 = myData MyKeyValue2 = 0.0 based on filter: no Filter
********************************

In this String i have the KeyValuePairs:

"name" NOTINSTATE
"timestamp" 2015-09-16T12:33:01.253Z
"MyKeyValue1" myData
"MyKeyValue2" 0.0
"based on filter" no Filter

I was thinking about something like Freemarker in reverse way but i don't think that Freemarker others this functionality.

I know i could do it on a dirty way and work with pattern and split the String but there must be a better way to do this.

Any suggestions or frameworks which would be useful? My searchString itself will not be changed in the future. It will be always the same.

The values are obviously variable, but are the keys variable? All of them? — Andreas
– Andreas, Commented Sep 17, 2015 at 16:19
I was think about using some regex where i can say what is between two patterns to get my value. But i would have to do it for very value. This would be the dirty way. — nik the lion
– nik the lion, Commented Sep 17, 2015 at 16:24

Andreas · Accepted Answer · 2015-09-17 16:47:03Z

2

A regular expression is your friend:

String input = "*********** name: NOTINSTATE timestamp: 2015-09-16T12:33:01.253Z\n" +
               "MyKeyValue1 = myData MyKeyValue2 = 0.0 based on filter: no Filter\n" +
               "********************************";
String regex = "\\*+\\s+" +
               "(name):\\s+(.*?)\\s+" +
               "(timestamp):\\s+(.*?)\\s*[\r\n]+" +
               "(MyKeyValue1)\\s+=\\s+([^=]*)\\s+" +
               "(MyKeyValue2)\\s+=\\s+([^=]*)\\s+" +
               "(based on filter):\\s+(.*?)\\s*[\r\n]+" +
               "\\*+";
Matcher m = Pattern.compile(regex).matcher(input);
if (m.matches()) {
    Map<String, String> pairs = new LinkedHashMap<>();
    for (int i = 1; i <= 10; i += 2)
        pairs.put(m.group(i), m.group(i + 1));

    // print for testing
    for (Entry<String, String> entry : pairs.entrySet())
        System.out.printf("\"%s\" %s%n", entry.getKey(), entry.getValue());
}

Output is exactly what you showed:

"name" NOTINSTATE
"timestamp" 2015-09-16T12:33:01.253Z
"MyKeyValue1" myData
"MyKeyValue2" 0.0
"based on filter" no Filter

Update

The above regex is lenient on spaces, but strict on key names. You could go strict on spaces and lenient on key names, or any other combination:

String regex = "\\*+ " +
               "(\\w+): (.+?) " +
               "(\\w+): (.+?)[\r\n]+" +
               "(\\w+) = ([^=]+?) " +
               "(\\w+) = ([^=]+?) " +
               "([^:]+): (.+?)[\r\n]+" +
               "\\*+";

edited Sep 17, 2015 at 16:47

answered Sep 17, 2015 at 16:33

Andreas

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1 Comment

nik the lion Over a year ago

I was thinking about regex but not a regex string to get all the value's. I have to do more with regex.

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