Parsing a String in java

Question

I get following strings from a server, only separated by spaces. (Line breaks are just due to readability, "XX is a placeholder and can vary in length. also the length of the things in square brackets can vary in length.

String 1:

status:ok [XXX][a=XXX b=XXX c=XXX d=XXX e=0 f=XXX g=XXX h=XXX i=XXX j=XXX 
k=XXX l=XXX m=XXX n=[[XXX][XXX]] p=[[XXX][XXX][XXX][XXX][XXX][XXX][XXX]]]
end:end

String 2:

status:ok [XXX][a=XXX b=XXX  c=XXX d=XXX d2=XXX e=XXX  f=XXX g=XXX h=XXX i=XXX j=XXX 
k=XXX l=XXX m=XXX n=[[XXX][XXX]] p=[[XXX][XXX][XXX][XXX][XXX][XXX][XXX]]]
end:end

All parts in square brackets "[]" can contain more or less of "[]"-elements and words inside a inner "[]" can vary in length. I need those a,b,c,d,e etc. in a HashMap, but before i can do that i need to parse it somehow.

How can i parse this string efficiently in Java?

I have searched and found lots of websites and threads where people suggested something called "key value parsing" apart from "Regex parsing", but unfortunately information on "key value parsing" is sparse.

EDIT: In the end I want to store those values in a Hashmap like this:

HashMap<String,Object> myHashMap = new HashMap();
myHashMap.put(a, XXX);
....
myHashMap.put(p,array-of-all-[XXX]);

i need to parse it somehow. -> How exactly is that somehow? — Rohit Jain
– Rohit Jain, Commented Nov 24, 2012 at 16:41
with "All parts in square brackets "[]" can contain more or less of "[]"-elements" you mean that anything within square brackets is optional? — holgero
– holgero, Commented Nov 24, 2012 at 16:48
Did you need that n, and p, too, or only the a - m in your example (m and p are nested) — AlexWien
– AlexWien, Commented Nov 24, 2012 at 16:51

someone · Accepted Answer · 2012-11-24 17:58:48Z

2

You could simply do this and it will print your a,b,c ..

  String s ="status:ok [XXX][a=XXX b=XXX c=XXX d=XXX e=0 f=XXX g=XXX h=XXX i=XXX j=XXX k=XXX l=XXX m=XXX n=[[XXX][XXX]] p=[[XXX][XXX][XXX][XXX][XXX][XXX][XXX]]] end:end".replaceAll("end:end", "");

    String [] ss  = s.split("=");
    HashMap<Character,Object> myHashMap = new HashMap();
    try{
    for(int i=0;i<ss.length;i++){

        myHashMap.put(ss[i].charAt(ss[i].length()-1), ss[i+1].substring(0, ss[i+1].length()-1).trim());

    }

    }catch(Exception e){
        // do nothing
    }
      System.out.println(myHashMap);
    }

edited Nov 24, 2012 at 17:58

answered Nov 24, 2012 at 16:52

someone

6,5728 gold badges43 silver badges63 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

AlexWien Over a year ago

does not work for n and p, where he wants an array of XXX instead of an string

vels4j · Accepted Answer · 2012-11-24 16:50:48Z

0

Will this help

String str = "status:ok [XXX][a=XXX b=XXX c=XXX d=XXX e=0 f=XXX g=XXX h=XXX i=XXX j=XXX k=XXX l=XXX m=XXX n=[[XXX][XXX]] p=[[XXX][XXX][XXX][XXX][XXX][XXX][XXX]]] end:end";
String[] splitStrA = str.split(" ");         
HashMap<String,String> map = new HashMap() ;
for (String splitStr : splitStrA) {
    String[] splitStr1 = splitStr.split("=");
    if (splitStr1.length == 2) {
        map.put(splitStr1[0], splitStr1[1]);
    }
}
System.out.println(map);

answered Nov 24, 2012 at 16:50

vels4j

11.3k5 gold badges44 silver badges67 bronze badges

1 Comment

AlexWien Over a year ago

does not work for n and p, where he wants an array instead of an string

Has QUIT--Anony-Mousse · Accepted Answer · 2012-11-24 16:52:58Z

Instead of using regular expressions, how about using a classic string tokenizer?

These days, everybody tries to smash everything with regexps. That made a lot of sense in Perl, as regexp were a very shorthand syntax there. But for Java, regexps are a bit clumsy.

However, Java brings along a number of useful classes, for example StringTokenizer. Some people consider it discouraged, but in many situations it is very useful.

And of course there are various packages that help with parsing file formats.

CUP for example is a parser generator used by the Weka machine learning toolkit.

JFlex is likely inspired by the classic C "flex" parser generator (and Yacc, Bison etc.)

A good parser will be able to e.g. parse nested expressions. It will know how to interpret expressions such as a=[[1,2],[3,4]] even when they are nested deeply. Regular expressions cannot do that.

There is nothing wrong with regular expressions. But they are designed for matching, not such much for parsing.

AlexWien · Accepted Answer · 2012-11-24 17:00:43Z

Its not Regex-Parsing, but a bit of key value parsing, but mainly it is general parsing.
You should study that topic.

The problem in your String is that an expression [] can contain other expressions (nested [[]]).
This is nothing which can be solved in 3 lines.
Try to search for explanation how to parse expression.
Further you need to understand what a "Grammar" is. Then write down the grammar of that expression in the string,
then half of the work is done, because you can implement the parse more or less strictly following the grammar.

Another solution: use one of the answers above that does not work for n and p (arrays). And in an second step you parse the expresssion [[XXX][XXX][XXX][XXX][XXX][XXX]], which is not so diffult; (you can use String.split("]") and go back in the string till you find the "[").

Collectives™ on Stack Overflow

Parsing a String in java

4 Answers 4

1 Comment

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related