How to add a string after a particular character in another string in java?

Question

I have a file with a big list of strings which is of the form

key1=value1  
key2=value2  
...

I need to add a string for eg. (Long) after every equal sign. And create a new file with these new strings:

key1=(Long)value1.
key2=(Long)value2.
...

How to implement this with a java program?

Search for = and replace it by =(Long). Look in the methods of class String for usefule methods that you can use for this. — Jesper
– Jesper, Commented Feb 26, 2013 at 9:05
Or you could do this in one line with awk. awk -F= '{ print $1"=(Long)"$2 }' bigfile — squiguy
– squiguy, Commented Feb 26, 2013 at 9:07
Might I suggest using the Apache StringUtils replace over the default java replace if you can? — Quetzalcoatl
– Quetzalcoatl, Commented Feb 26, 2013 at 9:20

Alberto Segura · Accepted Answer · 2013-02-26 09:06:34Z

5

BufferedReader b = new BufferedReader(new FileInputStrem(file));

while(b.readLine() != null) {
     System.out.println(line.replace("=", "=(Long)"));
}

b.close();

answered Feb 26, 2013 at 9:06

Alberto Segura

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Comments

Kai · Accepted Answer · 2013-02-26 09:12:41Z

2

"key1=value1".replace("=", "=(Long)");

respectively:

"key1=value1".replace("=", "=" + String.valueOf(123l));

This will only work in Java >1.4 and if no = could be in the key or value

edited Feb 26, 2013 at 9:12

answered Feb 26, 2013 at 9:05

Kai

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Comments

PeakGen · Accepted Answer · 2013-02-26 09:25:45Z

0

public class StringReplace
{
    public static void main(String[]args)
    {
        String str1 = "key1=value";
        String rep = "=(Long)";

        //Printing Current String
        System.out.println(str1);

        //Replacing the String
        str1 = str1.replaceAll("=", rep);

        //Printing new value
        System.out.println(str1);
    }
}

Use replaceAll() or replace() to replace all the matches found.

The above is the easiest way. You can go with loops checking for matches as well. But it will take lot of memory, if you are checking for lot of matches, it will be a panic.

edited Feb 26, 2013 at 9:25

answered Feb 26, 2013 at 9:12

PeakGen

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3 Comments

Rohit Jain Over a year ago

You don't really need a replaceAll here. Simply using str1.replace would suffice.

PeakGen Over a year ago

@RohitJain: I believe it is using an algorithm which uses less memory

Rohit Jain Over a year ago

The only difference between them is, replaceAll takes regex as parameter, whereas, replace does simple string replacement. You can also look into their source code for implementations.

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