Replace parameters that can be changed in string using regex

Question

Let's say I have a string, different version of the input string:

a) Name='book' Number='345' Version='12' Author='name1'
b) Name='book' Version='12' Author='name1' Number='345'

I need to remove Version='xx' and Number='xx'from this input string. Values of this parameters can be always changed.

What is the best way to do it? I tried regex, something like:

String input = input.substring(0, input.indexOf("Number")) + "" + input.substring(input.indexOf("Version"));

But that would work only for this case:

a) Name='book' Number='345' Version='12' Author='name1'

But not for this:

b) Name='book' Version='12' Author='name1' Number='345'

So how to make a general approach?

ernest_k · Accepted Answer · 2018-09-21 16:06:21Z

5

You can use a regular expression to replace:

"Name='book' Number='345' Version='12' Author='name1'"
    .replaceAll("( Number| Version)='\\d+'", "")

That returns Name='book' Author='name1'

replaceAll("( Number| Version)='\\d+'", "") finds Number OR Version followed by a number in single quotes, and replaces it with a blank string.

As suggested by Aaron's comment below, if the order of key/value pairs can change, then a different regex may be better:

s.replaceAll("(?:^| )(?:Number|Version)='\\d+'", "").trim()

This will match the keys whether they're preceded by a space or are at the beginning of the line.

edited Sep 21, 2018 at 16:06

answered Sep 21, 2018 at 15:44

ernest_k

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6 Comments

Aaron Over a year ago

Aren't you missing a group around the Number| Version alternation? Name='book'='345' doesn't look right to me

Aaron Over a year ago

Another problem : since the order of the attributes seems variable, you should match them preceded by either space or the start of the string

ernest_k Over a year ago

@Aaron Makes perfect sense. I just have to find an explanation for why it works without the group.

Aaron Over a year ago

It doesn't, look at what you wrote it returned : Name='book'='345' likely isn't what OP wants ;)

ernest_k Over a year ago

@Aaron 100% Thanks. I'm possibly sleep-typing. You're right

|

Emre Savcı · Accepted Answer · 2018-09-21 15:51:47Z

0

You can achieve what you want to do with regex using replaceAll method as below :

    String input = "Name='book' Number='345' Version='12' Author='name1'";
    String input2 = "Name='book' Version='345' Number='12' Author='name1'";

    input = input.replaceAll("(Number|Version)='\\d+'", "");
    input2 = input2.replaceAll("(Number|Version)='\\d+'", "");

    System.out.println(input);
    System.out.println(input2);

output is :

Name='book'   Author='name1'
Name='book'   Author='name1'

answered Sep 21, 2018 at 15:51

Emre Savcı

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