Searching in a string a substring

Question

I have a string (Str) with phrases separated by a character (let's define it as "%" for simple understanding). I want to search for phrases in this string (Str) that contains a word (like "dog") and put that phrase in a new string

I was wondering of a good/great way to do it.

Str is the String on which I'm going to search, "Dog" is the word I'm searching for and % is the line separator.

I already have the reader, the parser and how to save that file. I would appreciate if someone finds me an easy way to search. I can do it but I think it would be too complex meanwhile the actual solution is very easy.

I had thought about searching for the lastIndexOf("dog") and searching for the "%" in the substring of Str(0, lastIndexOf("dog") and then the second % to get the line I am searching for.

P.S: There may be two "dog" in Str and I would like to have all the lines where is showed the word "dog"

Example:

Str = " Where is my dog, john ? % your dog is on the table % really thanks john % you're welcome % Have a nice dog"

Output expected:

Where is my dog, john ? // your dog is on the table // Have a nice dog"

Answer 1

You can use:

String str = "Where is my dog, john ? % your dog is on the table % really thanks john " +
             "% you're welcome % Have a nice dog";

String dogString = Arrays.stream(str.split("%"))            // String[]  
                     .filter(s -> s.contains("dog"))        // check if each string has dog
                     .collect(Collectors.joining("//"));    // collect to one string

which gives:

Where is my dog, john ? // your dog is on the table // Have a nice dog

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1. Here, the String is split into an array by using %
2. The array is filtered to check if the split sentence contains "dog" or not.
3. The resulting strings are concatenated into one using //.