Converting arraylist to string

Question

I have a multiple line string that is taken as a user input. I broke the string into ArrayList by str.split("\\\\s ") and changed a particular word if it occurred, now i want to merge the words in the ArrayList with the replaced word in it and form the string again in a multiple line pattern only. I'm not getting how to do this. Please help.

Answer 1

Using only standard Java (assuming your ArrayList is called words )

StringBuilder sb = new StringBuilder();
for (String current : words) 
  sb.append(current).append(" ");
String s = sb.toString().trim();

If you have the Guava library you can use Joiner:

String s = Joiner.on(" ").join(words)

Both of these will work even if the type of words is String[] .

If you want to preserve the line structure, I suggest the following approach: first break the input string into lines by using .split("\\n") . Then, split each lines to words using .split("\\\\s") . Here's how the code should look like:

public String convert(String input, String wordToReplace, String replacement) {
  StringBuilder result = new StringBuilder();
  String[] lines = input.split("\n");
  for (String line : lines) {
    boolean isFirst = true;
    for (String current : line.split("\\s")) {
      if (!isFirst)
        result.append(" ");
      isFirst = false;
      if (current.equals(wordToReplace))
        current = replacement;
      result.append(current);
    }
    result.append("\n");
  }

  return result.toString().trim();
}