Scrolling TextView in a ScrollView to a specific substring of text

Question

For starters, I'm a C++/Qt Developer jumping into Android/Java development, so please don't assume I know anything. :) So, I have an application with a TextView contained with in a ScrollView. The text contained in the TextView is the results of a web query from my web server application. Depending on the query, the text can be pretty long. I want to implement a search feature on the text where the user enters some text string to search for, and if the text string is found, the ScrollView will scroll the TextView to ensure the entered substring is visible, and I want the text highlighted. I think I know how to highlight the text substring, I know how to tell the ScrollView to scroll to a specific line number in the TextView, but for the life of me, I can't figure out how to find out what line number to scroll to to guarantee my substring is visible. Ie, I want to query the text view to give me the line number that the substring first occurs at. Eventually, I want to also implement a find next that goes to the next occurrence of the substring. Kind of like the Find feature in Firebox. Any assistance is greatly appreciated. Thanks in advance.

Answer 1

You need to find the position of the substring in the text yourself, e.g. with String.indexOf(). Once you know that position, you can look up the correct line in the TextView using the Layout.getLineForOffset() function:

int offset=myString.indexOf("search string");
int line = myTextView.getLayout().getLineForOffset(offset);