urgent help needed in java i need part 3 only! Thanx

Part 3 needed !

words1.txt

Java is great. great wonderful

words2.txt

I love you. love hate

words3.txt

Welcome to the University of Cincinatti. Cincinatti Dayton

Write a program that reads in a line of text (string), two indexes (two ints index, and indexa) and a word (String) from a text file, and then outputs that line of text with the substring between indexi and indexa changed to word. For example, a possible sample dialogue might be the following (user input in color) File name: data2. tx Line of text read from file: I love you. starting index: 2 Ending index: 5 Word to look for love Replacement word: hate I have rephrased that line to read: I hate you You can assume that word, occurs in the input text. If word, occurs more than once in the line, your program should replace only the first occurrence of word The program should work for each of the following text files data1.t data2.txt . data3.xt