“Introduction to Programming With Java”

“Introduction to Programming With Java” Lecture - 16 UMESHPATIL (umesh@cse.iitb.ac.in) nlp-ai@cse.iitb

Contents for Today’s Lecture • Revision of File-Reading • Writing to files • Example programs on file handling nlp-ai@cse.iitb

Revision of File-Reading • Commands for opening the file for reading: • FileReader fr = new FileReader(“input.txt”);BufferedReader br = new BufferedReader(fr); • Command for reading one line from the opened file: • String str = br.readLine(); • Command for closing the opened file: • br.close(); nlp-ai@cse.iitb

FileRead.java nlp-ai@cse.iitb

File-Writing • Commands for opening the file for writing: • FileWriter fw = new FileWriter(“output.txt”);BufferedWriter bw = new BufferedWriter(fr); • Command for writing a String to the opened file: • bw.write(str); // str is a String • Command for closing the opened file: • bw.close(); nlp-ai@cse.iitb

FileWrite.java nlp-ai@cse.iitb

Examples • Write a File-Copy program which copies the content of one file to another. Take both the file names from the user. • Write a Java program for expanding abbreviations in the input text. Store the expanded output in one file. Input text is read from a file. Get the input and output file names from the user. Abbreviations along with their expansions are stored in the file ‘abbreviations.txt’ in the format:<line i>abbreviation<line i+1>expansion nlp-ai@cse.iitb

ExpandAbbreviation Algorithm • Read abbreviations & expansions from file and store in arrays • Open input file for reading • Open output file for writing • For each line in the input file • Search for each abbreviation in the line and replace if found(find_and_replace() function) • Write the modified line to the output file • Close all opened files nlp-ai@cse.iitb

ExpandAbbreviation.java nlp-ai@cse.iitb

Exercise • Write a Java program for reading a dictionary file for counting the no. of dictionary entries in the file. Each line in the file consists of one dictionary entry. nlp-ai@cse.iitb

End Thank you  nlp-ai@cse.iitb

“Introduction to Programming With Java”