Reading from a text file

To read strings of text from a file we have to:

1. open the file for reading by creating an object of the class FileReader and an object of the class BufferedReader associated to the FileReader object we have just created;
2. read the lines of text from the file by using the readLine() method of the BufferedReader object;
3. close the file when we are finished reading from it.

The Java statements that realize the three phases described above are:

// 1. opening the file for reading
FileReader f = new FileReader("test.txt");;
BufferedReader in = new BufferedReader(f);

// 2. reading a line of text from the file
String line = in.readLine();

// 3. closing the file
f.close();

Notes:

• If the file that we want to open for reading does not exist, then an exception of type FileNotFoundException is raised when the object FileReader is created.
• After we have opened the file, we start reading from the its first line. Then, each time we invoke the method readLine(), we advance the input to the next line, so that each invocation of readLine() will read the following line of text in the file.