How do you read from an external file in java?

Answer 1

The class I find useful is the FileReader class in java.io. It allows you to read an external file in your program.

For instance,

Consider a file input.txt:

Hello

How are you?

1 2 3 4 5

You can access it by:

FileReader read = new FileReader("input.txt"); // pass the file name as a String

//now the read is the file

//can scan from the file using Scanner

Scanner scan = new Scanner(read);

System.out.println( scan.nextLine()); // prints Hello

System.out.println( scan.nextLine()); // prints How are you?

while(scan.hasNextInt())

System.out.print(scan.nextInt() + " "); // prints 1 2 3 4 5

Answer 2

For java 5.0, there is a really easy way to read text from a file, and there is an option to read whole objects from a file. = To read a Text external file = The simplest way is to use the Scanner Class: Scanner scan = new Scanner ( new File("[yourfilename]")); // and basically use all the scanner class's methods to access the file. // read a line String line = scan.nextLine(); // read a token (a section of non white space) String word = scan.next(); // read and integer or double int input1 = scan.nextInt(); double input2 = scan.nextDouble(); = To read objects from files will be added later =