File Output

Objectives

1. Write data to a file.

Notes

• A quick discussion on writing to a file.
• There are many ways to accomplish this.
• The method I am going to show you mimics what we have been doing all along
• First include java.io.PrintWriter
  • reference.
  • This has All of the methods of System.out
    • print, printf, println, close
  • But writes to a file.
• You create a file writer just like we created a scanner.
  • In a try/catch block.
  • But you pass it a file name when you create a new one.
• Some example code

  import java.io.PrintWriter;
  
  public class FileMaker{
     public static void main(String[] args) {
          PrintWriter writer = null;
          String fileName = "output.txt";
  
          try {
              writer = new PrintWriter(fileName);
          } catch (Exception e) {
              System.out.printf("Could not open %s\n",fileName);
              return;
          }
  
          writer.println("Writing to a file");
  
          for(int i =0; i < 10; ++i) {
             writer.printf("i = %d\n",i);
          }
  
          writer.close();
     }
  }