Contoh Program Java: Operasi File

package java_file;
import java.io.FileNotFoundException;
import java.io.PrintStream;
import java.util.Scanner;
import java.io.File;

/**
 *
 * @author bluejundi
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)
    // TODO code application logic here
    throws FileNotFoundException {
    double unitPrice, quantity, total;
    PrintStream diskWriter = new PrintStream("databarang.txt");
    Scanner diskScanner = new Scanner(new File("cookedData.txt"));

/*   
    unitPrice = 1000;
    quantity = 5;
    total = unitPrice * quantity;
    //menulis ke file
    diskWriter.print(unitPrice+" ");
    diskWriter.print(quantity+" ");
    diskWriter.println(total);
    //membaca dr file
    unitPrice = diskScanner.nextDouble();
    quantity = diskScanner.nextDouble();
    total = diskScanner.nextDouble();
    System.out.println("Harga satuan : "+unitPrice);
    System.out.println("Jumlah barang: "+quantity);
    System.out.println("Total harga  : "+total);
*/  //membaca dan menulis
   

        int npm;
        String nama = new String("");
        double ipk;
        diskWriter = new PrintStream("mhs.txt"); //buat file
        int i;
        Scanner sc = new Scanner(System.in);
        System.out.print("Jumlah data = ");
        i = sc.nextInt();
        do
        {
            System.out.print("NPM = ");
            npm = sc.nextInt();
            System.out.print("Nama = ");
            nama = sc.next();
            System.out.print("IPK = ");
            ipk = sc.nextDouble();
            diskWriter.println(npm + " " + nama + " " + ipk);
            i--;
        }
        while(i>0);
        System.out.println("Isi File:");
        diskScanner = new Scanner(new File("mhs.txt"));
        while (diskScanner.hasNext())
        {
            npm = diskScanner.nextInt();
            nama = diskScanner.next();
            ipk = diskScanner.nextDouble();
            System.out.println("["+npm+"] "+nama+" ("+ipk+")");
        }
    }
}