Programowanie w języku Java - System wejścia-wyjścia (Java I/O System)

import java.io.*;
public class CopyFile {

   public static void main(String args[]) throws IOException {
      FileInputStream in = null;
      FileOutputStream out = null;

      try {
         in = new FileInputStream("input.txt");
         out = new FileOutputStream("output.txt");

         int c;
         while ((c = in.read()) != -1) {
            out.write(c);
         }
      }finally {
         if (in != null) {
            in.close();
         }
         if (out != null) {
            out.close();
         }
      }
   }
}

import java.io.*;
public class CopyFile {

   public static void main(String args[]) throws IOException {
      FileReader in = null;
      FileWriter out = null;

      try {
         in = new FileReader("input.txt");
         out = new FileWriter("output.txt");

         int c;
         while ((c = in.read()) != -1) {
            out.write(c);
         }
      }finally {
         if (in != null) {
            in.close();
         }
         if (out != null) {
            out.close();
         }
      }
   }
}

import java.io.*;
public class FileStreamTest {

   public static void main(String args[]) {

      try {
         byte bWrite [] = {11,21,3,40,5};
         OutputStream os = new FileOutputStream("test.txt");
         for(int x = 0; x < bWrite.length ; x++) {
            os.write( bWrite[x] );   // writes the bytes
         }
         os.close();

         InputStream is = new FileInputStream("test.txt");
         int size = is.available();

         for(int i = 0; i < size; i++) {
            System.out.print((char)is.read() + "  ");
         }
         is.close();
      }catch(IOException e) {
         System.out.print("Exception");
      }
   }
}

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;

public class BufferedReaderDemo {

   public static void main(String[] args) throws Exception {
      String thisLine = null;

      try {

         // open input stream test.txt for reading purpose.
         BufferedReader br = new BufferedReader("c:/test.txt");

         while ((thisLine = br.readLine()) != null) {
            System.out.println(thisLine);
         }
      } catch(Exception e) {
         e.printStackTrace();
      }
   }
}

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.StringWriter;

public class BufferedWriterDemo {

   public static void main(String[] args) throws IOException {
      StringWriter sw = null;
      BufferedWriter bw = null;

      String str = "Hello World!";

      try {

         // create string writer
         sw = new StringWriter();

         //create buffered writer
         bw = new BufferedWriter(sw);

         // writing string to writer
         bw.write(str);

         // forces out the characters to string writer
         bw.flush();

         // string buffer is created
         StringBuffer sb = sw.getBuffer();

         //prints the string
         System.out.println(sb);

      } catch(IOException e) {

         // if I/O error occurs
         e.printStackTrace();
      } finally {

         // releases any system resources associated with the stream
         if(sw!=null)
            sw.close();
         if(bw!=null)
            bw.close();
      }
   }
}

public void readFile(String filePath) throws IOException {
  FileReader fileReader = new FileReader(filePath);
  BufferedReader bufferedReader = new BufferedReader(fileReader);

  try {
    String textLine = bufferedReader.readLine();
    do {
      System.out.println(textLine);

      textLine = bufferedReader.readLine();
    } while (textLine != null);
  } finally {
    bufferedReader.close();
  }
}

public void writeFile(String filePath, String[] textLines)
    throws IOException {

  FileWriter fileWriter = new FileWriter(filePath);
  BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);

  try {
    for (String line : textLines) {
      bufferedWriter.write(line);
      bufferedWriter.newLine();
    }
  } finally {
    bufferedWriter.close();
  }
}

import java.io.IOException;
import java.io.RandomAccessFile;
 
public class RandomAccessFileExample {
 
    public static void main(String[] args) {
        try {
            String filePath = "source.txt";
            System.out.println(new String(readCharsFromFile(filePath, 1, 5)));
             
            writeData(filePath, "Data", 5);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
 
    private static void writeData(String filePath, String data, int seek) throws IOException {
        RandomAccessFile file = new RandomAccessFile(filePath, "rw");
        file.seek(seek);
        file.write(data.getBytes());
        file.close();
    }
 
    private static byte[] readCharsFromFile(String filePath, int seek, int chars) throws IOException {
        RandomAccessFile file = new RandomAccessFile(filePath, "r");
        file.seek(seek);
        byte[] bytes = new byte[chars];
        file.read(bytes);
        file.close();
        return bytes;
    }
 
}