How to Use I/O Streams in Java

Step-by-Step Guide

1. 1

   Step 1: Create a text file.

   Give it an arbitrary name and write something in it, such as I love LifeGuide Hub!.
   
   In this article, we will name it file.txt. , You can add throws IOException declaration to the method signature to avoid adding the catch block to the try-with-resources block. public static void main(String[] args) { } , Try-with-resources block will automatically close streams for us. public static void main(String[] args) { try () { } } , In the constructor of the created input stream, specify the name of the text file previously created.
   
   In this article, we called it file.txt. public static void main(String[] args) { try (FileInputStream in = new FileInputStream("file.txt")) { } } The former is a byte stream, the latter is a character stream. , In the constructor of the created output stream, specify another arbitrary text file name.
   
   In this article, we will name it file-copy.txt. public static void main(String[] args) { try ( FileInputStream in = new FileInputStream("file.txt"); FileOutputStream out = new FileOutputStream("file-copy.txt") ) { } } If you created FileInputStream, you need to create FileOutputStream.
   
   The same goes for the FileReader and FileWriter. , This variable will be used for temporary storage of read byte or character. public static void main(String[] args) { try ( FileInputStream in = new FileInputStream("file.txt"); FileOutputStream out = new FileOutputStream("file-copy.txt") ) { int data; } } , Create a while loop in which the data is read into the previously created int variable until it reads the number
   -1.
   
   In other words, it reads data from the file until it reaches the end of the file. public static void main(String[] args) { try ( FileInputStream in = new FileInputStream("file.txt"); FileOutputStream out = new FileOutputStream("file-copy.txt") ) { int data; while ((data = in.read()) !=
   -1) { } } } , In the body of the while loop, write the read data to the output stream. public static void main(String[] args) { try ( FileInputStream in = new FileInputStream("file.txt"); FileOutputStream out = new FileOutputStream("file-copy.txt") ) { int data; while ((data = in.read()) !=
   -1) { out.write(data); } } } , Add a catch block to the try-with-resources block, catch IOException and, in case of an error, print the stack trace to the console. public static void main(String[] args) { try ( FileInputStream in = new FileInputStream("file.txt"); FileOutputStream out = new FileOutputStream("file-copy.txt") ) { int data; while ((data = in.read()) !=
   -1) { out.write(data); } } catch (IOException e) { e.printStackTrace(); } } , Contents of the file.txt are copied to the file-copy.txt which, if it doesn't exist yet, is created.
2. 2

   Step 2: Create a main method.

3. 3

   Step 3: Create a try-with-resources block.

4. 4

   Step 4: Create FileInputStream or FileReader in the block statement.

5. 5

   Step 5: Create FileOutputStream or FileWriter in the block statement.

6. 6

   Step 6: Create int variable.

7. 7

   Step 7: Read data from input stream.

8. 8

   Step 8: Write data to the output stream.

9. 9

   Step 9: Catch and handle IOException.

10. 10

    Step 10: Run the program.

Detailed Guide

About the Author