Java – Read File as InputStream

In this tutorial, you will learn how to read a file as InputStream in Java, using FileInputStream class and InputStream class of java.io.

Java – Read file as InputStream

To read a file as InputStream in Java,

1. Given a file path, create a new instance of FileInputStream using the given file path, and assign it to an InputStream type object.
2. Read the input stream byte by byte using a Java While loop.

If filePath is the given file path, then use the following statement to get the InputStream.

InputStream inputStream = new FileInputStream(filePath)

1. Read the file “data.txt” as InputStream in Java

In the following program, we take a file path "/Users/tutorialkart/data.txt", read the content of this file using InputStream, and print the bytes of file one by one to standard output.

In the program,

1. Given a file path filePath as String.

String filePath = "/Users/tutorialkart/data.txt";

2. Use Java’s try with resource syntax to create the InputStream.
3. Create an instance of InputStream using FileInputStream() class. Store the InputStream object in a variable, say inputStream.

try (InputStream inputStream = new FileInputStream(filePath)) {
    
}

4. Inside the try block, read the content from inputStream byte by byte using While loop. Typecast the byte to char, and print it to output.

int byteRead;
while ((byteRead = inputStream.read()) != -1) {
    System.out.print((char) byteRead);
}

5. If there could be an IOException while handling the file, catch the IOException and address it in a catch block.

try( ) {
	
} catch (IOException e) {
    e.printStackTrace();
}

The following is the complete Java program, to read the file as InputStream, and then print the content of the InputStream.

Java Program

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

public class Main {
    public static void main(String[] args) {
        String filePath = "/Users/tutorialkart/data.txt";

        try (InputStream inputStream = new FileInputStream(filePath)) {
            int byteRead;
            while ((byteRead = inputStream.read()) != -1) {
                System.out.print((char) byteRead);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Output

hello world

Conclusion

In this Java File Operations tutorial, we learned how to read the file as InputStream using java.io.FileInputStream class, with examples.