Java DataInputStream class allows an application to read primitive data from the input stream in a machine-independent way. Java application generally uses the data output stream to write data that can later be read by a data input stream.

• DataInputStream(InputStream in) - Creates a DataInputStream that uses the specified underlying InputStream.

• int read(byte[] b) - Reads some number of bytes from the contained input stream and stores them into the buffer array b.
• int read(byte[] b, int off, int len) - Reads up to len bytes of data from the contained input stream into an array of bytes.
• boolean readBoolean() - See the general contract of the readBoolean method of DataInput.
• byte readByte() - See the general contract of the readByte method of DataInput.
• char readChar() - See the general contract of the readChar method of DataInput.
• double readDouble() - See the general contract of the readDouble method of DataInput.
• float readFloat() - See the general contract of the readFloat method of DataInput.
• void readFully(byte[] b) - See the general contract of the readFully method of DataInput.
• void readFully(byte[] b, int off, int len) - See the general contract of the readFully method of DataInput.
• int readInt() - See the general contract of the readInt method of DataInput.
• long readLong() - See the general contract of the readLong method of DataInput.
• short readShort() - See the general contract of the readShort method of DataInput.
• int readUnsignedByte() - See the general contract of the readUnsignedByte method of DataInput.
• int readUnsignedShort() - See the general contract of the readUnsignedShort method of DataInput.
• String readUTF() - See the general contract of the readUTF method of DataInput.
• static String readUTF(DataInput in) - Reads from the stream in a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as a String.
• int skipBytes(int n) - See the general contract of the skipBytes method of DataInput.

A program to read each primitive char type from file sample.txt.

import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
public class DataInputStreamExample {
	public static void main(String[] args) {
		try(InputStream input = new FileInputStream("sample.txt"); 
	 DataInputStream inst = new DataInputStream(input);){ 
	 int count = input.available(); 
	 
	 byte[] ary = new byte[count]; 
	 inst.read(ary); 
	 for (byte bt : ary) { 
	 char k = (char) bt; 
	 System.out.print(k+"-"); 
	 } 
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

Output:

T-h-e-r-e- -i-s- -s-o-m-e- -c-o-n-t-e-n-t- -i-n- -f-i-l-e- -
-n-e-w-l-i-n-e- -a-d-d-e-d- -t-o- -e-x-i-s-t-i-n-g- -f-i-l-e-
-

DataInputStream