DataInputStream readLong() method in Java with Examples - GeeksforGeeks

05 Jun, 2020
The readLong() method of DataInputStream class in Java is used to read eight input bytes and returns a long value. This method reads the next eight bytes from the input stream and interprets it into long type and returns.
Syntax:
public final long readLong()
                  throws IOException

Specified By: This method is specified by readLong() method of DataInput interface.
Parameters: This method does not accept any parameter.
Return value: This method returns the long value interpreted by the next eight bytes of the input stream.
Exceptions:
EOFException – It throws EOFException if the input stream is ended before eight bytes can be read.
IOException – This method throws IOException if the stream is closed or some other I/O error occurs.
Below programs illustrate readLong() method in DataInputStream class in IO package:
Program 1: Assume the existence of file “demo.txt”.
// Java program to illustrate// DataInputStream readLong() methodimport java.io.*;public class GFG {    public static void main(String[] args)        throws IOException    {          // Create long array        long[] buf = { 10000000000l,                       20000000000l,                       30000000000l };          // Create file output stream        FileOutputStream outputStream            = new FileOutputStream("c:\\demo.txt");          // Create data output stream        DataOutputStream dataOutputStr            = new DataOutputStream(outputStream);          for (long b : buf) {            // Write long value to            // the dataOutputStream            dataOutputStr.writeLong(b);        }          dataOutputStr.flush();          // Create file input stream        FileInputStream inputStream            = new FileInputStream("c:\\demo.txt");          // Create data input stream        DataInputStream dataInputStr            = new DataInputStream(inputStream);          while (dataInputStr.available() > 0) {            // Print long values            System.out.println(                dataInputStr.readLong());        }    }}
Program 2: Assume the existence of file “demo.txt”.
// Java program to illustrate// DataInputStream readLong() methodimport java.io.*;public class GFG {    public static void main(String[] args)        throws IOException    {          // Create long array        long[] buf = { 1234567890L,                       9876543210L,                       12345678910L };          // Create file output stream        FileOutputStream outputStream            = new FileOutputStream("c:\\demo.txt");          // Create data output stream        DataOutputStream dataOutputStr            = new DataOutputStream(outputStream);          for (long b : buf) {            // Write long value to            // the dataOutputStream            dataOutputStr.writeLong(b);        }          dataOutputStr.flush();          // Create file input stream        FileInputStream inputStream            = new FileInputStream("c:\\demo.txt");          // Create data input stream        DataInputStream dataInputStr            = new DataInputStream(inputStream);          while (dataInputStr.available() > 0) {            // Print long values            System.out.println(                dataInputStr.readLong());        }    }}
References:https://docs.oracle.com/javase/10/docs/api/java/io/DataInputStream.html#readLong()
Java-Functions
Java-IO package
Java
Java
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.
Different ways of Reading a text file in Java
Stream In Java
Constructors in Java
Exceptions in Java
Generics in Java
Functional Interfaces in Java
HashMap get() Method in Java
Comparator Interface in Java with Examples
Strings in Java
StringBuilder Class in Java with Examples