getBit() - Retrieving a Bit from a Byte Array

This section provides a tutorial example on how to get one bit back from a byte array at a specific bit position - getBit().

2. getBit() - To get one bit back from a bit string stored in a byte array at the specified position:

   private static int getBit(byte[] data, int pos) {
      int posByte = pos/8; 
      int posBit = pos%8;
      byte valByte = data[posByte];
      int valInt = valByte>>(8-(posBit+1)) & 0x0001;
      return valInt;
   }

Explanations:

To understand how the fifth statement works, let's assume that posBit = 2. Then the evaluation process of the statement can be described as:

valByte   : ???????? ???????? ???????? xxyxxxxx
>> 5
-----------------------------------------------
          = ???????? ???????? ???????? ?????xxy
& 0x0001  : 00000000 00000000 00000000 00000001
-----------------------------------------------
          = 00000000 00000000 00000000 0000000y

Last update: 2014.

Table of Contents

 About This Book

 Installing JDK 1.8 on Windows

 Execution Process, Entry Point, Input and Output

 Primitive Data Types and Literals

 Bits, Bytes, Bitwise and Shift Operations

Managing Bit Strings in Byte Arrays

 setBit() - Storing a Bit into a Byte Array

getBit() - Retrieving a Bit from a Byte Array

 rotateLeft() - Left Rotating All Bits in a Byte Array

 bitStringTest.java - Testing Program

 Reference Data Types and Variables

 StringBuffer - The String Buffer Class

 System Properties and Runtime Object Methods

 Generic Classes and Parameterized Types

 Generic Methods and Type Inference

 Lambda Expressions and Method References

 Execution Threads and Multi-Threading Java Programs

 ThreadGroup Class and "system" ThreadGroup Tree

 Synchronization Technique and Synchronized Code Blocks

 Deadlock Condition Example Programs

 Garbage Collection and the gc() Method

 Outdated Tutorials

 References

 PDF Printing Version