BitSet in Java

Introduction

BitSet is a class in Java that represents a fixed-size sequence of bits. It provides a convenient way to manipulate and store bits. Each bit in a BitSet can have two values: 0 or 1. BitSet is an efficient data structure for handling large sets of flags or binary values. In this article, we will explore the usage of the BitSet class in Java with code examples.

Features of BitSet

  1. BitSet uses a compact representation of bits, where each bit is stored as a boolean value.
  2. The size of the BitSet is dynamic and can grow as needed.
  3. BitSet provides bitwise operations like AND, OR, NOT, and XOR, which makes it easy to perform operations on sets of bits.
  4. The BitSet class also supports operations like set, clear, flip, and get, which allow easy manipulation of individual bits.
  5. BitSet can be used to represent a set of integers efficiently by using the index of the BitSet as the value of the integer.

Creating a BitSet

To create a BitSet, you can simply instantiate the BitSet class:

import java.util.BitSet;

BitSet bitSet = new BitSet();

Setting and Getting Bits

You can set a bit at a specific index using the set method:

bitSet.set(3);

To clear a bit at a specific index, use the clear method:

bitSet.clear(3);

To check if a bit is set, use the get method:

boolean isSet = bitSet.get(3);

Bitwise Operations

BitSet provides several bitwise operations that can be used to perform operations on sets of bits. Here are some examples:

AND Operation

The AND operation sets a bit in the result if it is set in both operands.

BitSet bitSet1 = new BitSet();
bitSet1.set(0);
bitSet1.set(1);

BitSet bitSet2 = new BitSet();
bitSet2.set(1);
bitSet2.set(2);

bitSet1.and(bitSet2);

OR Operation

The OR operation sets a bit in the result if it is set in either operand.

BitSet bitSet1 = new BitSet();
bitSet1.set(0);
bitSet1.set(1);

BitSet bitSet2 = new BitSet();
bitSet2.set(1);
bitSet2.set(2);

bitSet1.or(bitSet2);

NOT Operation

The NOT operation inverts the bits of the BitSet.

BitSet bitSet = new BitSet();
bitSet.set(0);
bitSet.set(1);

bitSet.flip(0, 3);

XOR Operation

The XOR operation sets a bit in the result if it is set in one operand but not both.

BitSet bitSet1 = new BitSet();
bitSet1.set(0);
bitSet1.set(1);

BitSet bitSet2 = new BitSet();
bitSet2.set(1);
bitSet2.set(2);

bitSet1.xor(bitSet2);

State Diagram

Below is a state diagram representing the different states of a BitSet:

stateDiagram
    [*] --> Empty
    Empty --> Non-Empty
    Non-Empty --> Empty
    Non-Empty --> Non-Empty

Sequence Diagram

The following sequence diagram demonstrates the creation and manipulation of a BitSet:

sequenceDiagram
    participant User
    participant BitSet

    User->>BitSet: Create BitSet
    User->>BitSet: Set bit at index 3
    User->>BitSet: Clear bit at index 3
    User->>BitSet: Get bit at index 3
    User->>BitSet: Perform bitwise AND operation
    User->>BitSet: Perform bitwise OR operation
    User->>BitSet: Perform bitwise NOT operation
    User->>BitSet: Perform bitwise XOR operation

Conclusion

BitSet is a useful class in Java for handling sets of bits efficiently. It provides various operations to manipulate individual bits and perform bitwise operations on sets of bits. BitSet is widely used in applications that require efficient storage and manipulation of binary data. Understanding the features and usage of the BitSet class in Java can greatly simplify bit-level operations in your code.