BitSet nextSetBit() method in Java
BitSet is a class defined in the java.util package. It creates an array of bits represented by boolean values.
Prerequisite : Java BitSet | Set 1
nextSetBit() method :
This method in BitSet Class is used to return the index of the first bit that is set to true, that occurs on or after the specified starting index. If no such bit exists then -1 is returned.
Syntax:
public int nextSetBit(int fromIndex)
Parameters: This method takes a mandatory parameter fromIndex which is the index to start checking from (inclusive) for the next true bit.
Return Value: This method returns the index of the next set bit, or -1 if there is no such bit
Exception: This method throws IndexOutOfBoundsException if the specified index is negative.
Note : To iterate over the true bits in a BitSet, use the following loop:
for (int i = bs.nextSetBit(0); i >= 0; i = bs.nextSetBit(i+1)) {
// operate on index i here
}
Example 1: To show the implementation of nextSetBit() function :
import java.util.*;
public class GFG {
public static void main(String[] args)
{
BitSet bs1 = new BitSet();
BitSet bs2 = new BitSet();
BitSet bs3 = new BitSet();
bs1.set( 0 );
bs1.set( 1 );
bs1.set( 2 );
bs1.set( 4 );
bs2.set( 4 );
bs2.set( 6 );
bs2.set( 5 );
bs2.set( 1 );
bs2.set( 2 );
bs2.set( 3 );
bs2.set( 12 );
System.out.println( "bs1 : " + bs1);
System.out.println( "bs2 : " + bs2);
System.out.println( "bs3 : " + bs3);
System.out.println(bs1.nextSetBit( 2 ));
System.out.println(bs2.nextSetBit( 0 ));
System.out.println(bs3.nextSetBit( 3 ));
}
}
|
Output:
bs1 : {0, 1, 2, 4}
bs2 : {1, 2, 3, 4, 5, 6, 12}
bs3 : {}
2
1
-1
Example 2: To show IndexOutOfBoundException:
import java.util.*;
public class GFG {
public static void main(String[] args)
{
BitSet bs1 = new BitSet();
BitSet bs2 = new BitSet();
bs1.set( 0 );
bs1.set( 1 );
bs1.set( 2 );
bs1.set( 4 );
bs2.set( 4 );
bs2.set( 6 );
bs2.set( 5 );
bs2.set( 1 );
bs2.set( 2 );
bs2.set( 3 );
bs2.set( 12 );
System.out.println( "bs1 : " + bs1);
System.out.println( "bs2 : " + bs2);
try {
System.out.println(bs1.nextSetBit(- 1 ));
}
catch (Exception e) {
System.out.println( "Exception when "
+ "negative index is passed "
+ "as parameter : " + e);
}
}
}
|
Output:
bs1 : {0, 1, 2, 4}
bs2 : {1, 2, 3, 4, 5, 6, 12}
Exception when negative index is passed as parameter : java.lang.IndexOutOfBoundsException: fromIndex < 0: -1
Last Updated :
28 Aug, 2018
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