How do I use logical OR operator in regex?

You can use the | operator (logical OR) to match characters or expression of either the left or right of the | operator. For example the (t|T) will match either t or T from the input string.

package org.kodejava.example.regex;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class LogicalOrRegexDemo {
    public static void main(String[] args) {
        // Define regex that will search characters 't' or 'T'
        String regex = "(t|T)";

        // Compiles the pattern and obtains the matcher object.
        Pattern pattern = Pattern.compile(regex);
        String input = "The quick brown fox jumps over the lazy dog";
        Matcher matcher = pattern.matcher(input);

        // Find every match and print it
        while (matcher.find()) {
            System.out.format("Text \"%s\" found at %d to %d.%n",
                matcher.group(), matcher.start(), matcher.end());
        }
    }
}

The program print the following result:

Text "T" found at 0 to 1.
Text "t" found at 31 to 32.

How do I use the || operator in Java?

The || operator or conditional OR operator operates on two boolean expressions. This operator exhibit “short-circuiting” behavior, which means that the second operand is evaluated only if needed.

The || operator evaluate only boolean values. For an OR (||) expression it will return true if either of the operand is true. If the first operand resolves true, then the second operand will not evaluated, because the complete expression will return true.

package org.kodejava.example.fundamental;

public class ConditionalORDemo {
    public static void main(String[] args) {
        // the second operand (5<3) is not evaluated, because the
        // first operand return true, the result of complete
        // expression will be true
        boolean a = (1 == 1) || (5 < 3);

        // the first operand return false, the second operand is
        // evaluated to check the result of the second expression.
        // If the second operand resolves to true, the complete
        // expression return true, otherwise return false.
        boolean b = (5 < 3) || (2 == 3);
        boolean c = (5 < 3) || (1 == 1);

        System.out.println("result a: " + a);
        System.out.println("result b: " + b);
        System.out.println("result c: " + c);
    }
}

The program prints the following output:

result a: true
result b: false
result c: true

How do I do bitwise OR operation?

package org.kodejava.example.lang;

public class ORDemo {
    public static void main(String[] args) {
        int numberA = 16;
        int numberB = 4;

        // Operator "|" is used for doing bitwise OR operation
        int result = numberA | numberB;

        System.out.println(numberA + " | " + numberB + " = " + result);

        // Print the result in binary format
        System.out.println(Integer.toBinaryString(numberA) +
                " | " + Integer.toBinaryString(numberB) +
                " = " + Integer.toBinaryString(result));
    }
}

The result of the code snippet:

16 | 4 = 20
10000 | 100 = 10100