In Java logical operators, if the evaluation of a logical expression exits in between before complete evaluation, then it is known as Short-circuit. A short circuit happens because the result is clear even before the complete evaluation of the expression, and the result is returned. Short circuit evaluation avoids unnecessary work and leads to efficient processing.
Below are the various types of Short circuits that occur in Java:
1. AND(&&) short circuit:
In the case of AND, the expression is evaluated until we get one false result because the result will always be false, independent of the further conditions. If there is an expression with &&(logical AND), and the first operand itself is false, then a short circuit occurs, the further expression is not evaluated, and false is returned.
Example: Short-circuiting using AND(&&) operator.
Java
// Java code to demonstrate the// short circuiting using && import java.io.*; class ShortCirAND { public static void main(String arg[]) { // Since first operand is false // and operator is &&, // Evaluation stops and // false is returned. if (false && true && true) { System.out.println("This output " + "will not " + "be printed"); } else { System.out.println("This output " + "got printed actually, " + " due to short circuit"); } // Whole expression will be evaluated, // as no false is encountered // before last condition // Therefore no Short circuit if (true && true && true) { System.out.println("This output " + "gets print" + " as there will be" + " no Short circuit"); } else { System.out.println("This output " + "will not " + "be printed"); } }} |
This output got printed actually, due to short circuit This output gets print as there will be no Short circuit
2. OR(||) short circuit:
In the case of OR, the expression is evaluated until we get one true result because the result will always be true, independent of the further conditions. If there is an expression with ||(logical OR), and the first operand itself is true, a short circuit occurs, evaluation stops, and true is returned.
Example: Short-circuiting using OR( || ).
Java
// Java program to demonstrate the// short circuiting using OR class ShortCirOR { public static void main(String arg[]) { // Since first operand is true // and operator is ||, // Evaluation stops and // true is returned. if (true || false || false) { System.out.println("This output " + "got printed actually, " + " due to short circuit"); } else { System.out.println("This output " + "will not " + "be printed"); } // Whole expression will be evaluated, // as no true is encountered // before last condition // Therefore no Short circuit if (false || false || true) { System.out.println("This output " + "gets print" + " as there will be" + " no Short circuit"); } else { System.out.println("This output " + "will not " + "be printed"); } }} |
This output got printed actually, due to short circuit This output gets print as there will be no Short circuit