Lesson 10: OR Operator - Intro to Java

OR Operator Combine conditions with || (OR).

1public static void main(String[] args) {

2 boolean isTrue = true;

3 boolean isFalse = false;

4 if (isTrue || isFalse) {

5 System.out.println("at least one is true");

6 }

Terminal

$ javac Main.java

$ java Main

at least one is true

Every line, explained

public static void main(String[] args) {: Every Java program starts at the main method. When you run the program, Java looks for this exact line, public static void main(String[] args), and runs everything between its { and } from top to bottom.
boolean isTrue = true;: boolean declares a variable that can store only one of two values: true or false. Watch the spelling: in Java the type is boolean; writing bool (like some other languages use) will not compile.
boolean isFalse = false;: boolean declares a variable that can store only one of two values: true or false. Watch the spelling: in Java the type is boolean; writing bool (like some other languages use) will not compile.
if (isTrue || isFalse) {: if checks the condition inside its parentheses. If the condition is true, Java runs the code between the { and }. If it is false, Java skips that code completely. || means OR: the whole condition is true if at least one side is true. true || false is true, so the block runs.
System.out.println("at least one is true");: System.out.println(...) prints whatever is inside the parentheses to the terminal, then moves to a new line. Read the name carefully: print-l-n is short for "print line".
}: This } closes the if block.
}: This closing curly brace } ends the main method. In Java every opening brace { must have a matching closing brace }.