# 5.12. Conditional - Summary¶

In this chapter you learned about conditionals. Conditionals are used to execute code when a Boolean expression is true or false. A Boolean expression is one that is either true or false like `x > 0`.

## 5.12.1. Concept Summary¶

• Block of statements - One or more statements enclosed in an open curly brace ‘{‘ and a closing curly brace ‘}’.

• Boolean expression - A mathematical or logical expression that is either true or false.

• complex conditional - A Boolean expression with two or more conditions joined by a logical and ‘&&’ or a logical or ‘||’.

• conditional - Used to execute code only if a Boolean expression is true.

• DeMorgan’s Laws - Rules about how to distribute a negation on a complex conditional.

• logical and - Used to only execute the following statement or block of statements if both conditions are true

• logical or - Used to execute the following statement or block of statements if one of the conditions are true

• negation - turns a true statement false and a false statement true

• short circuit evaluation - The type of evaluation used for logical and ‘&&’ and logical or ‘||’ expressions. If the first condition is false in a complex conditional with a logical and the second condition won’t be evaluated. If the first condition is true is a complex conditional with a logical or the second condition won’t be evaluated.

## 5.12.2. Java Keyword Summary¶

• if (Boolean expression) - used to start a conditional statement. This is followed by a statement or a block of statements that will be executed if the Boolean expression is true.

• else - used to execute a statement or block of statements if the Boolean expression on the if part was false.

• else if (Boolean expression) - used to have 3 or more possible outcomes such as if x is equal, x is greater than, or x is less than some value. It will only execute if the condition in the ‘if’ was false and the condition in the else if is true.