If
layout: default
title: if Statement
We know if statements in everyday language. If some condition is true, an action follows.
- "If it is raining, I will take my umbrella."
- "If you don't bathe, you will not be very popular."
- "If you keep shouting at that horse, you will have a bad day."
In Java, an if statement controls whether a statement (or group of statements) executes.
* Its basic format is below, in pseudo code.
if ( expression evaluating to true )
statement
pseudo code¶
Text that looks like code but may not compile. Its purpose is to explain what code does.
Our English examples above might look like
boolean isRaining = false;
// ... code to determine if it's raining
if (isRaining == true)
takeUmbrella();
boolean doesBathe = false;
int popularityLevel = 100;
// ...
if (doesBathe == false)
popularityLevel = 0;
boolean shoutingAtHorse = false;
// ...
if (shoutingAtHorse)
haveBadDay();
The condition in parentheses has to evaluate to true for the next statement to execute.
* Note the difference between the first (raining) and third (shouting) examples.
* Since shoutingAtHorse is a boolean, it is already true or false.
Practice Exercise¶
Some programming languages allow values that do not evaluate to true or false in conditions. For example, a language may consider 0 to be the same as false and 1 to be the same as true.
Java is not one of these languages. The condition must evaluate to a boolean value.