# Java: if Statement - Overview

## Purpose

The purpose of the `if` statement is to make decisions, and execute different parts of your program depending on a boolean true/false value. About 99% of the flow decisions are made with `if`. [The other 1% of the decisions use the `switch/case` statement.]

## General Forms

The `if` statement has this form:

    do these statements
    if (condition) {
        do this clause if the condition is true
    }
    do these statements afterwards

or

    do these statements
    if (condition) {
        do this clause if the condition is true
    } else {
        do this clause if the condition is false
    }
    do these statements afterwards

It is good programming style to always write the curly braces, `{}`, altho they are not needed if the clause contains only a single statement.

## Condition is `true` or `false`

The value of condition must be `true` or `false` (ie, a `boolean` value). It is often a comparison.

    . . .
    if (marks < 60) {
        JOptionPane.showMessageDialog(null, "This is terrible");
    } else {
        JOptionPane.showMessageDialog(null, "Not so bad");
    }
    . . .

The code above will display one of two dialogs, depending on teh value of marks.