Practical Coding in Java

Conditions and Comparisons

if (n == 7)
    doSomething();

You have already been using conditional statements (if statements) and comparisons (e.g. ==, <, …). This section includes some details that you should keep in mind as you code.

Braces

If you want to do more than one thing, you need to use braces { ... }. The code within the braces runs if the condition is true.

boolean condition = true;

if (condition)
{
    doSomething();
    doSomethingElse();
}

In general, braces specify a scope for local variables. Variables declared within a scope cannot be accessed outside of that scope.

Comparison Operators

The comparison operators in Java (==, <, >, <=, >=, !=) are binary operators (they take two input values) that return a boolean value.

if (i%3 == 0)
{
    System.out.println("Fizz");
}

Logical Operators

The logical operators && and || are binary operators that take two boolean values as input. The logical operator ! is a unary operator that takes a single boolean value as input. See the next section for more details on the logical operators.

if-else chains

You can add as many else if conditions as you want. The conditions are checked in order. If there is a final else statement, this code is run if none of the other conditions hold.

if (i%2 == 0)
{
    System.out.println("Even");
}
else if (i == 7 || i == 3)
{
    System.out.println("Lucky");
}
else
{
    System.out.println(i);
}