Statements

Actions are defined by a list of statements that are instructions to be executed in some sequence. A statement can include one or more expressions.

Variable declarations

Declaration statements declare variables and constants, specifying their data type, name, and initial value. Some examples are given in the following:.

int a = 42;

The declaration statement above declares a variable named a of type int and assigns it the value 42.

String text = "Hello";

The declaration statement above declares a variable named text of type String and assigns it the value "Hello".

A variable data type may also be some object type.

Person person = Person.Person();

The declaration statement above declares a variable named person of type Parson and assigns the variable to a new object of type Person;

Expression statements

x = 14;
foo.callToAMethod();

One can always use an expression as a statement. Thus, assignments can be declared (which are formally expressions) and methods can be called.

Statement block

x = 15;
{
  int y = 13;
  foo.someMethodCall();
}

Statement blocks can be used to structure code. Usually, they are used for structuring control statements. On the other side, one can instead use single statements, such as

if (condition) thenStatement;
else elseStatement;

But this is discouraged.

Control statements

If-else

if (condition) {
  // Statements
} else {
  // Statements
}

While loop

while (condition) {
  // Statements
}

Do-while loop

do {
  // Statements
} while (condition)

First executes the statements block following the do. After each execution of the statement block, the condition is evaluated. If it evaluates to true, then the statement block is executed again.

For loop

There are three different versions of the for loop.

// Creating control variables:
for (int i = expr, j = expr; condition; i++, j--) {
  // Statements
}

First, new variables are created. The condition that decides whether the next round of the loop should be executed is declared following a semicolon. After another semicolon, expressions are defined that are executed at the end of each loop.

// Initializing existing control variables
for (i = expr, j = expr; condition; i++, j--) {
  // Statements
}

Same as before, but the control variables already exist.

// For-iteration
for (int val : IntCollection) {
  // Statements
}

Iterating over a collection of items.

Switch

switch (expression) {
  case CONSTANT_OR_ENUM_VAL: /* statements */ break;
  default: /* statements */ break;
}

evaluates the expression and depending on whether it is equal to a constant or enumeration value, it executes the statements declared within the respective cases. These statement definitions must be terminated with a break; statement. The statements of the default case are executed if the evaluated expression value does not match any other case.

Break

The break; statement is not only available in switch statements, but also in loops in which they terminate the loop early.