The JavaTM Tutorial

| Start of Tutorial > Start of Trail > Start of Lesson | Search Feedback Form

Trail: Learning the Java Language
Lesson: Language Basics

## Summary of Control Flow Statements

### Loops

> Use the `while` statement to loop over a block of statements while a boolean expression remains true. The expression is evaluated at the top of the loop.

> >     while (boolean expression) {
> >         statements
> >     }

> Use the `do`-`while` statement to loop over a block of statements while a boolean expression remains true. The expression is evaluated at the bottom of the loop.

> >     do {
> >         statement
> >     } while (expression);

> The `for` statement loops over a block of statements and includes an initialization statement, a termination condition statement, and an increment statement.

> >     for (initialization ; termination ; increment) {
> >         statements
> >     }

### Decision-Making

> A basic `if` statement whose single statement block is executed if the boolean expression is true.

> >     if (boolean expression) {
> >         statements
> >     }

> An `if` statement with one boolean expression and two statement blocks. The first statement block is executed if the boolean expression is true and the second is executed if the boolean expression is false.

> >     if (boolean expression) {
> >         statements
> >     } else {
> >         statements
> >     }

> An `if` statement with multiple expressions.

> >     if (boolean expression) {
> >         statements
> >     } else if (boolean expression) {
> >         statements
> >     }

> An `if` statement with multiple expressions and an `else` statement.

> >     if (boolean expression) {
> >         statements
> >     } else if (boolean expression) {
> >         statements
> >     } else {
> >         statements
> >     }

> The `switch` statement evaluates and integer expression and executes the appropriate `case` statement.

> >     switch (integer expression) {
> >         case integer expression:
> >              statements
> >              break;
> >         ...
> >         default:
> >              statements
> >              break;
> >     }

### Exception-Handling

> Throw an exception to indicate that an error occurred.

> >     throw exception;

> Use the `try`, `catch`, and `finally` statements to handle exceptions.

> >     try {
> >         statements
> >     } catch (exceptiontype name) {
> >         statements
> >     } catch (exceptiontype name) {
> >         statements
> >     } finally {
> >         statements
> >     }

### Branching

> Use the unlabelled form of the `break` statement to terminate the innermost `switch`, `for`, `while`, or `do` statement.

> >     break;

> Use the labelled form of the `break` statement to terminate an outer `switch`, `for`, `while`, or `do` statement with the given label:

> >     break label;

> A `continue` statement terminates the current iteration of the innermost loop and evaluates the boolean expression that controls the loop.

> >     continue;

> The labelled form of the `continue` statement terminates the current iteration of the loop with the given label and evaluates the boolean expression that controls the loop.

> >     continue label;

> Use `return` to terminate the current method.

> >     return;

> You can return a value to the method's caller, by using the form of `return` that takes a value.

> >     return value;

| Start of Tutorial > Start of Trail > Start of Lesson | Search Feedback Form