Start of Tutorial > Start of Trail > Start of Lesson

Search Feedback Form

Control Flow Statements

When you write a program, you type statements into a file. Without control flow statements, the interpreter executes these statements in the order they appear in the file from left to right, top to bottom. You can use control flow statements in your programs to conditionally execute statements, to repeatedly execute a block of statements, and to otherwise change the normal, sequential flow of control. For example, in the following code snippet, the if statement conditionally executes the System.out.println statement within the braces, based on the return value of Character.isUpperCase(aChar):

char aChar;
...
if (Character.isUpperCase(aChar)) {
    System.out.println("The character " + aChar
                       + " is upper case.");
}

The Java programming language provides several control flow statements, which are listed in the following table.

Control-Flow Statements

Statement Type	Keyword
looping	while, do-while, for
decision making	if-else, switch-case
exception handling	try-catch-finally, throw
branching	break, continue, label:, return

In the sections that follow, you will see the following notation to describe the general form of a control flow statement:

control flow statement details {
    statement(s)
}

Technically, the braces, { and }, are not required if the block contains only one statement. However, we recommend that you always use { and }, because the code is easier to read and it helps to prevent errors when modifying code.

Start of Tutorial > Start of Trail > Start of Lesson

Search Feedback Form

Copyright 1995-2005 Sun Microsystems, Inc. All rights reserved.