The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
The for
statement provides a compact way to iterate over a range of values. Programmers often refer to it as the "for loop" because of the way in which it repeatedly loops until a particular condition is satisfied. The general form of the for
statement can be expressed as follows:
for (initialization; termination; increment) { statement(s) }
When using this version of the for
statement, keep in mind that:
false
, the loop terminates.The following program,
ForDemo
, uses the general form of the for
statement to print the numbers 1 through 10 to standard output:
class ForDemo { public static void main(String[] args){ for(int i=1; i<11; i++){ System.out.println("Count is: " + i); } } }
The output of this program is:
Count is: 1 Count is: 2 Count is: 3 Count is: 4 Count is: 5 Count is: 6 Count is: 7 Count is: 8 Count is: 9 Count is: 10
Notice how the code declares a variable within the initialization expression. The scope of this variable extends from its declaration to the end of the block governed by the for
statement, so it can be used in the termination and increment expressions as well. If the variable that controls a for
statement is not needed outside of the loop, it's best to declare the variable in the initialization expression. The names i
, j
, and k
are often used to control for
loops; declaring them within the initialization expression limits their life span and reduces errors.
The three expressions of the for
loop are optional; an infinite loop can be created as follows:
// infinite loop for ( ; ; ) { // your code goes here }
The for
statement also has another form designed for iteration through
Collections and
arrays This form is sometimes referred to as the enhanced for statement, and can be used to make your loops more compact and easy to read. To demonstrate, consider the following array, which holds the numbers 1 through 10:
int[] numbers = {1,2,3,4,5,6,7,8,9,10};
The following program,
EnhancedForDemo
, uses the enhanced for
to loop through the array:
class EnhancedForDemo { public static void main(String[] args){ int[] numbers = {1,2,3,4,5,6,7,8,9,10}; for (int item : numbers) { System.out.println("Count is: " + item); } } }
In this example, the variable item
holds the current value from the numbers array. The output from this program is the same as before:
Count is: 1 Count is: 2 Count is: 3 Count is: 4 Count is: 5 Count is: 6 Count is: 7 Count is: 8 Count is: 9 Count is: 10
We recommend using this form of the for
statement instead of the general form whenever possible.