# Java Notes

# Loop Idioms

Loops are often used to accomplish the same kinds of tasks, so many loops tend to be one of several common styles.

## Loop reading input

It's very common to read input in a loop: read a value, process it, go back to read another, etc. Many beginning programs have this structure for reading input from the user. When a standard GUI (Graphical User Interface) is used, loops are not used, but loops are still used to read from files or over the internet.

## Loop a fixed number of times

Sometimes you just want to do something a fixed number of times.

## Loop over a String using an index

A common problem is move sequentially over each character position in a string to look for something, or to get the character and do something.

## Loop over an array with an index

## Loop over a data structure - using iterator

## Loop over a data structure - using for-each