Exercises

Volume of a box

Declaring variables and using them in an expression

Perimeter of a rectangle

Combining parameters in an arithmetic expression

Hours to seconds

Converting between units with multiplication

Average of three

Using double for a value that is not a whole number

Positive or not

Returning a boolean from a comparison

Area of a rectangle

Calling a method with parameters and returning a value

Even or odd

Using the remainder operator and returning a boolean

What is left over

Using the remainder operator

Last digit

Extracting a digit with the remainder operator

Tens digit

Combining integer division and remainder

Money in cents

Converting to a single unit before calculating

How many quarters

Using integer division deliberately

Minutes left over

Reading a total as whole units plus a remainder

Say hello

Printing with System.out.println and joining Strings

Say it twice

Calling System.out.println more than once

Label a value

Joining text and numbers with +

Put it in quotes

Escaping a double quote inside a String

Two columns

Using the tab escape sequence

A Windows path

Escaping a backslash

A tiny receipt

Printing several lines that build one block of output

Add a tip

Updating a variable with +=

Spend some money

Updating a variable with -=

Double it twice

Updating a variable with *=

Halve it twice

Updating with /= and seeing integer division bite

Chop off the decimals

Casting a double to an int throws away the fraction

Round to the nearest whole number

Rounding with Math.round and casting the result

Average of two whole numbers

Avoiding integer division when the answer is not whole

What percentage

Ordering an expression so integer division does not destroy it

Celsius to Fahrenheit

Arithmetic with doubles, and integer division as a trap

Milliseconds in a day

Choosing a type large enough for the result

How long is it

Calling length() on a String

First letter

Taking one character out with substring

Last letter

Using length() to find the end of a String

The middle letter

Using substring with two positions

Shout it

Calling toUpperCase

Whisper it

Calling toLowerCase

Where does it appear

Calling indexOf and understanding -1

Are they the same word

Comparing Strings with equals rather than ==

Same word, any capitals

Calling equalsIgnoreCase

Initials

Calling String methods and building a String

Distance from zero

Calling Math.abs

How far apart

Combining subtraction with Math.abs

Square root

Calling Math.sqrt

Raise to a power

Using Math.pow and casting its double result

The bigger one

Calling Math.max

The largest of three

Nesting one method call inside another

Tidy up the spaces

Calling an instance method that returns a new object

Make it a hashtag

Calling replace on a String object

Is it in there

Calling contains and returning what it gives back

Put a name together

Chaining instance methods together

Add up the numbers

Using iteration to accumulate a value