Android™ How to Program, Second Edition

B.7. Floating-Point Numbers and Type double

We now depart temporarily from our GradeBook case study to declare an Account class that maintains the balance of a bank account. Most account balances are not whole numbers (such as 0, –22 and 1024). For this reason, class Account represents the account balance as a floating-point number (i.e., a number with a decimal point, such as 7.33, 0.0975 or 1000.12345). Java provides two primitive types for storing floating-point numbers in memory—float and double. They differ primarily in that double variables can store numbers with larger magnitude and finer detail (i.e., more digits to the right of the decimal point—also known as the number’s precision)than float variables.