Repeated Code
One of the best uses of methods is to avoid repeated code:
public class CalculateBalance {
public static void main(String[] args) {
double cost = 307.32;
double balance = cost;
double payment1 = 42.40;
balance = balance - payment1;
System.out.println("-----------------");
System.out.println("---- BALANCE ----");
System.out.println("-----------------");
System.out.println(balance);
System.out.println();
double payment2 = 39.31;
balance = balance - payment2;
System.out.println("-----------------");
System.out.println("---- BALANCE ----");
System.out.println("-----------------");
System.out.println(balance);
System.out.println();
}
}
The method repeats the exact same code for printing "BALANCE". * This code should be moved into its own method, which is then called twice from main.
We call this re-structuring of code refactoring.
refactoring¶
Changing code so that the program has the same functionality, but the code is better structured.
In other words, making a program better without breaking it.
Drill¶
Methods/src/drills/CalculateBalanceRefactor.java
We will refactor this class to print the header with a method.
* Declare a new method public static void printHeader().
* Copy the three System.out.println statements that print the "BALANCE" header into this method.
* Replace the existing System.out.println statements that print "BALANCE" with a call to printHeader();. Run the program.
* Change the printHeader() method to use forward slashes / instead of - characters.