Refactoring

💡 Improving code structure can have many secondary benefits: e.g.

• hidden bugs become easier to spot
• improve performance (sometimes, simpler code runs faster than complex code because simpler code is easier for the compiler to optimize).

Refactoring Name: Consolidate Duplicate Conditional Fragments

Situation: The same fragment of code is in all branches of a conditional expression.

Method: Move it outside of the expression.

Example:

if (isSpecialDeal()) {
    total = price * 0.95;
    send();
} else {
    total = price * 0.98;
    send();
}

⤵️

if (isSpecialDeal()){
    total = price * 0.95;
} else {
    total = price * 0.98;
}
send();

Refactoring Name: Extract Method

Situation: You have a code fragment that can be grouped together.

Method: Turn the fragment into a method whose name explains the purpose of the method.

Example:

void printOwing() {
    printBanner();

    //print details
    System.out.println("name:	" + name);
    System.out.println("amount	" + getOutstanding());
}

⤵️

void printOwing() {
    printBanner();
    printDetails(getOutstanding());
}

void printDetails (double outstanding) {
    System.out.println("name:	" + name);
    System.out.println("amount	" + outstanding);
}

💡 Some IDEs have built in support for basic refactorings such as automatically renaming a variable/method/class in all places it has been used.

Important: Refactoring, even if done with the aid of an IDE, may still result in regressions. Therefore, each small refactoring should be followed by regression testing.