Place Literals on the Left

When comparing literals in a statement, when possible always place the already defined variable on the left of the expression.

Firstly, this ensures that no NullPointerException's will be thrown by definition.

class ComparisonTest {
    
    private static final String CODE = "123"; 
    
    public void compareValues(String valueToCompare) {
        // valueToCompare in this case could be undefined and throw a NullPointerException
        if (valueToCompare.equals(CODE)) {
            ... do something
        }
        
        // No NullPointerException will be thrown in this case
        if (CODE.equals(valueToCompare)) {
            ... do something
        }
    }
}

Secondly, this also aids in removing any potential mistaken assignments.

if (variable = 5) {...} // Compiles and will assign variable
if (5 = variable) {...} // Won't compile - potentially catching a mistake
if (5 == variable) {...} // Compiles