Is It a Bad Practice to Declare Constructors Before Class Variables in Java?

What are the best practices for declaring constructors and variables in a Java class?

public class Example {
    private int number;  // Variable declaration

    public Example(int number) { // Constructor declaration
        this.number = number;
    }
}

In Java, the order of declaring class variables and constructors does not affect the functionality of the code, as long as the variables are not used before they are initialized. However, there are best practices to enhance code readability and maintainability.

public class Sample {
    private String name; // Variable declared first
    private int age;

    // Constructor declared afterwards
    public Sample(String name, int age) {
        this.name = name;
        this.age = age;
    }
}

Causes

• Code readability may decrease if constructors are placed before variables, making it harder for developers to quickly understand class structure.
• Following consistent conventions makes it easier for new developers to join the project.

Solutions

• Declare variables at the beginning of the class to promote better readability.
• Include documentation or comments above your constructors explaining their purpose.

Mistake: Placing the constructor before the variable declaration, causing confusion about property initialization.

Solution: Always declare class variables at the top for clarity.

Mistake: Not following a consistent ordering scheme in large classes leading to messy code.

Solution: Establish a team style guide that specifies the order of declarations.