Monster file single-handedly implements large blocks of functionality within a system and performs multiple, non-cohesive functionalities. It violates the basic approach of structured programming which is: Break a big problem into smaller problems and then resolve these problems. The result obtained inevitably solves the big problem. The monster file typically has high LOC, high LCOM, high CC, and a higher count of functions.


  • The Monster file tends to become bulky and complex.
  • Refactoring becomes a fairly complicated task. Refactoring of such a file affects a significant part of the system, as other members of the system depend heavily on Monster File.
  • The tendency to hold too much non-cohesive functionality also means this file becomes critical; making even a small change to it has a system-wide impact in terms of testing efforts.
  • Time and maintenance cost increases.


  • The file is large and complex (high LOC and many long and complex functions).
  • Functions implement non-cohesive functionalities.


  • The file is large and complex (high LOC and too many long and complex functions).

Functions implement non-cohesive functionalities.

BankAccount.js {
let acInfo = [];
// Cohesive methods
public void openAccount();
public void closeAccount();
// Non-cohesive method (should ideally exist in Customer class)
public void createCustomer();

File excessively accesses data of other files and also tends to implement logic that belongs to those files.

//File BankAccount accesses attributes of AccountInfo file
// File also implements logic that should belong to AccountInfo file.
public boolean isAccountValid{ 
  if( (acInfo.isActive) && (acInfo.balance > acInfo.minimumBalance ) { 
    return true; 
  } return false; 

Solution: Move the logic into a method in the AccountInfo file and invoke that function.

public boolean isAccountValid() {
return acInfo.isAccountValid();


  • Follow the ‘one file one task’ rule. Distribute the system intelligence across several files and let one file handle only one task. Collectively they will solve the intended problem.
  • Functionalities that have common, overlapping aspects but are also dissimilar in other aspects can be implemented as sibling files and the common functionality can be moved into a third file.
  • If distinct groups of data-operations exist in one file, try extracting them into separate files.
  • Make sure that file functions are not too long and do not use more than necessary data from other files.
  • The monster file is often a result of incrementally adding functionality to an existing file over time. This should be avoided. Try refactoring the file occasionally. Split the file instead of adding new functionality.