How can I troubleshoot and resolve the issue of “dependent class becomes invalid and demands recompilation”?

In the context of Salesforce, this particular issue provided by you may occur due to changes being made to the references class which can break the structure that was expected by the dependent class. For Instance, consider a scenario where if a method signature in the referenced class is redefined or modified then it can lead to errors related to compilation in the dependent class.

Here is the example given:-

Suppose you have a class “MainClass” with a method called “process data”

Public class MainClass {
    Public void processData(String data) {
        // Some logic here
    }
}

Now if you have another class “dependent class” which has the references of “Main class” then:

Public class DependentClass {
    Private MainClass mainInstance;
    Public DependentClass() {
        mainInstance = new MainClass();
    }
    Public void performProcessing(String data) {
        mainInstance.processData(data);
    } 

}If you would modify or edit the “process data” method in “mainclass” the class whose named is “dependent class” would become invalid and would want recompilation.

Therefore, to address this type of issue you would be recommended that try to ensure that the reference class should be compatible with the dependent class. If you commit changes, then try to recompile both classes and try to ensure that any dependent classer should be adjusted accordingly to changes that have been committed in the referenced class.