Do you check for the presence of all necessary components or data in the system before starting work?

Yes, checking for the presence of all necessary components or data before starting work is a good practice that helps avoid errors during program execution. For example, in Java, you can verify that all required objects and resources are initialized, files are accessible, and external services are operational before proceeding.

An example of checking a file before reading:

File file = new File("data.txt");
if (!file.exists() || !file.canRead()) {
    throw new IllegalStateException("Required file is not accessible for reading");
}
// Continue working with the file

Such a check helps identify problems early and makes the program more robust.