User-defined methods in Java execute under what condition?

User-defined methods in Java are designed to execute only when they are explicitly called from another part of the program. This means that the method will not run until the program encounters a call to it, such as through function invocation with the method name and any necessary parameters.

The concept of calling methods is fundamental in Java programming because it allows programmers to organize tasks and functionality into reusable blocks of code. This approach enables better code maintenance and readability, as well as the ability to execute specific tasks based on certain conditions or user interactions.

While methods can have a return type specified, that detail is not what dictates when they execute. The main method serves as the entry point of the program, but it does not automatically invoke all user-defined methods unless they are explicitly called within it or from other methods invoked by it. Therefore, thinking of user-defined methods executing automatically or after the main method misunderstands how methods are structured and invoked in Java.