What does UP-TO-DATE in gradle indicate?

Question

I have recently started using gradle in a project and I am running the standard

gradle clean init build

I noticed that in many of the tasks that are running, I get this UP-TO-DATE message in the console, next to the current task that's running. eg:-

:foo:bar:test UP-TO-DATE

I am curious as to what does this message mean. Couldn't find any documentation around the same.

Answer 1

Everything that Gradle does is a task. Most tasks have inputs and outputs declared. Gradle will determine if a task is up to date by checking the inputs and outputs.

For example, your compile task input is the source code. If the source code hasn't changed since the last compile, then it will check the output to make sure you haven't blown away your class files generated by the compiler. If the input and output is unchanged, it considers the task "up to date" and doesn't execute that task. This can save a lot of time, especially on large builds.

Answer 2

BTW: In case you really want to bypass this build optimization, you can use the --rerun-tasks command-line option to enforce execution of every task. see documentation of gradle command-line options

Answer 3

Gradle is an incremental build system. This means that it checks that a task must really be executed before actually executing it, in order to be faster.

So, for example, if you already compiled your source files in a previous build, and didn't modify any source file (nor any other input of the compile task), then Gradle won't recompile all the source files, because it know it will lead to exactly the same output as the one already present in the build folder. And the compilation is thus safely skipped, leading to a faster build.

More information in the documentation