To execute a task we use the task name on the command line when we run Gradle. So, if our build script contains a task with the name first, we can run the task with the following command:

$ gradle first

But, we can also define a default task or multiple default tasks that need to be executed, even if we don't explicitly set the task name. So, if we run the gradle command without arguments, the default task of our build script will be executed.

To set the default task or tasks, we use the method defaultTasks. We pass the names of the tasks that need to be executed, to the method. In the following build script, we make the tasks first and second the default tasks:

defaultTasks 'first', 'second'

task first {
    doLast {
        println "I am first"
    }
}

task second {
    doFirst {
        println "I am second"
    }
}

We can run our build script and get the following output:

$ gradle
:first
I am first
:second
I am second

BUILD SUCCESSFUL

Total time: 2.097 secs