Defining dependencies between tasks

Until now, we have defined tasks independent of each other. But in our projects we need dependencies between tasks. For example, a task to package compiled class files is dependent on the task to compile the class files. The build system should then first run the compile task, and when the task is finished, the package task must be executed.

In Gradle, we can add task dependencies with the dependsOn method for a task. First, let's look at a simple task dependency:

task first << { task ->
    println "Run ${task.name}"
}

task second << { task ->
    println "Run ${task.name}"
}

// Define dependency of task second on task first
second.dependsOn 'first'

Note that we define the dependency of task second on task first, in the last line. When we run the script, we see that the first task is executed before the second task:

$ gradle second
:first
Run first
:second
Run second

BUILD SUCCESSFUL

Total time: 2.145 secs

Another way to define the...