Gradle - How to get task output from subproject

I'm new to Gradle. I have a sample project structure like this:

rootA/
├── build.gradle
├── settings.gradle
└── subA
    └── build.gradle

In subA project, there is a task, let call, goInsideSubA() and this task can return a string (something like) "this is inside subA project"

Here is my sample context:

//subA/build.gradle:

task goInsideSubA() {
    def string = "this is inside subA project"
}

// rootA/build.gradle

task showInsideSubA() {
    doLast {
        // how can I get the string from :subA:goInsideSubA task here
    }
}

// settings.gradle

include ':subA'

My question is how can I get that string "this is inside subA project" for the task showInsideSubA() in rootA project to reuse?

I found a solution, by using "task properties":

//subA/build.gradle:

task goInsideSubA() {
    ext {
        myString = "this is inside subA project"
    }
}

// rootA/build.gradle

task showInsideSubA() {
    doLast {
        println tasks.getByPath(':subA:goInsideSubA').myString
    }
}

// settings.gradle

include ':subA'

result:

$ gradle -q showInsideSubA
> this is inside subA project