build.gradle

apply plugin: 'groovy'

repositories {
    mavenCentral()
}

dependencies {
    compile 'org.codehaus.groovy:groovy-all:2.1.6'
}

task runScript(dependsOn: 'classes', type: JavaExec) {
    description 'Run Groovy script'

    // Set main property to name of Groovy script class.
    main = 'ConvertXML2Json'

    // Set classpath for running the Groovy script.
    classpath = sourceSets.main.runtimeClasspath

    if (project.hasProperty('xml')) {
        // Pass command-line argument to script.
        args new File(".").absolutePath + File.separator + project.getProperty('xml')
    }

    if (project.hasProperty('output')) {
        // Pass output type command-line argument to script.
        args project.getProperty('output')
    }
}

defaultTasks 'runScript'