Kotlin companion object

companion object 修饰为伴生对象，伴生对象在类中只能存在一个，类似于java中的静态方法 Java 中使用类访问静态成员，静态方法。

companion object {
    private const val TAG = "MainActivity"
    private const val REQUEST_SEARCH = 10000
    fun actionStart(activity: Activity) {
        val intent = Intent(activity, MainActivity::class.java)
        activity.startActivity(intent)
    }
}