问权限对话框在android中不显示。

EN

class MainActivity : AppCompatActivity(), PermissionListener {
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    choose.setOnClickListener {
        Toast.makeText(applicationContext,"HEllo",Toast.LENGTH_SHORT).show();
        Dexter.withActivity(this)
            .withPermission(android.Manifest.permission.CAMERA)
            .withListener(this)
    }
}

override fun onPermissionGranted(response: PermissionGrantedResponse?) {
    Toast.makeText(applicationContext,"Granted",Toast.LENGTH_SHORT).show();
}

override fun onPermissionRationaleShouldBeShown(
    permission: PermissionRequest?,
    token: PermissionToken?
) {

}

override fun onPermissionDenied(response: PermissionDeniedResponse?) {
    Toast.makeText(applicationContext,"Denied",Toast.LENGTH_SHORT).show();
}
}