AndroidJavaClass unityPlayer=new AndroidJavaClass("com.unity3d.player.UnityPlayer");

AndroidJavaObject currentActivity=unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");

AndroidJavaClass toast=new AndroidJavaClass("android.widget.Toast");

AndroidJavaObject context=currentActivity.Call<AndroidjavaObject>("getApplicationContext");

currentActivity.Call("runOnUiThread",new AndroidJavaRunnable(()=>{

tocsat.CallStatic<AndroidJavaObject>("makeText",context,"send...",tocast.GetStatic<int>("LENGTH_LONG")).Call("show");

}));