Trying to add swipe Gesture to simple app

Question

I'm trying to learn android(studio) in the hopes of creating my own apps that others will enjoy in the near future. I'm trying to write a simple gesture app where when the user swipes left or right the textView widget will change.

Thanks in advance.

This isn't working code but I think I'm in the general space of what I want to do hopefully someone can make it a little clearer What I have currently:

MainActivity.java

package com.example.chris.gestureproject;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.view.MotionEvent;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;



public class MainActivity extends AppCompatActivity implements SimpleOnGestureListener {




    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button tapButton = (Button)findViewById(R.id.tapButton);

        tapButton.setOnClickListener(
                new Button.OnClickListener(){
                    public void onClick(View v){
                        TextView messageText = (TextView)findViewById(R.id.messageText);
                        messageText.setText("I Got Tap");
                    }
                }
        );
    }

    SimpleOnGestureListener simpleOnGestureListener = new SimpleOnGestureListener() {

        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                               float velocityY) {

            float sensitvity = 50;
            if ((e1.getX() - e2.getX()) > sensitvity) {
                SwipeLeft();
            } else if ((e2.getX() - e1.getX()) > sensitvity) {
                SwipeRight();
            }

            return true;
        }

    };

    GestureDetector gestureDetector = new GestureDetector(
            simpleOnGestureListener);

    private void SwipeLeft() {

        TextView messageText = (TextView)findViewById(R.id.messageText);
        messageText.setText("Left Side Swiped");

    }


    private void SwipeRight() {

        TextView messageText = (TextView)findViewById(R.id.messageText);
        messageText.setText("Right Side Swiped");
    }



}