title: Show a button when with the help of gestures
body: <p>In my activity is an action button which is invisible. Now I want to display him when i tap or swipe. </p>
  
  <p>My XML file:</p>
  
  <pre><code>    &lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:scrollbars="vertical"
  android:visibility="visible"&gt;
  
  &lt;LinearLayout
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      android:orientation="vertical"
      tools:ignore="ScrollViewSize"&gt;
  
      &lt;RelativeLayout
          android:id="@+id/activity_a1"
          android:layout_width="match_parent"
          android:layout_height="625dp"
          android:background="@color/background"
          android:paddingBottom="@dimen/activity_vertical_margin"
          android:paddingLeft="@dimen/activity_horizontal_margin"
          android:paddingRight="@dimen/activity_horizontal_margin"
          android:paddingTop="@dimen/activity_vertical_margin"
          tools:context="com.thebest.charakterisierung.a1"
          tools:ignore="UselessParent"&gt;
  
  
          &lt;android.support.design.widget.FloatingActionButton
              android:id="@+id/floatingActionButton"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_alignParentEnd="true"
              android:layout_alignParentRight="true"
              android:layout_alignParentTop="true"
              android:clickable="true"
              android:visibility="inviible"
              app:backgroundTint="@android:color/holo_green_dark"
              app:fabSize="mini"
              app:srcCompat="@android:drawable/ic_menu_save" /&gt;
      &lt;/RelativeLayout&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p></p>
  
  <p>My java file:</p>
  
  <pre><code>package com.test.test;
  import android.content.SharedPreferences;
  import android.support.v4.view.GestureDetectorCompat;
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  import android.view.GestureDetector;
  import android.view.MotionEvent;
  import android.view.View;
  import android.view.WindowManager;
  import android.widget.Button;
  import android.view.MotionEvent;
  
  public class Geschichte1 extends AppCompatActivity implements                 GestureDetector.OnGestureListener, GestureDetector.OnDoubleTapListener {
  private GestureDetectorCompat GestureDetect;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      this.requestWindowFeature(android.view.Window.FEATURE_NO_TITLE);
      this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,   WindowManager.LayoutParams.FLAG_FULLSCREEN);
      this.setContentView(R.layout.activity_a1);
      Button btn =(Button)findViewById(R.id.floatingActionButton);
      GestureDetect = new GestureDetectorCompat(this, this);
      GestureDetect.setOnDoubleTapListener(this);
      }
  
  
  @Override
  public boolean onSingleTapConfirmed(MotionEvent e) {
              return false;
  }
  
  @Override
  public boolean onDoubleTap(MotionEvent e) {
      return false;
  }
  
  @Override
  public boolean onDoubleTapEvent(MotionEvent e) {
      return false;
  }
  
  @Override
  public boolean onDown(MotionEvent e) {
      return false;
  }
  
  @Override
  public void onShowPress(MotionEvent e) {
  
  }
  
  @Override
  public boolean onSingleTapUp(MotionEvent e) {
      return false;
  }
  
  @Override
  public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
      return false;
  }
  
  @Override
  public void onLongPress(MotionEvent e) {
  
  }
  
  @Override
  public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,     float velocityY) {
      return false;
  }
  </code></pre>
  
  <p>}</p>
  
  <p>Maybe I can add in java file : Button.setVisibility or Button.Visible ? Well nothing what i tried is working.</p>