Demonstrate Simple Pendulum with Android Studio

in utopian-io •  21 days ago

Repository

https://github.com/enyason/Simple_Pendulum_Demonstration

What Will I Learn?

  • How to Implement simple pendulum with android studio
  • How to create custom views
  • How to do simple animation with the canvas class

Requirements

  • System Requirements : Java JDK, Android Studio
  • OS Support for Java : Windows, mac OS, Linux
  • Required Knowledge : A fair knowledge of Java and use of Android Studio

Resources for this Tutorial

Difficulty

  • Basic

Tutorial Duration 20- 30 Minutes

Tutorial Content

In this tutorial, we are going to demonstrate the simple pendulum using android studio. The gif below demonstrate a typical simple pendulum.

What is a Pendulum?

A pendulum is a weight suspended from a pivot so that it can swing freely. For more information on simple pendulum, visit https://en.wikipedia.org/wiki/Pendulum

STEP 1 : Create a new Android Studio Project

Open android studio an create a new project and add an empty activity to it

STEP 2 : Create a Custom View for the Pendulum Implementation

To achieve this , we are going to extend the view class of the android framework

  • Extend View Class

Here we extend the view class then we implement it's constructor. See image below

public class PendulumView extends View {

   public PendulumView(Context context) {
            super(context);
            init();
            }

  public PendulumView(Context context, @Nullable AttributeSet attrs) {
            super(context, attrs);
            init();
            }

  public PendulumView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
            super(context, attrs, defStyleAttr);
            init();
            }
            
        }

STEP 3 : Override the onDraw Method of the class

All our implemtation will go to the onDraw method

  • Implement the rectangular box that serves as the holder

          ...
          pathHolder.moveTo(xCenter,100);
            pathHolder.lineTo(300,100);
    
            pathHolder.moveTo(300,100);
            pathHolder.lineTo(300,50);
    
            pathHolder.moveTo(300,50);
            pathHolder.lineTo(420,50);
    
            pathHolder.moveTo(420,50);
            pathHolder.lineTo(420,100);
    
            pathHolder.moveTo(420,100);
            pathHolder.lineTo(xCenter,100);
            
            ...
    

    complete source code

    This codes blocks basically draws a rectangular path based on the x and y points we specified. The result is seen in the image below

  • Implement the Thread

          ...
          //build path for the thread
            pathThread.moveTo(xCenter, 100);
            pathThread.lineTo((float) thread_x, 350);
            ...
    

    This code block draws the line for the thread, and its length is updated on motion.

  • Implement the circle ball

     canvas.drawCircle(circle_x, 370, 30, paintCircle);
    

    This line on code draws the circle to screen and updates its position, causing the ball to move when invalidate() is called on the ondraw method. see image below

STEP 4 : Handle Ball Direction

if (circle_x >= boundryRight) {  x_dir -= 5;}

if (circle_x <= boundryLeft) {   x_dir += 5;}

circle_x = circle_x + x_dir;
thread_x = thread_x + x_dir;

complete source code

In this step, we handle the ball direction by checking comparing its position with the specified boundary

STEP 5 : Include PendulumView as a view in the activity_main_layout

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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="match_parent"
    android:layout_height="match_parent"
    tools:context="com.nexdev.enyason.simple_pendulum_demonstration.MainActivity">

    <com.nexdev.enyason.simple_pendulum_demonstration.PendulumView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</RelativeLayout>

Code explanation

All we did here is to include the PendulumView as a view in the layout file. Below is the output of what we have done in this step

With all these steps taken, we should have something like this

Curriculum

Proof of Work The complete source code can be found on github

https://github.com/enyason/Simple_Pendulum_Demonstration

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Thank you for your contribution @ideba.
After analyzing your contribution we suggest the following:

  • In title it's important to have key words about the technology that will explain. We suggest you place this keyword in your Java JDK tutorial.

  • Code sections are better displayed using the code markup, instead of placing them as screenshots.

Good tutorial to learn how to create objects and give movement to objects in Java JDK / Android Studio.

We are waiting for more of your tutorials. Thank you again for your work!

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Thank you for your review, @portugalcoin!

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thanks for your review at @portugalcoin . I'll improve on my contribution

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