CH 6 iOS

Here is my UIViewController class:

//

//  ViewController.swift

//  CH6Ex1Circle

//

//  Created by stu2017 on 10/24/17.

//  Copyright © 2017 stu2017. All rights reserved.

//

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var tbRad: UITextField!

    @IBOutlet weak var lblCirc: UILabel!

    @IBOutlet weak var lblArea: UILabel!

    override func viewDidLoad() {

        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

    @IBAction func btnCalc(_ sender: UIButton) {

        let rad=Double(tbRad.text!);

        let circ1=Circle(radius:rad!);

        let a=String(format: "%.2f", circ1.getArea());

        let c=String(format: "%.2f", circ1.getCircumference());

        lblArea.text="Area: \(a)";

        lblCirc.text="Circumfrence: \(c)";

    }

}

 Here is my circle class

//

//  Circle.swift

//  CH6Ex1Circle

//

//  Created by stu2017 on 10/24/17.

//  Copyright © 2017 stu2017. All rights reserved.

//

import Foundation

class Circle {

    var radius = 0.0

    

    init(radius: Double) { // Constructor

        self.radius = radius

        

    }

    var Area: Double{

        return 3.14*(radius*radius)

    }

    

    func getArea() -> Double {

        return 3.14*(radius*radius)

    }

    

    var Circumference: Double {

        return 2*3.14*radius

    }

    func getCircumference() -> Double{

        return 2*3.14*radius

    }

}

Week 4 AppInventor

Hello World

SMS/Location

Circle App

Unit 5 Chapter 3Android Intro Hello World Button

package com.example.hellobuttonweek5;//this line is unique to your app
import androidx.appcompat.app.AppCompatActivity;

import android.content.res.Resources;
import android.os.Bundle;

import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

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

    }

    private void initButton() {
        Resources res= getResources();
        Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                EditText firstName = (EditText) findViewById(R.id.editTextTextPersonName);
                TextView textView = (TextView) findViewById(R.id.textView);
                String displayString=res.getString(R.string.hello,firstName.getText().toString());
                textView.setText(displayString);
            }
        });
    }

    private void initButtonClear() {
        Button clear = (Button) findViewById(R.id.button2);
        clear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                EditText firstName = (EditText) findViewById(R.id.editTextTextPersonName);
                TextView textView = (TextView) findViewById(R.id.textView);
                textView.setText("Hello World!");
                firstName.setText("");
            }
        });

    }
}

Update 9/20/2021:

If you are on the latest version of Android Studio (Android Studio Arctic Fox Version 2020.3.1) and you are on JAVA version 11 or early you may get the following error when executing your (Newly created) Android application:

> Failed to apply plugin 'com.android.internal.application'.
   > Android Gradle plugin requires Java 11 to run. You are currently using Java 1.8.
     You can try some of the following options:
       - changing the IDE settings.
       - changing the JAVA_HOME environment variable.
       - changing `org.gradle.java.home` in `gradle.properties`.

SOLUTION:Make sure you load Java11 or later (I have version 15) -

Open the Project get to Files->Settings->Build,Execution,Deployment->Build Tools->Gradle-> Use the drop down for Gradle JDK on that page and select a Java version 11 or later (Which you may have just loaded). I picked JDK 15.

  

Cross Platform Web: HelloWorld and CH8Ex1CircleWeb

CrossPlatform Hello World

Ch8Ex1CircleWeb

Swift: demo

Here is the workaround using repl.it
Circle on Repl.it
This is for use on iOS using XCode

---

// Declare our new Circle class
class Circle {
    var radius = 0.0
    
    init(radius: Double) { // Constructor
        self.radius = radius
        
    }
    var Area: Double{
        return 3.14*(radius*radius)
    }
    
    func getArea() -> Double {
        return 3.14*(radius*radius)
    }
    
    var Circumference: Double {
        return 2*3.14*radius
    }
    func getCircumference() -> Double{
        return 2*3.14*radius
    }
}



@IBAction func btnCalc(_ sender: UIButton) {

        let rad=Double(tbRad.text!);

        let circ1=Circle(radius:rad!);

        let a=String(format: "%.2f",circ1.getArea());

        let c=circ1.getCircumference();

        lblArea.text="Area: \(a)";

        lblCirc.text="Circumfrence: \(c)";

    }

Xamarin Intro: Hello World

 1) Open MS Visual Studio 2019

2) File-> New Project->C#->Android->Android App (Xamarin) Blank App (
3) Launch the app
You can run the app on your android phone via usb cable
or
Open Android Studio and launch the emulator.
Now you will see that emulator on the Start arrow:

4) Now modify the ui that was created, first stop the app (red square button)
Goto Resources->Layout->Main.axml
- Add a linear (vertical) layout to replay the Relative Layout (see the xml below)
- Add a TextView
- Add a EditView
- Add a button
5) Goto Mainactivity.cs
add code like this after line 17:
            Button button = FindViewById<Button>(Resource.Id.button1);

            TextView tvResult = FindViewById<TextView>(Resource.Id.textView1);

            EditText etName = FindViewById<EditText>(Resource.Id.editText1);

            button.Click += delegate {

                tvResult.Text = "Hello " + etName.Text;

            };

My activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:orientation="vertical"

    android:layout_width="match_parent"

    android:layout_height="match_parent">

    <Button

        android:id="@+id/button1"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="Click Me" />

    <EditText

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:minWidth="25px"

        android:minHeight="25px"

        android:id="@+id/editText1"

        android:hint="Your Name" />

    <TextView

        android:textAppearance="?android:attr/textAppearanceMedium"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/textView1" />

</LinearLayout>

MS Visual Studio 2019 Xamarin: How To on Android

Note: The emulator requires that you have an Intel CPU on your workstation.

1) Open MS Visual Studio 2019
2) File-> New Project->C#->Android->Android App (Xamarin) Blank App 

3) In MainActivity.cs

- on line 6 insert

using System;

using Android.Widget; //if not already there

4) Launch the app
You can run the app on your android phone via usb cable
or
Open Android Studio and launch the emulator.
Now you will see that emulator on the Start arrow:

5) Now modify the ui that was created, first stop the app (red square button)
Goto Resources->Layout->Main.axml

- Delete the relative layout.
- Add a linear (vertical) layout (see the xml below)
- Add a TextView
- Add a EditView
- Add a button

  6) Add the Circle class Right Click on the project->New C# Class named Circle.
public class Circle
    {
        private double radius;

        public double Radius
        {
            get
            {
                return radius;
            }
            set
            {
                radius = value;
                if (radius < 0)
                    radius = radius * -1;
            }
        }

        public Circle(double radius)
        {
            this.radius = radius;
        }

        public double getArea()
        {
            return Math.PI * radius * radius;
        }

        public double getCircumference()
        {
            return 2 * Math.PI * radius;
        }
    }

7) Goto Mainactivity.cs

after line 17// SetContentView(Resource.Layout.activity_main);
add code like this: 
Button button = FindViewById<Button>(Resource.Id.button1);
TextView tvResult = FindViewById<TextView>(Resource.Id.textView1);
EditText etRadius = FindViewById<EditText>(Resource.Id.editText1);

button.Click += delegate {
  Circle myCircle = new Circle(Double.Parse(etRadius.Text));

  tvResult.Text = "Area: " + String.Format("{0:0.00}", myCircle.getArea());

  tvResult.Text +="\nCircumference: "+String.Format("{0:0.00}", myCircle.getCircumference());

};

8) You will see this error: The name 'Double' does not exist in the current context
Click on the light bulb and it will add:
using System;

9) If you can not run an emulator and have an android phone:
Get the .apk from here \bin\Debug
Copy it to your phone and install it.

Note see below for a LinearLayout example.
//activity_main.xml
<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:orientation="vertical"

    android:layout_width="match_parent"

    android:layout_height="match_parent">

    <Button

        android:id="@+id/button1"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="Calc" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:minWidth="25px"
        android:minHeight="25px"
        android:id="@+id/editText1"
        android:hint="Radius" />

    <TextView

        android:textAppearance="?android:attr/textAppearanceMedium"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/textView1" />

</LinearLayout>