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This Notes is according to the udacity free course :

Android Development for Beginners

Lesson 2B : Final version code

	package com.example.android.justjava;
	import android.os.Bundle;
	import android.support.v7.app.ActionBarActivity;
	import android.view.View;
	import android.widget.TextView;
	import java.text.NumberFormat;
	/**
	* This app displays an order form to order coffee.
	*/
	public class MainActivity extends ActionBarActivity {
	int quantity = 1;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_main);
	}
	/**
	* This method is called when the order button is clicked.
	*/
	public void submitOrder(View view) {
	int price = quantity * 5;
	String priceMessage = price + " dollars for " + quantity + " cups of coffees. Pay up";
	priceMessage = priceMessage + "\nThank You";
	displayPrice(price);
	displayMessage(priceMessage);
	}
	/**
	* This method is called when the increment button is clicked.
	*/
	public void increment(View view) {
	quantity = quantity + 1;
	display(quantity);
	}
	/**
	* This method is called when the decrement button is clicked.
	*/
	public void decrement(View view) {
	quantity = quantity - 1;
	display(quantity);
	}
	/**
	* This method displays the given quantity value on the screen.
	*/
	private void display(int number) {
	TextView quantityTextView = (TextView) findViewById(
	R.id.quantity_text_view);
	quantityTextView.setText("" + number);
	}
	/**
	* This method displays the given price on the screen.
	*/
	private void displayPrice(int number) {
	TextView priceTextView = (TextView) findViewById(R.id.price_text_view);
	priceTextView.setText(NumberFormat.getCurrencyInstance().format(number));
	}
	/**
	* This method displays the given text on the screen.
	*/
	private void displayMessage(String message) {
	TextView priceTextView = (TextView) findViewById(R.id.price_text_view);
	priceTextView.setText(message);
	}
	}

view raw JustJava_final_version.java hosted with ❤ by GitHub

	<?xml version="1.0" encoding="utf-8"?>
	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
	xmlns:tools="http://schemas.android.com/tools"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	android:orientation="vertical"
	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.example.android.justjava.MainActivity">
	<TextView
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_marginBottom="16dp"
	android:text="Quantity"
	android:textAllCaps="true" />
	<LinearLayout
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:orientation="horizontal"
	android:layout_marginBottom="16dp">
	<Button
	android:layout_width="48dp"
	android:layout_height="48dp"
	android:onClick="decrement"
	android:text="-" />
	<TextView
	android:id="@+id/quantity_text_view"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:paddingLeft="8dp"
	android:paddingRight="8dp"
	android:text="1"
	android:textColor="@android:color/black"
	android:textSize="16sp" />
	<Button
	android:layout_width="48dp"
	android:layout_height="48dp"
	android:onClick="increment"
	android:text="+" />
	</LinearLayout>
	<TextView
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_marginBottom="16dp"
	android:text="Price"
	android:textAllCaps="true" />
	<TextView
	android:id="@+id/price_text_view"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_marginBottom="16dp"
	android:text="$5 "
	android:textColor="@android:color/black"
	android:textSize="16sp" />
	<Button
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:onClick="submitOrder"
	android:text="order" />
	</LinearLayout>

view raw JustJava_final_version.xml hosted with ❤ by GitHub