This is a small App that can be used to order coffee. It is very basic, you can order only one type of coffee which costs 5 euros per cup. It implements a quantity picker and an order button that calculates the total price of the order. The user then is prompted to send the order via email.
A Greek translation of the App is provided.
This was made for the Google Developer Challenge 2017-2018 as an assignment to practice with Java.
This is how the App behaves:(short video on Youtube)
This is what the UI looks like on my device (Lenovo tablet Lollipop API22)
Portrait
Landscape
And here is what the layout xml code looks like (file app/src/main/res/layout/activity_main.xml, or https://github.com/elisavetTriant/JustJava/blob/master/app/src/main/res/layout/activity_main.xml):
<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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:fillViewport="true"
tools:context="com.example.android.justjava.MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="@dimen/elements_margin"
android:orientation="vertical">
<EditText
android:id="@+id/name_edit_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="@dimen/elements_margin"
android:hint="@string/name"
android:textSize="@dimen/elements_text_size" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="@dimen/elements_margin"
android:text="@string/toppings"
android:textAllCaps="true"
android:textSize="@dimen/elements_text_size" />
<CheckBox
android:id="@+id/whipped_cream_checkbox"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="@dimen/elements_margin"
android:paddingLeft="@dimen/checkboxes_padding"
android:text="@string/whipped_cream"
android:textSize="@dimen/elements_text_size" />
<CheckBox
android:id="@+id/chocolate_checkbox"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="@dimen/elements_margin"
android:paddingLeft="@dimen/checkboxes_padding"
android:text="@string/chocolate"
android:textSize="@dimen/elements_text_size" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="@dimen/elements_margin"
android:text="@string/quantity"
android:textAllCaps="true"
android:textSize="@dimen/elements_text_size" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/quantity_decrement_button"
android:layout_width="@dimen/quantity_buttons_size"
android:layout_height="@dimen/quantity_buttons_size"
android:onClick="decrement"
android:text="@string/minus"
style="@style/buttonsStyle"/>
<TextView
android:id="@+id/quantity_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="@dimen/quantity_buttons_padding"
android:paddingRight="@dimen/quantity_buttons_padding"
android:textColor="@android:color/black" />
<Button
android:id="@+id/quantity_increment_button"
android:layout_width="@dimen/quantity_buttons_size"
android:layout_height="@dimen/quantity_buttons_size"
android:onClick="increment"
android:text="@string/plus"
style="@style/buttonsStyle"
/>
</LinearLayout>
<Button
android:id="@+id/order_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="@dimen/elements_margin"
android:onClick="submitOrder"
android:padding="@dimen/order_button_padding"
android:text="@string/order"
style="@style/buttonsStyle"/>
</LinearLayout>
</ScrollView>Don't forget to take a look at the resources folder ( /app/res/values ) and take a look at the code there also. For instance the styles.xml code looks like this:
<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
</style>
<style name="buttonsStyle">
<item name="android:background">@color/colorPrimary</item>
<item name="android:textColor">@android:color/white</item>
</style>
</resources>The java code looks like this (app/src/main/java/com/example/android/justjava) or https://github.com/elisavetTriant/JustJava/blob/master/app/src/main/java/com/example/android/justjava/MainActivity.java
/**
* IMPORTANT: Make sure you are using the correct package name.
* This example uses the package name:
* package com.example.android.justjava
* If you get an error when copying this code into Android studio, update it to match the package name found
* in the project's AndroidManifest.xml file.
**/
package com.example.android.justjava;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.text.NumberFormat;
/**
* This app displays an order form to order coffee.
*/
public class MainActivity extends AppCompatActivity {
//Declare and Initialise Global Vars
public int quantity = 1;
//Declare and Initialise Constants
static final int PRICE_PER_CUP = 5;
static final int CHOCOLATE_PRICE = 2;
static final int WHIPPED_CREAM_PRICE = 1;
//String constants for keys
static final String QUANTITY_KEY = "quantity";
//UI object vars
TextView quantityTextView;
CheckBox whippedCreamCheckBox;
CheckBox chocolateCheckBox;
EditText nameEditText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Get the view objects using the view IDs
quantityTextView = (TextView) findViewById(R.id.quantity_text_view);
whippedCreamCheckBox = (CheckBox) findViewById(R.id.whipped_cream_checkbox);
chocolateCheckBox = (CheckBox) findViewById(R.id.chocolate_checkbox);
nameEditText = (EditText) findViewById(R.id.name_edit_text);
updateUIValues();
}
// https://stackoverflow.com/questions/151777/saving-android-activity-state-using-save-instance-state
//prevent the application from restarting when changing orientation. Saving global vars between activity states.
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
// Save UI state changes to the savedInstanceState.
// This bundle will be passed to onCreate if the process is
// killed and restarted.
savedInstanceState.putInt(QUANTITY_KEY, quantity);
}
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
quantity = savedInstanceState.getInt(QUANTITY_KEY);
updateUIValues();
}
/**
* This method is called when the quantity increment button is clicked.
*/
public void increment(View view) {
if (quantity < 100) {
quantity = quantity + 1;
displayQuantity(quantity);
} else {
displayToastMessage(getString(R.string.max_order));
}
}
/**
* This method is called when the quantity decrement button is clicked.
*/
public void decrement(View view) {
// You can order one or more coffees!
if (quantity > 1) {
quantity = quantity - 1;
displayQuantity(quantity);
} else {
displayToastMessage(getString(R.string.min_order));
}
}
/**
* This method is called when the order button is clicked.
*/
public void submitOrder(View view) {
String orderMessage = prepareOrderMessage();
String subjectLine = getString(R.string.order_summary_email_subject, nameEditText.getText().toString());
composeEmail(subjectLine, orderMessage);
}
/**
* This method displays the given quantity value on the screen.
*/
public void displayQuantity(int number) {
quantityTextView.setText(String.valueOf(number));
}
/**
* This method, when called, updates all the TextViews dynamically with the current global vars values
*/
public void updateUIValues() {
displayQuantity(quantity);
}
/**
* This method starts an Activity to send email with the order
* More on https://developer.android.com/guide/components/intents-common.html#Email
* @param subject
* @param emailBody
*/
private void composeEmail(String subject, String emailBody) {
Intent intent = new Intent(Intent.ACTION_SENDTO);
intent.setData(Uri.parse("mailto:")); // only email apps should handle this
intent.putExtra(Intent.EXTRA_SUBJECT, subject);
intent.putExtra(Intent.EXTRA_TEXT, emailBody);
if (intent.resolveActivity(getPackageManager()) != null) {
startActivity(intent);
}
}
/**
* Create summary of the order.
*
* @param name
* @param totalPrice
* @param hasWhippedCream is whether or not the user wants whipped cream topping
* @param hasChocolate is whether or not the user wants chocolate topping
* @return text summary
*/
private String createOrderSummary(String name, int totalPrice, boolean hasWhippedCream, boolean hasChocolate) {
String priceMessage = getString(R.string.order_summary_name, name);
priceMessage += "\n" + getString(R.string.order_summary_whipped_cream, hasWhippedCream);
priceMessage += "\n" + getString(R.string.order_summary_chocolate,hasChocolate);
priceMessage += "\n" + getString(R.string.order_summary_quantity, quantity) ;
priceMessage += "\n" + getString(R.string.order_summary_price, NumberFormat.getCurrencyInstance().format(totalPrice));
priceMessage += "\n" + getString(R.string.thank_you);
return priceMessage;
}
/**
* Calculates the price of the order.
*
* @return total price of the order
*/
private int calculatePrice() {
int totalPricePerCup = PRICE_PER_CUP;
if (whippedCreamCheckBox.isChecked()){
totalPricePerCup += WHIPPED_CREAM_PRICE;
}
if (chocolateCheckBox.isChecked()){
totalPricePerCup += CHOCOLATE_PRICE;
}
return quantity * totalPricePerCup;
}
/**
* Gets values and calls createOrderSummary method.
*
* @return Order Summary String
*/
private String prepareOrderMessage(){
int totalPrice = calculatePrice();
String customerName = nameEditText.getText().toString();
boolean isWhippedCreamChecked = whippedCreamCheckBox.isChecked();
boolean isChocolateChecked = chocolateCheckBox.isChecked();
return createOrderSummary(customerName, totalPrice, isWhippedCreamChecked, isChocolateChecked);
}
/**
* This method displays a Toast Message when called.
*
* @param message, the message to be displayed
*
*/
//https://developer.android.com/guide/topics/ui/notifiers/toasts.html
private void displayToastMessage(String message){
Context context = getApplicationContext();
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, message, duration);
toast.show();
}
}