Lesson 3A Kahve Sipariş Uygulaması

 XML 

<?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:id="@+id/activity_main"    android:layout_width="match_parent"    android:layout_height="match_parent"    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.ersanaskin.notopening.MainActivity"    android:orientation="vertical">
    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="TOPPINGS" />    <LinearLayout        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginTop="15dp">        <CheckBox            android:text="CheckBox"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/checkBox"            android:layout_weight="1"            android:layout_marginRight="30dp"/>        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="Whipped Cream" />    </LinearLayout>    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="QUANTITY"        android:layout_marginTop="20dp"/>    <LinearLayout        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginTop="15dp">        <Button            android:layout_width="50dp"            android:layout_height="wrap_content"            android:text="-"            android:onClick="decreaseQuantity"/>        <TextView            android:id="@+id/quantity_text_view"            android:layout_width="50dp"            android:layout_height="wrap_content"            android:text="0"            android:textAlignment="center"/>        <Button            android:layout_width="50dp"            android:layout_height="wrap_content"            android:text="+"            android:onClick="increaseQuantity"/>    </LinearLayout>    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="ORDER SUMMARY"        android:layout_marginTop="15dp"/>    <TextView        android:id="@+id/order_summary_text_view"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginTop="15dp"/>    <Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="ORDER"        android:onClick="displayMessage"/></LinearLayout>

JAVA

package com.example.ersanaskin.notopening;
import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.TextView;
public class MainActivity extends AppCompatActivity {

    int quantity = 0;    int coffeePrice = 10;
    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    }

    public void increaseQuantity(View view){
        quantity ++;        display(quantity);    }

    public void decreaseQuantity(View view){
        quantity --;        display(quantity);    }

    private void display(int number) {
        TextView quantityTextView = (TextView) findViewById(R.id.quantity_text_view);        quantityTextView.setText("" + number);    }

    public void displayMessage(View v) {
        String message = "Hello Ersan. You bought " + quantity + " coffee. Please pay $" + quantity * coffeePrice + ".";        TextView orderSummaryTextView = (TextView) findViewById(R.id.order_summary_text_view);        orderSummaryTextView.setText(message);    }
}