Beginner's Android App Development - Simplest Price Comparison

This post is a summary of my 1st Android App. This App allows its user to enter the price and quantity per package (bag, can, pound, kg, inch, meter, etc.) of a product and calculate and keep the unit price in a list for easy comparison. I developed this App to help me find the product with the lowest unit price when I face similar products of different quantity and price.

Sample Screen Shots

Source Code

MainActivity.java

package com.whhuang.simplest_price_comparison; import android.app.Activity; import android.app.AlertDialog; import android.os.Bundle; import android.text.Html; import android.text.method.LinkMovementMethod; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.LinearLayout; import android.widget.TextView; import android.widget.Toast; import com.whhuang.simplest_price_comparison.MainActivity; import com.whhuang.simplest_price_compare.R; public class MainActivity extends Activity { EditText amount1; EditText amount2; EditText amount3; Button calbutton, clearonebutton, clearallbutton; double x = 0; double x1 = 0; double y = 0; double z = 0; int i = 0; protected static final int MENU_ABOUT = Menu.FIRST; protected static final int MENU_QUIT = Menu.FIRST+1; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main_add_header); initControls(); } @Override public boolean onCreateOptionsMenu(Menu menu){ super.onCreateOptionsMenu(menu); menu.add(0, MENU_ABOUT, 0, "About..."); menu.add(0, MENU_QUIT, 0, "Quit"); return true; } @Override public boolean onOptionsItemSelected(MenuItem item){ super.onOptionsItemSelected(item); switch(item.getItemId()){ case MENU_ABOUT: openOptionsDialog(); break; case MENU_QUIT: finish(); break; } return true; } private void openOptionsDialog() { AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this); dialog.setTitle("About Easy Price Comparision"); LayoutInflater inflater = (LayoutInflater) this.getSystemService(LAYOUT_INFLATER_SERVICE); View layout = inflater.inflate(R.layout.about, null); TextView text = (TextView) layout.findViewById(R.id.text); text.setMovementMethod(LinkMovementMethod.getInstance()); text.setText(Html.fromHtml("<p>Created by Wei-Hsiung Huang on Oct. 26, 2014. " + "Please send comment / suggestion to wei48221@gmail.com.</p>" + "<p>I am a 1st year student at Bethel School of Supernatural Ministry (BSSM) in Redding, CA. " + "I am raising fund for mission trip to Slovakia (2015/3/18 ~ 2015/3/30). " + "If you would like to make donation to support my mission trip, please visit the below website.</p>" + "<a href=https://trips.ibethel.org/transactions/new/6935> https://trips.ibethel.org/transactions/new/6935</a")); dialog.setView(layout); AlertDialog alert = dialog.show(); } private void initControls() { amount1 = (EditText)findViewById(R.id.qty); amount2 = (EditText)findViewById(R.id.price); amount3 = (EditText)findViewById(R.id.pack); amount1.setText(""); amount2.setText(""); amount3.setText("1"); calbutton = (Button)findViewById(R.id.cal); calbutton.setOnClickListener(new Button.OnClickListener() {public void onClick (View v) {calculate();}}); clearonebutton = (Button)findViewById(R.id.clearone); clearonebutton.setOnClickListener(new Button.OnClickListener() {public void onClick (View v) {clearone();}}); clearallbutton = (Button)findViewById(R.id.clearall); clearallbutton.setOnClickListener(new Button.OnClickListener() {public void onClick (View v) {clearlist();}}); } private void clearone() { if (i > 0) { Toast.makeText(this, "Clear Last Item", Toast.LENGTH_SHORT).show(); final LinearLayout lo = (LinearLayout)findViewById(R.id.linearMain); lo.removeViewAt(i-1); i = i - 1; } else { Toast.makeText(this, "List Is Empty", Toast.LENGTH_SHORT).show(); } } private void clearlist() { if (i > 0) { Toast.makeText(this, "Clear All Item(s)", Toast.LENGTH_SHORT).show(); final LinearLayout lc = (LinearLayout)findViewById(R.id.linearMain); lc.removeAllViews(); i = 0; } else { Toast.makeText(this, "List Is Empty", Toast.LENGTH_SHORT).show(); } } private void calculate() { if (amount1.getText().toString().equals("")) {amount1.setText("0");} x = Double.parseDouble(amount1.getText().toString()); if (amount2.getText().toString().equals("")) {amount2.setText("0");} y = Double.parseDouble(amount2.getText().toString()); x1 = Double.parseDouble(amount3.getText().toString()); if (x != 0 && y != 0 && x1 != 0){ z = y / (x * x1); i = i + 1; final LinearLayout lm = (LinearLayout)findViewById(R.id.linearMain); LinearLayout ll = new LinearLayout(this); ll.setOrientation(LinearLayout.HORIZONTAL); TextView product = new TextView(this); product.setText("Item-" + i + " , "); ll.addView(product); TextView price = new TextView(this); price.setText("Price: " + y + " , "); ll.addView(price); TextView qty = new TextView(this); qty.setText("Total Qty.: " + (x * x1) + " , "); ll.addView(qty); TextView up = new TextView(this); up.setText(String.format("U/P: %.2f", z)); ll.addView(up); lm.addView(ll); } else { Toast.makeText(this, "Price, Qty. & Pack Must Be Greater Than 0", Toast.LENGTH_SHORT).show(); } amount1.setText(""); amount2.setText(""); amount3.setText("1"); amount2.requestFocus(); } }

Layout

activity_main_add_header.xml

<relativelayout 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: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.whhuang.simplest_price_comparison.MainActivity" > <!-- Header aligned to top --> <RelativeLayout android:id="@+id/header" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:gravity="bottom" > <TextView android:id="@+id/pricetxt" android:layout_width="wrap_content" android:layout_height="32dp" android:gravity="bottom" android:text="Price: " android:textSize="20sp" /> <EditText android:id="@+id/price" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_above="@+id/qtytxt" android:layout_margin="0dp" android:layout_toRightOf="@+id/pricetxt" android:gravity="center_horizontal" android:hint="0.00" android:inputType="numberDecimal" android:padding="10dip" android:textSize="12sp" /> <TextView android:id="@+id/qtytxt" android:layout_width="wrap_content" android:layout_height="32dp" android:layout_below="@+id/pricetxt" android:gravity="bottom" android:text="Quantity Per Pack: " android:textSize="20sp" /> <EditText android:id="@+id/qty" android:layout_width="62dp" android:layout_height="wrap_content" android:layout_alignBottom="@+id/qtytxt" android:layout_alignTop="@+id/qtytxt" android:layout_margin="0dp" android:layout_toRightOf="@+id/qtytxt" android:gravity="center_horizontal" android:hint="0.00" android:inputType="numberDecimal" android:padding="10dp" android:textSize="12sp" /> <TextView android:id="@+id/packtxt" android:layout_width="wrap_content" android:layout_height="32dp" android:layout_below="@+id/qtytxt" android:gravity="bottom" android:text="No. of Pack: " android:textSize="20sp" /> <EditText android:id="@+id/pack" android:layout_width="62dp" android:layout_height="wrap_content" android:layout_alignBottom="@+id/packtxt" android:layout_alignTop="@+id/packtxt" android:layout_margin="0dp" android:layout_toRightOf="@+id/packtxt" android:gravity="center_horizontal" android:hint="0.00" android:inputType="numberDecimal" android:padding="10dp" android:textSize="12sp" /> <Button android:id="@+id/cal" android:layout_width="wrap_content" android:layout_height="90dp" android:layout_alignParentRight="true" android:text="Calculate" /> <View android:id="@+id/view" android:layout_width="match_parent" android:layout_height="2dp" android:layout_below="@+id/packtxt" android:background="#000000" /> </RelativeLayout> <!-- Footer aligned to bottom --> <linearlayout android:id="@+id/footer" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true"> <Button android:id="@+id/clearone" android:layout_width="0px" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_weight="1" android:text="Clear Last Item" /> <Button android:id="@+id/clearall" android:layout_width="0px" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_weight="1" android:text="Clear All Item" /> </LinearLayout> <!-- Scrollable items below header --> <scrollview android:id="@+id/scrollableContents" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_below="@id/header" android:layout_above="@id/footer"> <!-- android:background="#005" --> <linearlayout android:layout_width="match_parent" android:layout_height="25dp" android:orientation="vertical" android:id="@+id/linearMain"> </LinearLayout> </ScrollView> </RelativeLayout>

about.xml

<?xml version="1.0" encoding="utf-8"?><linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/layout_root" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="fill_parent" android:padding="10dp" > <textview android:id="@+id/text" android:layout_width="wrap_content" android:layout_height="fill_parent" android:textColor="#ff000000" /> </LinearLayout>

Manifests

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.whhuang.simplest_price_compare" android:versionCode="2" android:versionName="1.01" > <uses-sdk android:minSdkVersion="11" android:targetSdkVersion="19" /> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name="com.whhuang.simplest_price_comparison.MainActivity" android:label="@string/app_name" android:screenOrientation="portrait"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>

Download & Installation:

This App can be found at the link below.

https://play.google.com/store/apps/details?id=com.whhuang.simplest_price_compare&hl=en

This is a work in progress as I am very new to Android App. development. I welcome any comments and suggestions on how to improve my skill and this App.

Further Works:

- Add support for multi-language (English, Chinese);

- Support for different screen resolutions;
- Take photo of the product and represent each product with its photo;
- Save result to local storage space;
- Save result to cloud storage;
- Beautify the UI.