Onnowpurbo: New page: In this tutorial we’ll start making a useful Android unit conversion app. I’ll show you everything this time because I on purpose didn’t pre-plan anything. I’ll cover relative lay...

2015-03-18T08:21:05Z

New page: In this tutorial we’ll start making a useful Android unit conversion app. I’ll show you everything this time because I on purpose didn’t pre-plan anything. I’ll cover relative lay...

New page

In this tutorial we’ll start making a useful Android unit conversion app. I’ll show you everything this time because I on purpose didn’t pre-plan anything.

I’ll cover relative layouts, grid layouts, array resources, Array Adapters, Spinners, and more. In the next video I’ll finish the entire app. Like always all the code follows the video below. If it is still the month of July 2014, don’t forget to sign up to win a Samsung Galaxy Note 3 in my current contest.

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Code From the Video

Use Case Description

SIMPLE ACTIONS

1. The user enters a number they want converted
into an EditText

2. They change the spinner to the unit of
measure to convert from

3. The other conversion types all show their
measurement version of that unit amount

1. Create the layout in
activity_main.xml

a. Use relative layout for for
label "Convert From", Edittext and
Spinner

b. Use GridLayout for bottom that
contains 2 columns and 6 rows

c. Make gridlayout a blue color

d. Use the units teaspoons, tablespoons,
cup, ounces, pints, quarts, gallons,
pounds, milliliter, liter, milligram
kilograms

2. Setup MainActivity

a. Create Spinner, EditText, TextViews

b. In onCreate

I. add items to the spinner

i. Create an ArrayAdapter using String array resource
(Make strings.xml)

ii. Define the layout to use with the Spinner

iii. Connect the Adapter to the Spinner

II. Add a listener to the Spinner

i. Use setOnItemSelectedListener for Spinner

ii. NOTE : Maybe check if I am going to use a base class for unit
conversion

III. Get the value in the EditText

IV. Initialize the TextViews

activity_main.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:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.newthinktank.androidlayouts2.app.MainActivity">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="@string/convert_from_text"
android:id="@+id/convert_from_text_view"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginRight="20dp" />

<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/amount_text_view"
android:layout_alignParentTop="true"
android:layout_toRightOf="@+id/convert_from_text_view"
android:inputType="numberDecimal"
android:text="1.0"/>

<Spinner
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/unit_type_spinner"
android:layout_below="@+id/amount_text_view"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"/>


<GridLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="@+id/unit_type_spinner"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:columnCount="2"
android:rowCount="6"
android:orientation="horizontal"
android:background="#ffdae6ff"
android:padding="15dp">

<TextView
android:id="@+id/tsp_text_view"
android:text="@string/default_teaspoon_value"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="left|top"
android:layout_marginRight="30dp"
android:layout_marginBottom="30dp" />

<TextView
android:id="@+id/cup_text_view"
android:text=".0208 cup"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="left|top" />

<TextView
android:id="@+id/tbs_text_view"
android:text=".3333 tbs"
android:layout_gravity="left|top"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_marginRight="30dp"
android:layout_marginBottom="30dp" />

<TextView
android:id="@+id/oz_text_view"
android:text=".1666 oz"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="left|top" />

<TextView
android:id="@+id/kg_text_view"
android:text=".0057 kg"
android:layout_gravity="left|top"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_marginRight="30dp"
android:layout_marginBottom="30dp" />

<TextView
android:id="@+id/quart_text_view"
android:text=".0052 quart"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="left|top" />

<TextView
android:id="@+id/gallon_text_view"
android:text=".0013 gallon"
android:layout_gravity="left|top"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_marginRight="30dp"
android:layout_marginBottom="30dp" />

<TextView
android:id="@+id/pound_text_view"
android:text=".0125 pound"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="left|top" />

<TextView
android:id="@+id/ml_text_view"
android:text="4.9289 ml"
android:layout_gravity="left|top"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_marginRight="30dp"
android:layout_marginBottom="30dp" />

<TextView
android:id="@+id/liter_text_view"
android:text=".0049 liter"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="left|top" />

<TextView
android:id="@+id/mg_text_view"
android:text="5687.5000 mg"
android:layout_gravity="left|top"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_marginRight="30dp"
android:layout_marginBottom="15dp" />

<TextView
android:id="@+id/pint_text_view"
android:text=".0104 pint"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_gravity="left|top" />

</GridLayout>



</RelativeLayout>

MainActivity.java

package com.newthinktank.androidlayouts2.app;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity {

private Spinner unitTypeSpinner;

private EditText amountTextView;

TextView teaspoonTextView, tablespoonTextView, cupTextView, ounceTextView,
pintTextView, quartTextView, gallonTextView, poundTextView,
milliliterTextView, literTextView, milligramTextView, kilogramTextView;

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

// Fills the spinner with the unit options
addItemsToUnitTypeSpinner();

// Add listener to the Spinner
addListenerToUnitTypeSpinner();

// Get a reference to the edit text view to retrieve the amount of the unit type
amountTextView = (EditText) findViewById(R.id.amount_text_view);

initializeTextViews();

}

public void initializeTextViews(){

teaspoonTextView = (TextView) findViewById(R.id.tsp_text_view);
tablespoonTextView = (TextView) findViewById(R.id.tbs_text_view);
cupTextView = (TextView) findViewById(R.id.cup_text_view);
ounceTextView = (TextView) findViewById(R.id.oz_text_view);
pintTextView = (TextView) findViewById(R.id.pint_text_view);
quartTextView = (TextView) findViewById(R.id.quart_text_view);
gallonTextView = (TextView) findViewById(R.id.gallon_text_view);
poundTextView = (TextView) findViewById(R.id.pound_text_view);
milliliterTextView = (TextView) findViewById(R.id.ml_text_view);
literTextView = (TextView) findViewById(R.id.liter_text_view);
milligramTextView = (TextView) findViewById(R.id.mg_text_view);
kilogramTextView = (TextView) findViewById(R.id.kg_text_view);

}

public void addItemsToUnitTypeSpinner(){

// Get a reference to the spinner
unitTypeSpinner = (Spinner) findViewById(R.id.unit_type_spinner);

// Create an ArrayAdapter using the string array and a default spinner layout
ArrayAdapter<CharSequence> unitTypeSpinnerAdapter = ArrayAdapter.createFromResource(this,
R.array.conversion_types, android.R.layout.simple_spinner_item);

// Specify the layout to use when the list of choices appears
unitTypeSpinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

// Apply the adapter to the spinner
unitTypeSpinner.setAdapter(unitTypeSpinnerAdapter);

}

public void addListenerToUnitTypeSpinner() {
unitTypeSpinner = (Spinner) findViewById(R.id.unit_type_spinner);
unitTypeSpinner.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> parent, View arg1, int pos, long arg3)
{
// Get the item selected in the Spinner
String itemSelectedInSpinner = parent.getItemAtPosition(pos).toString();

// Verify if I'm converting from teaspoon so that I use the right
// conversion algorithm
checkIfConvertingFromTsp(itemSelectedInSpinner);

}
public void onNothingSelected(AdapterView<?> arg0)
{
// TODO maybe add something here later
}
});
}

conversion_types.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string-array name="conversion_types">
<item>teaspoon</item>
<item>tablespoon</item>
<item>cup</item>
<item>ounce</item>
<item>pint</item>
<item>quart</item>
<item>gallon</item>
<item>pound</item>
<item>milliliter</item>
<item>liter</item>
<item>milligram</item>
<item>kilogram</item>
</string-array>
</resources>

- See more at: http://www.newthinktank.com/2014/07/make-android-apps-7/#sthash.kPcaXnO6.dpuf

==Referensi==

* http://www.newthinktank.com/2014/07/make-android-apps-7/

Android Studio: Cara Membuat Android Apps 7 - Revision history

Onnowpurbo: New page: In this tutorial we’ll start making a useful Android unit conversion app. I’ll show you everything this time because I on purpose didn’t pre-plan anything. I’ll cover relative lay...