Android Tutorial | Android SDK Development & Programming

This example shows how you can convert temperature from Celsius to Fahrenheit and vise versa.

Algorithm:

1.) Create a new project by File-> New -> Android Project name it ConvertTemperatureExample.

2.) Write following into main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/myshape"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/editText1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
	 >
    </EditText>

    <RadioGroup
        android:id="@+id/radioGroup1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <RadioButton
            android:id="@+id/radio0"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:checked="true"
            android:text="@string/celsius" >
        </RadioButton>

        <RadioButton
            android:id="@+id/radio1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/fahrenheit" >
        </RadioButton>
    </RadioGroup>

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/calc" 
        android:onClick="myClickHandler">
    </Button>

</LinearLayout>

3.) Create and write following into res/drawable/myshape.xml:

<?xml version="1.0" encoding="UTF-8"?>
<shape
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:shape="rectangle">
	<stroke
		android:width="2dp"
		android:color="#FFFFFFFF" />
	<gradient
		android:endColor="#DDBBBBBB"
		android:startColor="#DD777777"
		android:angle="90" />
	<corners
		android:bottomRightRadius="7dp"
		android:bottomLeftRadius="7dp"
		android:topLeftRadius="7dp"
		android:topRightRadius="7dp" />
</shape>

4.) Create and write following into res/values/strings.xml:

<resources>

    <string name="hello_world">Hello world!</string>
    <string name="menu_settings">Settings</string>
    <string name="title_activity_convert_temperture_example">ConvertTempertureExample</string>
    <string name="app_name">Temparature Converter</string>
    <color name="myColor">#3399CC</color>
    <string name="myClickHandler">myClickHandler</string>
    <string name="celsius">to Celsius</string>
    <string name="fahrenheit">to Fahrenheit</string>
    <string name="calc">Calculate</string>

</resources>

5.) Run for output.

Steps:

1.) Create a project named ConvertTemperatureExample and set the information as stated in the image.

Build Target: Android 4.0
Application Name: ConvertTemperatureExample
Package Name: com. example. ConvertTemperatureExample
Activity Name: ConvertTemperatureExample
Min SDK Version: 8

2.) Open ConvertTemperatureExample.java file and write following code there:

package com.example.converttemperatureexample;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.Toast;

public class ConvertTempertureExample extends Activity {
	private EditText text;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		text = (EditText) findViewById(R.id.editText1);

	}

	// This method is called at button click because we assigned the name to the
	// "On Click property" of the button
	public void myClickHandler(View view) {
		switch (view.getId()) {
		case R.id.button1:
			RadioButton celsiusButton = (RadioButton) findViewById(R.id.radio0);
			RadioButton fahrenheitButton = (RadioButton) findViewById(R.id.radio1);
			if (text.getText().length() == 0) {
				Toast.makeText(this, "Please enter a valid number",
						Toast.LENGTH_LONG).show();
				return;
			}

			float inputValue = Float.parseFloat(text.getText().toString());
			if (celsiusButton.isChecked()) {
				text.setText(String
						.valueOf(convertFahrenheitToCelsius(inputValue)));
				celsiusButton.setChecked(false);
				fahrenheitButton.setChecked(true);
			} else {
				text.setText(String
						.valueOf(convertCelsiusToFahrenheit(inputValue)));
				fahrenheitButton.setChecked(false);
				celsiusButton.setChecked(true);
			}
			break;
		}
	}

	// Converts to celsius
	private float convertFahrenheitToCelsius(float fahrenheit) {
		return ((fahrenheit - 32) * 5 / 9);
	}

	// Converts to fahrenheit
	private float convertCelsiusToFahrenheit(float celsius) {
		return ((celsius * 9) / 5) + 32;
	}
}

3.) Compile and build the project.

Output