Part 3 of 3

CPET 565 Mobile Computing Systems
CPET/ITC 499 Mobile Computing
Lab & Demo 2 (3 of 3)
Hello-Goodbye App Tutorial
Reference

Android Programming Concepts, by Trish Cornez and Richard
Cornez, pubslihed by Jones & Barlett Learning, pp. 22-67.

Android Developer API Guides,
http://developer.android.com/guide/index.html
Paul I-Hai Lin, Professor
Spring 2016
A Specialty Course
Purdue University M.S. Technology Graduate Program
Dept. of Computer, Electrical and Information Technology
Purdue University Fort Wayne Campus
Prof. Paul Lin
1
Hello-Goodbye App
 Coding the Activity for the “Hello-Goodbye” app.
 Open MainActivity file located in java.com.yourName.hellogoodbye
Prof. Paul Lin
2
1
Hello-Goodbye App
 Coding the Activity for the “Hello-Goodbye” app.
 Open MainActivity file located in java.com.yourName.hellogoodbye
Prof. Paul Lin
3
Hello-Goodbye App
 Edit the Java code as shown below (see pp. 54-55 – some errors??)
Prof. Paul Lin
4
2
Hello-Goodbye App
 Edit the Java code as shown below (see pp. 54-55 – some errors??)
Prof. Paul Lin
5
Hello-Goodbye App
 Edit the Java code as shown below (see pp. 54-55 – some errors??)
Prof. Paul Lin
6
3
Hello-Goodbye App
 The revised Java code as shown below (see pp. 54-55 – some errors??)
package com.example.lin.hellogoodbye;
import android.app.Activity;
import android.widget.Button;
import android.widget.TextView;
import android.os.Bundle;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends Activity {
// Declare text reference to the Interface Layout Component
private TextView greetingTextView;
// Indicate Hello is currently Displayed
private boolean isHello;
Prof. Paul Lin
7
Hello-Goodbye App
 The revised Java code as shown below - continue
@Override
protected void onCreate(Bundle savedInstanceState) {
//TASK 1: Inflate the main screen layout used by the app
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//TASK 2: Establish references to the TextView and Button
greetingTextView = (TextView) findViewById(R.id.textView);
//TASK 3: Initialze Greetings
initializeGreeting();
//TASK 4: Register the Listner Event for the Button
Button exclaim_btn = (Button) findViewById(R.id.button);
exclaim_btn.setOnClickListener(toggleGreeting);
}
Prof. Paul Lin
8
4
Hello-Goodbye App
 The revised Java code as shown below - continue
private final View.OnClickListener toggleGreeting = new
View.OnClickListener(){
public void onClick(View btn){
//Task: Construct the toggle greeting
if(isHello) {
isHello = false;
greetingTextView.setText(R.string.goodbye);
}
else{
isHello = true;
greetingTextView.setText(R.string.hello);
}
}
};
Prof. Paul Lin
9
Hello-Goodbye App
 The revised Java code as shown below - continue
private void initializeGreeting(){
isHello = true;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
Prof. Paul Lin
10
5
Hello-Goodbye App
 The revised Java code as shown below - continue
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Prof. Paul Lin
11
Hello-Goodbye App
 Click the green triangle
to run the app using Emulator.
Prof. Paul Lin
12
6
Hello-Goodbye App
 Click the green triangle
to run the app using Emulator.
 Click EXCLAIMATION button to say “Goodbte”
Prof. Paul Lin
13
Hello-Goodbye App
The Smartphone Screen
Prof. Paul Lin
14
7
Summary
Q/A?
Prof. Paul Lin
15
8