Exercise: Hello World with EditText input

In this exercise, I will implement a simply Hello World Andrid application; there is a EditText, after user enter name and click OK button, the Title of the application will be changed accordingly.

First of all, generate a Android Project in Eclipse, as described in the previous article, Install Android SDK on Eclipse 3.5 Galileo.

Modify the main.xml to change the UI screen.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Who you are?"
/>
<EditText
android:id = "@+id/message_text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:id = "@+id/ok"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="OK" />
<Button
android:id = "@+id/cancel"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="Cancel" />
</LinearLayout>

main.xml

And then, change the HelloAndroid.java as follow:

package com.example.helloandroid;

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

public class HelloAndroid extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


       Button okButton = (Button) findViewById(R.id.ok);
       okButton.setOnClickListener(okOnClickListener);
       Button cancelButton = (Button) findViewById(R.id.cancel);
       cancelButton.setOnClickListener(cancelOnClickListener);
}
   private Button.OnClickListener okOnClickListener =
             new Button.OnClickListener(){
       @Override
       public void onClick(View v) {
           EditText edit_text = (EditText)
                findViewById(R.id.message_text);
           CharSequence edit_text_value =
                edit_text.getText();
           setTitle("Hello:"+edit_text_value);
       }
   };

   private Button.OnClickListener cancelOnClickListener =
           new Button.OnClickListener(){
       @Override
       public void onClick(View v) {
           finish();
       }
   };
}

HelloAndroid.java