Detect Key action

To detect key action of Android device from user, you can override the methods onKeyDown() and onKeyUp().

Example:

package com.AndroidKey;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.widget.Toast;

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

 @Override
 public boolean onKeyDown(int keyCode, KeyEvent event) {
  // TODO Auto-generated method stub
  
  switch(keyCode){
  case KeyEvent.KEYCODE_MENU:
   Toast.makeText(AndroidKey.this, "KEYCODE_MENU", Toast.LENGTH_LONG).show();
   return true;
  case KeyEvent.KEYCODE_SEARCH:
   Toast.makeText(AndroidKey.this, "KEYCODE_SEARCH", Toast.LENGTH_LONG).show();
   return true;
  //...more case...
  default:
   return super.onKeyDown(keyCode, event);
  }
 }
}

Pass data from activity to service

In activity:

 Intent myIntent = new Intent(MainActivity.this, MyService.class);
    
 Bundle bundle = new Bundle();
 bundle.putCharSequence("extraData", data);
 myIntent.putExtras(bundle);
    
 pendingIntent = PendingIntent.getService(MainActivity.this, 0, myIntent, 0);

Basically, it's similar to that in "Pass data between activity".

In service side, there are no getIntent().getExtras() in Service class. We can handle it in onStart() call-back method, intent will be passed as parameter.

 public void onStart(Intent intent, int startId) {
  // TODO Auto-generated method stub
  super.onStart(intent, startId);
  
  Bundle bundle = intent.getExtras();
  data = (String) bundle.getCharSequence("extraData");
  smsTextToSend = (String) bundle.getCharSequence("extraSmsText");
  ...
 }

Pass data between activity

When start a new activity in our main activity using startActivity(), data can be passed using Bundle.

Inside the main activity, MainActivity.java

            Intent intent = new Intent();
           intent.setClass(MainActivity.this, NewActivity.class);
          
           Bundle bundle = new Bundle();
           bundle.putCharSequence("extraCharSequence", "hello");
           bundle.putInt("extraInt", 12345);
           //...
           intent.putExtras(bundle);
           startActivity(intent);

Get the data in onCreate() of the new activity, NewActivity.java

    public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
      
       Bundle bundle = this.getIntent().getExtras();
       CharSequence dataCharSequence = bundle.getCharSequence("extraCharSequence");
       int dataInt = bundle.getCharSequence("extraInt");
      

    };

The code this.getIntent().getExtras() return the map of all extras previously added with putExtra(), or null if none have been added.

Send email by startActivity with Intent.ACTION_SEND

Here is a example by calling startActivity() with Intent.ACTION_SEND. Android OS will start a app Chooser suitable for "plain/text" email sending.

    String emailList[] = {emailAddress1, emailAddress2, ...};
    
    Intent intent = new Intent(Intent.ACTION_SEND);  
    intent.setType("plain/text");
    intent.putExtra(Intent.EXTRA_EMAIL, emailList);   
    intent.putExtra(Intent.EXTRA_SUBJECT, "Email Subject");  
    intent.putExtra(Intent.EXTRA_TEXT, "Email Text");  
    startActivity(Intent.createChooser(intent, "Choice email App"));

Send SMS by startActivity with Intent.ACTION_SENDTO

Here is a example by calling startActivity() with Intent.ACTION_SENDTO. Android default SMS app will be started to send SMS with pre-defined text and number.

remark: change "xxxxxxxx" to the number of the phone to receive SMS.

        Uri uri = Uri.parse("smsto:xxxxxxxx");  
        Intent intent = new Intent(Intent.ACTION_SENDTO, uri);  
        intent.putExtra("sms_body", "SMS text");    
        startActivity(intent);