CoderzHeaven

Hello everyone…

In this post I will show you how to listen to hardware button in an android smartphone.

This post especially shows how to listen to the home button in android. But my advice is never override the home button in your app.
Home button is to move the currently running process to background. But you can override the Backbutton and other buttons, android allows that on the keyDown Method. But if you try to match the “Home” button in the keyDown method it will not work. For that we have to follow another way which is shown in this post.

This simple java code handles the button pressed.

package test.test;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.WindowManager;

public class Test2Activity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
    
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_HOME)) {
        	System.out.println("KEYCODE_HOME");
        	showDialog("'HOME'");
            return true;
        }
        if ((keyCode == KeyEvent.KEYCODE_BACK)) {
        	System.out.println("KEYCODE_BACK");
        	showDialog("'BACK'");
            return true;
        }
        if ((keyCode == KeyEvent.KEYCODE_MENU)) {
        	System.out.println("KEYCODE_MENU");
        	showDialog("'MENU'");
            return true;
        }
        return false;
    }
    
    void showDialog(String the_key){
    	AlertDialog.Builder builder = new AlertDialog.Builder(this);
    	builder.setMessage("You have pressed the " + the_key + " button. Would you like to exit the app?")
    		  .setCancelable(true)
    	       .setPositiveButton("OK", new DialogInterface.OnClickListener() {
    	           public void onClick(DialogInterface dialog, int id) {
    	        	   dialog.cancel();
    	        	   finish();
    	           }
    	       })
    	       .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
    	           public void onClick(DialogInterface dialog, int id) {
    	                dialog.cancel();
    	           }
    	       });
    	AlertDialog alert = builder.create();
    	alert.setTitle("CoderzHeaven.");
    	alert.show();
    }
    
    @Override
    public void onAttachedToWindow() {
        super.onAttachedToWindow();
        this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);           
    }
    
    public void onUserLeaveHint() { // this only executes when Home is selected.
    	// do stuff
    	super.onUserLeaveHint();
    	System.out.println("HOMEEEEEEEEE");
    }
}

When “onUserLeaveHint()” function is defined you can actually listen to the home button press and do some saving of data or something.

 public void onUserLeaveHint() { // this only executes when Home is selected.
    	// do stuff
    	super.onUserLeaveHint();
    	System.out.println("HOMEEEEEEEEE");
    }

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We can create a dialog with custom alert dialog with our xml in android.
But for making simple alerts we can make custom alerts through code itself.

Here is a simple function for this. Here I am having a Listview and an edittext with two buttons in the alertBox.

  public void addDialog(){

          String test[] = {"hello1","hello2"};

    	  AlertDialog.Builder builder = new AlertDialog.Builder(this);
          builder.setCancelable(true);
          builder.setTitle("My Title");
          builder.setInverseBackgroundForced(true);
          builder.setIcon(R.drawable.android_2);
          builder.setItems(test, new OnClickListener() {
  			@Override
  			public void onClick(DialogInterface dialog, int which) {
  				System.out.println("onClick " + which);
  			}
  		  });
          builder.setAdapter(myadp, new OnClickListener() {
			@Override
			public void onClick(DialogInterface dialog, int which) {
				System.out.println("DialogInterface : " + which);
			}
		  });

          EditText ed = new EditText(this);
          builder.setView(ed);
          builder.setPositiveButton("Yes",
                  new DialogInterface.OnClickListener() {
                      @Override
                      public void onClick(DialogInterface dialog,
                              int which) {
                          dialog.dismiss();
                      }
                  });
          builder.setNegativeButton("No",
                  new DialogInterface.OnClickListener() {
                      @Override
                      public void onClick(DialogInterface dialog,
                              int which) {
                          dialog.dismiss();
                      }
                  });
          AlertDialog alert = builder.create();
          alert.show();
    }

Please leave your valuable comments on this post.

Custom Alert

Hello everyone,
Here is a simple example showing how to change the theme of default AlertDialog in android.

To start first create a fresh project named AlertTest.
In the AlertTestDemo.java file copy this code

package com.coderzheaven.pack;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.Bundle;

public class AlertTestDemo extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        AlertDialog dialog = new CustomDialog(this);
        dialog.setButton("OK", new OnClickListener()
        {
            public void onClick(DialogInterface arg0, int arg1)
            {
            }
        });
        dialog.setTitle("Coderzheaven");
        dialog.setMessage("Heaven of all working codes!! n Keep Visiting..n" +
        		"Thankyou.");
        dialog.show();
    }
}

Now create a file named “styles.xml” inside the res/values folder and copy this code into it.

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <style name="CenterTextView" parent="@android:style/Widget.TextView">
        <item name="android:gravity">center|center_vertical</item>
    </style>

    <style name="CenterJustifyDialogTitle" parent="@android:style/DialogWindowTitle" >
         <item name="android:gravity">center|center_vertical</item>
         <item name="android:textColor">#000000</item>
    </style>

	<style name="CenterJustifyTheme1" parent="@android:style/Theme.Translucent">
        <item name="android:textViewStyle">@style/CenterTextView</item>
        <item name="android:windowTitleStyle">@style/CenterJustifyDialogTitle</item>
    </style>

    <style name="CenterJustifyTheme2" parent="@android:style/Theme.Black">
        <item name="android:textViewStyle">@style/CenterTextView</item>
        <item name="android:windowTitleStyle">@style/CenterJustifyDialogTitle</item>
    </style>

    <style name="CenterJustifyTheme3" parent="@android:style/Theme.Light">
        <item name="android:textViewStyle">@style/CenterTextView</item>
        <item name="android:windowTitleStyle">@style/CenterJustifyDialogTitle</item>
    </style>

</resources>

Now create another java file named “CustomDialog.java” and copy this code into it.
We will apply the theme through this java file.
The theme is located and named in the above xml file.

package com.coderzheaven.pack;
import android.app.AlertDialog;
import android.content.Context;
import com.coderzheaven.pack.R;


public class CustomDialog extends AlertDialog {
		public CustomDialog(Context ctx)
		{
			super(ctx, R.style.CenterJustifyTheme1);
		}
}