Android File Handling

Lets learn File handling in Android.

First, create a layout to enter and save the data and to display the saved data.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context=".MainActivity" >

    <EditText 

        android:id="@+id/et"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:hint="Enter Here"

        />

    

    <TextView

        android:id="@+id/tv"

        android:layout_below="@+id/et"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        />

    <Button

        android:id="@+id/read"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignBaseline="@+id/save"

        android:layout_alignBottom="@+id/save"

        android:layout_toRightOf="@+id/save"

        android:text="READ" />

    <Button

        android:id="@+id/save"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignLeft="@+id/tv"

        android:layout_centerVertical="true"

        android:text="SAVE" />

</RelativeLayout>

And then make changes in the MainActivity.java.

package com.codingredefined.androidfilehandling;

import java.io.FileInputStream;
import java.io.FileOutputStream;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity
{
Button b1,b2;
EditText et;
TextView tv;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
b1=(Button)findViewById(R.id.save);
b2=(Button)findViewById(R.id.read);
et=(EditText)findViewById(R.id.et);
tv=(TextView)findViewById(R.id.tv);
b1.setOnClickListener(new View.OnClickListener()
{

@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
String str=et.getText().toString();
FileOutputStream fos;
try
{
fos=openFileOutput("abc",Context.MODE_PRIVATE);
fos.write(str.getBytes());
fos.close();
Toast.makeText(MainActivity.this,"Data Saved",Toast.LENGTH_SHORT).show();
}
catch(Exception e)
{
Toast.makeText(MainActivity.this,"Data NOT Saved",Toast.LENGTH_SHORT).show();
}
}
});
b2.setOnClickListener(new View.OnClickListener()
{

@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
FileInputStream fis;
try
{
fis=openFileInput("abc");
int i=0;
String str="";
while((i=fis.read())!=-1)
{
str=str+((char)+i);
}
tv.setText(str);
fis.close();
}
catch(Exception e)
{
Toast.makeText(MainActivity.this,"Data NOT Read",Toast.LENGTH_SHORT).show();
}
}
});
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}

The following output is obtained.

Android Notification

Learn to create Notification.

Open the project folder and create a new folder "raw" in the res folder. Put a .mp3 file which you want to use as notification sound.

Do the following coding in the MainActivity.java file.

package com.codingredefined.notification;

import android.media.AudioManager;

import android.media.MediaPlayer;

import android.os.Bundle;

import android.app.Activity;

import android.app.Notification;

import android.app.NotificationManager;

import android.app.PendingIntent;

import android.content.Context;

import android.content.Intent;

import android.view.Menu;

public class MainActivity extends Activity 

{

private static final int HELLO_ID=1;

MediaPlayer mMediaPlayer;

@Override

protected void onCreate(Bundle savedInstanceState) 

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

String ns=Context.NOTIFICATION_SERVICE;

NotificationManager mNotificationManager=(NotificationManager)getSystemService(ns);

int icon=R.drawable.ic_launcher;

CharSequence tickerText="Hello!";

long when=System.currentTimeMillis();

Notification notification=new Notification(icon, tickerText, when);

//Vibrate on Notification

notification.defaults=Notification.DEFAULT_VIBRATE;

long[] vibrate={0,100,200,300};

notification.vibrate=vibrate;

//Glow LED

notification.defaults=Notification.DEFAULT_LIGHTS;

notification.ledARGB=0xff00ff00;

notification.ledOnMS=300;

notification.ledOffMS=1000;

notification.flags=Notification.FLAG_SHOW_LIGHTS;

//Activate notification

Context context=getApplicationContext();

CharSequence contextTitle="My Notification";

CharSequence contextText="Hello World!!!";

Intent notificationIntent=new Intent(this,MainActivity1.class);

PendingIntent contentIntent=PendingIntent.getActivity(this, 0, notificationIntent, 0);

notification.setLatestEventInfo(context, contextTitle, contextText, contentIntent);

mNotificationManager.notify(HELLO_ID, notification);

//Sound

mNotificationManager.notify(HELLO_ID, notification);

mMediaPlayer=new MediaPlayer();

mMediaPlayer=MediaPlayer.create(this,R.raw.abc);

mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);

mMediaPlayer.setLooping(true);

mMediaPlayer.start();

Thread t=new Thread()

{

@Override

public void run()

{

try

{

Thread.sleep(5000);

}

catch(Exception e){}

mMediaPlayer.stop();

}

};

t.start();

}

@Override

public boolean onCreateOptionsMenu(Menu menu) 

{

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.main, menu);

return true;

}

}

The following output will be obtained.

Web View

WebView is a view which can display web pages in your activity.

Create a webview in layout file.

<WebView
android:id="@+id/webview"
android:layout_width="match_parent"
android:layout_height="200dp" />

The button created in the below image is of no use.

Make the changes in the Activity file.

package com.codingredefined.webview;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.Window;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends Activity
{
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getWindow().setFeatureInt(Window.FEATURE_PROGRESS, Window.PROGRESS_VISIBILITY_ON);
WebView mywebView;
mywebView=(WebView)findViewById(R.id.webview);
mywebView.getSettings().setJavaScriptEnabled(true);
mywebView.loadUrl("http://www.google.com");
mywebView.setWebViewClient(new WebViewClient());
mywebView.setInitialScale(1);
mywebView.getSettings().setUseWideViewPort(true);
final Activity MyActivity=this;
mywebView.setWebChromeClient(new WebChromeClient()
{
public void onProgressChanged(WebView view,int progress)
{
MyActivity.setTitle("Loading...");
MyActivity.setProgress(progress*100);
if(progress==100)
{
MyActivity.setTitle("WebView");
}
}
});
}

@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}

This will be the output.

Progress Bar

Now these are the steps to create a Progress Bar in your app...

Create a Button and a Progress Bar in main layout file.

<TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Progress Bar" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView1"
        android:layout_below="@+id/textView1"
        android:layout_marginTop="60dp"
        android:onClick="startProgress"
        android:text="Start Progress Bar" />

    <ProgressBar
        android:id="@+id/progressBar1"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/button1"
        android:layout_below="@+id/textView1"
        android:layout_marginTop="30dp"
        android:indeterminate="false"
        android:max="10"
        android:padding="4dp" />

Code your activity file.

package com.codingredefined.progressbar;

import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.ProgressBar;

public class MainActivity extends Activity
{
private Handler handler;
private ProgressBar progress;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
progress=(ProgressBar)findViewById(R.id.progressBar1);
handler=new Handler();
}

public void startProgress(View view)
{
Runnable runnable=new Runnable()
{
@Override
public void run()
{
for(int i=0;i<=10;i++)
{
final int value=i;
try
{
Thread.sleep(1500);
}
catch(Exception e)
{}
handler.post(new Runnable()
{
@Override
public void run()
{
progress.setProgress(value);
}
});
}
}
};
new Thread(runnable).start();
}

}

The following output will be obtained.

Custom Dialog

So here we are with a simple method to create a own designed dialog box.

Create a button to activate the dialog box.

<TextView

        android:id="@+id/textView1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentLeft="true"

        android:layout_alignParentTop="true"

        android:text="Click Button"

        android:textAppearance="?android:attr/textAppearanceLarge" />

    <Button

        android:id="@+id/buttonShowCustomDialog"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@+id/textView1"

        android:layout_centerHorizontal="true"

        android:layout_marginTop="30dp"

        android:text="Button" />

Now create a new layout file named "custom_dialog.xml" to design your dialog box.

<ImageView
    android:id="@+id/image"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginRight="5dp"
    />

<TextView
    android:id="@+id/text"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:textColor="#DC143C"
    android:layout_toRightOf="@+id/image"
    />
   
<Button
    android:id="@+id/dialogButtonOK"
    android:layout_width="100px"
    android:layout_height="wrap_content"
    android:text="OK"
    android:layout_marginTop="5dp"
    android:layout_marginRight="5dp"
    android:layout_below="@+id/image"
    />

Now make changes in the main activity file.

package com.codingredefined.customdialog;

import android.os.Bundle;
import android.app.Activity;
import android.app.Dialog;
import android.content.Context;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity
{
Button button;
Context context;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context=this;
button=(Button)findViewById(R.id.buttonShowCustomDialog);
button.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
final Dialog dialog=new Dialog(context);
dialog.setContentView(R.layout.custom_dialog);
dialog.setTitle("Custom Dialog");
TextView text=(TextView)dialog.findViewById(R.id.text);
text.setText("Android Custom Dialog");
ImageView image=(ImageView)dialog.findViewById(R.id.image);
image.setImageResource(R.drawable.ic_launcher);
Button dialogButton=(Button)dialog.findViewById(R.id.dialogButtonOK);
dialogButton.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
dialog.dismiss();
}
});
dialog.show();
}
});
}

}

Following output will be obtained.

Hyperlink in a Text View

Now we will learn to embed Hyperlinks in a TextView.

First make a text view in the layout file.

<TextView

        android:id="@+id/tv"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="@string/link1" />

Now open the "strings.xml" file under the "values" folder. And add the following code to it.

<string name="link1"><![CDATA[This is Link to <a href="http://www.google.com/">Google</a>]]></string>

Finally make changes in the activity file.

package com.codingredefined.linkinatextview;

import android.os.Bundle;
import android.app.Activity;
import android.text.Html;
import android.text.method.LinkMovementMethod;
import android.text.util.Linkify;
import android.view.Menu;
import android.widget.TextView;

public class MainActivity extends Activity
{

@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

TextView tv=(TextView)findViewById(R.id.tv);
tv.setText(Html.fromHtml(getString(R.string.link1)));
Linkify.addLinks(tv, Linkify.ALL);
tv.setMovementMethod(LinkMovementMethod.getInstance());
}

}

The following output will be obtained.

Clicking on Google will automatically open google.com in your default browser.

Custom Toast

So back to blogging after a long time with a lot new stuff.

This time we are making a CUSTOM toast designed completely by you.

This is what will appear as a toast when you will click the button.

First create a button in the native layout file to trigger the toast.

<Button

        android:id="@+id/buttonShow"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentTop="true"

        android:layout_centerHorizontal="true"

        android:layout_marginTop="50dp"

        android:text="Show Custom Toast" />

After that create a new layout file in the same folder named "custom_toast.xml". And create an image view and a text view in that layout file.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/toast_layout_root"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
 
    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_marginRight="10dp"
        />
 
    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:textColor="#DC143C"
        />

</RelativeLayout>

Now the final step is to make changes in the activity file.

package com.codingredefined.customtoast;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity
{
Button button;
Context context;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button=(Button)findViewById(R.id.buttonShow);
button.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
LayoutInflater inflater=getLayoutInflater();
View layout=inflater.inflate(R.layout.custom_toast,(ViewGroup)findViewById(R.id.toast_layout_root));
ImageView image=(ImageView)layout.findViewById(R.id.image);
image.setImageResource(R.raw.reebok);
TextView text=(TextView)layout.findViewById(R.id.text);
Toast toast=new Toast(getApplicationContext());
toast.setGravity(Gravity.CENTER_VERTICAL, 0, 0);
toast.setDuration(Toast.LENGTH_LONG);
toast.setView(layout);
toast.show();
}
});
}

}

The following output should be observed.