Question

I am working on creating a Broadcast Receiver. I am extremely new to Android development and Java. I added my code at the bottom of this, but whenever I press the button the app crashes. I'm assuming something is wrong with connecting the broadcastIntent() function. If you could really focus on the first part that would be great!! I appreciate any help :)

Here are the directions from my professor:

1. Create an empty project
2. Create a method in MainActivity.java which creates a Broadcast.

public void broadcastIntent(View view){
       Intent intent = new Intent();
       intent.setAction("my.CUSTOM_INTENT"); sendBroadcast(intent);
   }

3. Add a button to activity_main.xml and link it to this method.
4. Is it working? How can you test it? STOP
5. Create a Broadcast Receiver (accept defaults)
6. Add the following code to your receiver in onReceive() : (remember to comment out the auto generated exception!) what’s an exception?

Toast.makeText(context, "Intent Detected.", Toast.LENGTH_LONG).show();

7. Edit your manifest by adding the following as a child node of <receiver>

<intent-filter>
    <action android:name="my.CUSTOM_INTENT"></action>
</intent-filter>

8. RUN it

MORE DIFFICULT:

1. Create a second receiver called ConnectionReciever and add the following code in onReceive():
2. ConnectivityManager cm =             (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);     NetworkInfo activeNetwork = cm.getActiveNetworkInfo();     boolean isConnected = activeNetwork != null &&             activeNetwork.isConnectedOrConnecting();     if (isConnected) {         try {             Toast.makeText(context, "Network is connected", Toast.LENGTH_LONG).show();         } catch (Exception e) {             e.printStackTrace();         }     } else {         Toast.makeText(context, "Network state has changed or reconnected", Toast.LENGTH_LONG).show();     } }
3. In your manifest include the following as your intent-filter as a node of the new receiver:

<intent-filter>

    <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />

</intent-filter>

4. Since you are being nosey – you need to ask for user- permission. Include the following as nodes of <manifest> :

<uses-permission android:name="android.permission.INTERNET" />

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

5. Test it!

MY CODE:

<MainActivity>

package com.example.ica4_broadcast;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {
    private Button mybutton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button mybutton = (Button) findViewById(R.id.mybutton);
    }

    private void broadcastIntent(View view) {
        Intent intent = new Intent();
        intent.setAction("my.CUSTOM_INTENT");
        sendBroadcast(intent);
        }

}

<activity_xml>

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/mybutton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="235dp"
        android:layout_marginEnd="146dp"
        android:layout_marginRight="146dp"
        android:onClick="broadcastIntent"
        android:text="Button"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

<manifest>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.ica4_broadcast">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.ICA4Broadcast">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <receiver android:name=".MyReceiver" android:exported="true">
            <intent-filter>
                <action android:name="my.CUSTOM_INTENT"/>
            </intent-filter>
        </receiver>
    </application>
</manifest>

<MyReceiver>

package com.example.ica4_broadcast;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
            Toast.makeText(context, "Intent Detected", Toast.LENGTH_LONG).show();

    }
}

Answer 1

Check this once hope it'll work fine

ThankYou

<MyReceiver>
public class MyReceiver extends BroadcastReceiver {
public MyReceiver() {
}

@@Override
public void onReceive(Context context, Intent intent) {
  
Toast.makeText(context, "Action: " + intent.getAction(), Toast.LENGTH_SHORT).show();
}
}
<AndroidManifest.xml>
<receiver android:name=".ConnectionReceiver" >
<intent-filter>
<action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
</intent-filter>
</receiver>

<activity_main.xml>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
xmlns:tools="https://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="com.journaldev.broadcastreceiver.MainActivity">

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/button"
android:text="Send Broadcast"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>

<MainActivity.java>

package com.journaldev.broadcastreceiver;

import android.content.Intent;
import android.content.IntentFilter;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import butterknife.ButterKnife;
import butterknife.InjectView;
import butterknife.OnClick;

public class MainActivity extends AppCompatActivity {
ConnectionReceiver receiver;
IntentFilter intentFilter;

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

ButterKnife.inject(this);

receiver = new ConnectionReceiver();
intentFilter = new IntentFilter("com.journaldev.broadcastreceiver.SOME_ACTION");

}

@@Override
protected void onResume() {
super.onResume();
registerReceiver(receiver, intentFilter);

}

@Override
protected void onDestroy() {
super.onDestroy();

unregisterReceiver(receiver);
}

@@OnClick(R.id.button)
void someMethod() {

Intent intent = new Intent("com.journaldev.broadcastreceiver.SOME_ACTION");
sendBroadcast(intent);
}
}

<AndroidManifest.xml>

<?xml version="1.0" encoding="utf-8"?>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="https://schemas.android.com/apk/res/android"
package="com.journaldev.broadcastreceiver">

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

<receiver android:name=".ConnectionReceiver">
<intent-filter>
<action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
</intent-filter>
</receiver>

</application>
</manifest>

<ConnectionReceiver.java >

public class ConnectionReceiver extends BroadcastReceiver {
@@Override
public void onReceive(Context context, Intent intent) {

Log.d("API123",""+intent.getAction());

if(intent.getAction().equals("com.journaldev.broadcastreceiver.SOME_ACTION"))
Toast.makeText(context, "SOME_ACTION is received", Toast.LENGTH_LONG).show();

else {
ConnectivityManager cm =
(ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean isConnected = activeNetwork != null &&
activeNetwork.isConnectedOrConnecting();
if (isConnected) {
try {
Toast.makeText(context, "Network is connected", Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
}
} else {
Toast.makeText(context, "Network is changed or reconnected", Toast.LENGTH_LONG).show();
}
}
}

}