E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.spammessagedetector, PID: 2137
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.spammessagedetector/com.example.spammessagedetector.Inbox}:
java.lang.NullPointerException: Attempt to invoke virtual method 'void
androidx.swiperefreshlayout.widget.SwipeRefreshLayout.setOnRefreshListener(androidx.swiperefreshlayout.widget.SwipeRefreshLayout$OnRefreshListener)'
on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void
androidx.swiperefreshlayout.widget.SwipeRefreshLayout.setOnRefreshListener(androidx.swiperefreshlayout.widget.SwipeRefreshLayout$OnRefreshListener)'
on a null object reference
at com.example.spammessagedetector.Inbox.onCreate(Inbox.java:76)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
here is the code for Inbox.java
package com.example.spammessagedetector;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.view.ActionMode;
import androidx.appcompat.widget.Toolbar;
import androidx.recyclerview.widget.DefaultItemAnimator;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
import android.os.Bundle;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
import com.example.spammessagedetector.R;
import com.example.spammessagedetector.adapter.MessagesAdapter;
import com.example.spammessagedetector.helper.DividerItemDecoration;
import com.example.spammessagedetector.model.Message;
import com.example.spammessagedetector.network.ApiClient;
import com.example.spammessagedetector.network.ApiInterface;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
public class Inbox extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener, MessagesAdapter.MessageAdapterListener{
private List<Message> messages = new ArrayList<>();
private RecyclerView recyclerView;
private MessagesAdapter mAdapter;
private SwipeRefreshLayout swipeRefreshLayout;
private ActionModeCallback actionModeCallback;
private ActionMode actionMode;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_inbox);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
if (fab != null)
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_refresh_layout);
swipeRefreshLayout.setOnRefreshListener(this);
mAdapter = new MessagesAdapter(this, messages, this);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getApplicationContext());
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.VERTICAL));
recyclerView.setAdapter(mAdapter);
actionModeCallback = new ActionModeCallback();
// show loader and fetch messages
swipeRefreshLayout.post(
new Runnable() {
@Override
public void run() {
getInbox();
}
}
);
}
/**
* Fetches mail messages by making HTTP request
* url: https://api.androidhive.info/json/inbox.json
*/
private void getInbox() {
swipeRefreshLayout.setRefreshing(true);
ApiInterface apiService =
ApiClient.getClient().create(ApiInterface.class);
Call<List<Message>> call = apiService.getInbox();
call.enqueue(new Callback<List<Message>>() {
@Override
public void onResponse(Call<List<Message>> call, Response<List<Message>> response) {
// clear the inbox
messages.clear();
// add all the messages
// messages.addAll(response.body());
// TODO - avoid looping
// the loop was performed to add colors to each message
for (Message message : response.body()) {
// generate a random color
message.setColor(getRandomMaterialColor("400"));
messages.add(message);
}
mAdapter.notifyDataSetChanged();
swipeRefreshLayout.setRefreshing(false);
}
@Override
public void onFailure(Call<List<Message>> call, Throwable t) {
Toast.makeText(getApplicationContext(), "Unable to fetch json: " + t.getMessage(), Toast.LENGTH_LONG).show();
swipeRefreshLayout.setRefreshing(false);
}
});
}
/**
* chooses a random color from array.xml
*/
private int getRandomMaterialColor(String typeColor) {
int returnColor = Color.GRAY;
int arrayId = getResources().getIdentifier("mdcolor_" + typeColor, "array", getPackageName());
if (arrayId != 0) {
TypedArray colors = getResources().obtainTypedArray(arrayId);
int index = (int) (Math.random() * colors.length());
returnColor = colors.getColor(index, Color.GRAY);
colors.recycle();
}
return returnColor;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_search) {
Toast.makeText(getApplicationContext(), "Search...", Toast.LENGTH_SHORT).show();
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onRefresh() {
// swipe refresh is performed, fetch the messages again
getInbox();
}
@Override
public void onIconClicked(int position) {
if (actionMode == null) {
actionMode = startSupportActionMode(actionModeCallback);
}
toggleSelection(position);
}
@Override
public void onIconImportantClicked(int position) {
// Star icon is clicked,
// mark the message as important
Message message = messages.get(position);
message.setImportant(!message.isImportant());
messages.set(position, message);
mAdapter.notifyDataSetChanged();
}
@Override
public void onMessageRowClicked(int position) {
// verify whether action mode is enabled or not
// if enabled, change the row state to activated
if (mAdapter.getSelectedItemCount() > 0) {
enableActionMode(position);
} else {
// read the message which removes bold from the row
Message message = messages.get(position);
message.setRead(true);
messages.set(position, message);
mAdapter.notifyDataSetChanged();
Toast.makeText(getApplicationContext(), "Read: " + message.getMessage(), Toast.LENGTH_SHORT).show();
}
}
@Override
public void onRowLongClicked(int position) {
// long press is performed, enable action mode
enableActionMode(position);
}
private void enableActionMode(int position) {
if (actionMode == null) {
actionMode = startSupportActionMode(actionModeCallback);
}
toggleSelection(position);
}
private void toggleSelection(int position) {
mAdapter.toggleSelection(position);
int count = mAdapter.getSelectedItemCount();
if (count == 0) {
actionMode.finish();
} else {
actionMode.setTitle(String.valueOf(count));
actionMode.invalidate();
}
}
private class ActionModeCallback implements ActionMode.Callback {
@Override
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
mode.getMenuInflater().inflate(R.menu.menu_action_mode, menu);
// disable swipe refresh if action mode is enabled
swipeRefreshLayout.setEnabled(false);
return true;
}
@Override
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
return false;
}
@Override
public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
switch (item.getItemId()) {
case R.id.action_delete:
// delete all the selected messages
deleteMessages();
mode.finish();
return true;
default:
return false;
}
}
@Override
public void onDestroyActionMode(ActionMode mode) {
mAdapter.clearSelections();
swipeRefreshLayout.setEnabled(true);
actionMode = null;
recyclerView.post(new Runnable() {
@Override
public void run() {
mAdapter.resetAnimationIndex();
// mAdapter.notifyDataSetChanged();
}
});
}
}
// deleting the messages from recycler view
private void deleteMessages() {
mAdapter.resetAnimationIndex();
List<Integer> selectedItemPositions =
mAdapter.getSelectedItems();
for (int i = selectedItemPositions.size() - 1; i >= 0; i--) {
mAdapter.removeData(selectedItemPositions.get(i));
}
mAdapter.notifyDataSetChanged();
}
}
activity_inbox.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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:mContext=".Inbox">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay"/>
</com.google.android.material.appbar.AppBarLayout>
<include layout="@layout/content_main"/>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/fab"
android:onClick="floatbuttonclick"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="bottom|end"
android:layout_margin="@dimen/fab_margin"
app:backgroundTint="@color/colorPrimary"
app:srcCompat="@drawable/ic_edit_white_24dp"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.spammessagedetector">
<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/AppTheme.NoActionBar">
<!-- <activity android:name=".Inbox"></activity> -->
<activity android:name=".MainActivity" />
<activity android:name=".Profile" />
<activity android:name=".Splash" />
<activity android:name=".Inbox">
<!-- android:theme="@style/splash" -->
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
