Develop Reference

Toolbar image error

It's apparently a question that has been asked multiple times, but only has solutions on a case-by-case basis.I am making an aap with toolbar and when i go to second activity i want the toolbar to display icon as well as settings menu but unfortunately toolbar is appearing but icons are not showing also android monitor shows null pointer exception on these lines of code
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
Error pic
This is my activity_main
<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context="com.example.zaina.toolbar.MainActivity">
<include android:id="#+id/aap_bar" layout="#layout/aap_bar"></include>
<TextView
android:layout_below="#id/aap_bar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!" />
</RelativeLayout>
This is my MainActivity.java
package com.example.zaina.toolbar;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ImageView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
Toolbar toolbar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.aap_bar);
setSupportActionBar(toolbar);
}
#Override
public boolean onCreateOptionsMenu(Menu item) {
getMenuInflater().inflate(R.menu.menu_main, item);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem menuItem){
int id=menuItem.getItemId();
if(R.id.action_favorite==id){
startActivity(new Intent(this,aap.class));
return true;
}
if(R.id.action_settings==id){
Toast.makeText(MainActivity.this, "Hey you hit", Toast.LENGTH_SHORT).show();
return true;
}
return onOptionsItemSelected(menuItem);
}
}
This is my aapbar_xml.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:aap="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:background="#color/colorPrimary"
aap:Theme="#style/MyCustom"
app:popupTheme="#style/ThemeOverlay.AppCompat.Dark">
</android.support.v7.widget.Toolbar>
This is my activity_aap.xml
<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context="com.example.zaina.toolbar.aap">
<include android:id="#+id/app_bar" layout="#layout/aap_bar"></include>
</RelativeLayout>
This is aap.java
package com.example.zaina.toolbar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
public class aap extends AppCompatActivity{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_aap);
Toolbar toolbar= (Toolbar) findViewById(R.id.aap_bar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
}
#Override
public boolean onCreateOptionsMenu(Menu item) {
getMenuInflater().inflate(R.menu.menu_sub, item);
return true;
}
}
This is my menu_sub.xml
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:aap="http://schemas.android.com/apk/res-auto">
<item android:id="#+id/za"
android:icon="#drawable/ic_chevron_left_black_24dp"
android:title="left"
aap:showAsAction="ifRoom"/>
<item android:id="#+id/zee"
android:title="sett"
aap:showAsAction="never"/>
</menu>

There may be few reasons of NullPointException, try to:
You are probably using a Theme that doesn't support ActionBar.
Trying using this theme:
android:theme="#android:style/Theme.Holo.Light".
try to catch:
if (getSupportActionBar() != null)
{
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
}
Or, try to change the id of app_bar in aap.java

findViewById method returning null.
Add id attribute to your toolbar
android:id="#+id/aap_bar
You are also using wrong namespace aap
Use app
xmlns:app="http://schemas.android.com/apk/res-auto"

FloatingActionButton in Activity with multiple Fragments?

I have an issue that I can't seem to solve.
I have an activity with a list fragment (landscape and portrait) and an addItem fragment.
There is a FloatingActionButton on the Activity, but I can't seem to figure out how to set up its onClickListener.
The getViewById always returns null so the setOnClickListener has no object to call from. Why is this and how do I fix it?
Am I doing multiple fragments wrong and this is my problem?
Note: I left out the landscape fragment/layout for brevity's sake. It's the same as the portrait with a different id.
MainActivity.java
package tlw.app;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
ArrayList<String> activeFragments = new ArrayList<String>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
setContentView(R.layout.fragment_list);
FragmentManager fManager = getFragmentManager();
FragmentTransaction fTrans = fManager.beginTransaction();
Configuration configInfo = getResources().getConfiguration();
activeFragments.clear();
if(configInfo.orientation == Configuration.ORIENTATION_LANDSCAPE){
ListFragmentLand fragmentListLand = new ListFragmentLand();
fTrans.replace(R.id.main_container, fragmentListLand);
activeFragments.add("list_land");
} else {
ListFragment fragmentListPort = new ListFragment();
fTrans.replace(R.id.main_container, fragmentListPort);
activeFragments.add("list_port");
}
fTrans.commit();
if (activeFragments.contains("list_port") || activeFragments.contains("list_land")){
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FragmentManager fManager = getFragmentManager();
FragmentTransaction fTrans = fManager.beginTransaction();
activeFragments.clear();
ItemAddFragment fragmentAdd = new ItemAddFragment();
fTrans.replace(R.id.main_container, fragmentAdd);
activeFragments.add("add");
fTrans.commit();
}
});
}
}
}
activity_main.xml
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.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" />
</android.support.design.widget.AppBarLayout>
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
app:srcCompat="#android:drawable/ic_dialog_email" />
<FrameLayout
android:id="#+id/main_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</android.support.design.widget.CoordinatorLayout>
ListFragment.xml
package tlw.app;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class ListFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_list, container, false);
}
}
fragment_list.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:id="#+id/fragment_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context="tlw.app.MainActivity"
tools:showIn="#layout/activity_main"
android:orientation="vertical">
<TextView
android:id="#+id/text_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="List Portrait"/>
</LinearLayout>
ItemAddFragment.java
package tlw.app;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class ItemAddFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_add, container, false);
}
}
fragment_add.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_add"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="#+id/textView_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Name:"
/>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/editText_name"
/>
</LinearLayout>
</LinearLayout>

Please change this portion of the code in the MainActivity
FROM
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
setContentView(R.layout.fragment_list);
TO
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
Mistakes::
--Passing wrong xml instance::
--Trying to fetch the toolbar before the xml was actually set..
Please tell if more assistance needed

setContentView(R.layout.fragment_list);
This sets the layout used for your activity which does not have a FAB. Change this line to
setContentView(R.layout.activity_main);
In general, whenever findViewById() returns null, you need to be sure that the correct XML is loaded and that it contains the id you are trying to find.

Android Fragment not inflating after transaction

I've been trying to inflate a simple contentFragment after clicking on the tab from my navigation drawer. Here is my CentralView class that contains the attempt to inflate the Fragment
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.support.design.widget.NavigationView;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SubMenu;
import android.view.View;
import android.widget.Toast;
#SuppressWarnings("deprecation")
public class CentralView extends AppCompatActivity {
private Toolbar toolbar;
private NavigationView navigationView;
private DrawerLayout drawerLayout;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_central_view);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
navigationView = (NavigationView) findViewById(R.id.navigation_view);
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
//Checking if the item is in checked state or not, if not make it in checked state
if(menuItem.isChecked()) menuItem.setChecked(false);
else menuItem.setChecked(true);
//Closing drawer on item click
drawerLayout.closeDrawers();
//Check to see which item was being clicked and perform appropriate action
switch (menuItem.getItemId()){
//Replacing the main content with ContentFragment Which is our Inbox View;
case R.id.home:
Toast.makeText(getApplicationContext(),"Inbox Selected",Toast.LENGTH_SHORT).show();
ContentFragment fragment = new ContentFragment();
android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.frame,fragment);
fragmentTransaction.commit();
return true;
And here is my ContentFragment class
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* Created by Admin on 04-06-2015.
*/
public class ContentFragment extends Fragment {
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_content_fragment,container,false);
return v;
}
}
I've searched StackOverflow and while people have had similar issues, none of the fixes worked for me. Apologies if it's out there. Here is the XML for my content Fragment as well
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="INBOX"
android:padding="8dp"
android:textColor="#fff"
android:background="#color/colorPrimary"
android:textSize="28sp"
android:id="#+id/textView"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
edit: adding activity_central_view.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/drawer"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".CentralView">
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="vertical"
>
<include
android:id="#+id/toolbar"
layout="#layout/tool_bar"/>
<FrameLayout
android:id="#+id/frame"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>
</LinearLayout>
<android.support.design.widget.NavigationView
android:id="#+id/navigation_view"
android:layout_height="match_parent"
android:layout_width="wrap_content"
android:layout_gravity="start"
app:headerLayout="#layout/header"
app:menu="#menu/drawer"/>
</android.support.v4.widget.DrawerLayout>

I suspect your tool_bar layout might be having a height of match_parent.
Could you please share tool_bar file?

WebView in XML not working with Navigation Drawer Fragment

I am new to android and cannot find a solution online. I have a navigation drawer that leads to the fragment 'RecentNews', which is related to it's XML 'fragment_recent_news'. I have a WebView (webview) setup in the XML, and have set up the fragment so that it should load a page, but it does not. What am I doing incorrectly? I am unsure if the way to properly do this has changed in the past year because nothing online has worked. Thanks
fragment_recent_news(xml):
<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" tools:context="com.hardingsoftware.hrcfitness.RecentNews">
<WebView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/webview"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
</RelativeLayout>
RecentNews:
package com.hardingsoftware.hrcfitness;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
public class RecentNews extends Fragment {
WebView webView;
public RecentNews() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_recent_news, container, false);
WebView myWebView = (WebView) rootView.findViewById(R.id.webview);
myWebView.loadUrl("www.hrcfitness.com/recent-news/");
return rootView;
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
}
EDIT: I have the page loading now, however I now have another issue, where the webview seems to ignore the relative layout and part of it is lying under the main bar.

Android SDK error: Trying instantiate a class that is not a fragment

I am hardly trying to create a simple application with a top menu and a changeable view below (by pressing the buttons in the menu fragment we change the view of the fragment below).
So, I have 2 fragments inside the main view but when trying to run the application in the emulator I get an error like:
Cause by android.app (bla bla bla, piece of crap Eclipse doesn't even allow copying the errors):
Trying to instantiate a class com.example.android.topmenu that is not a fragment
So, these are my XML layouts:
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<fragment
android:id="#+id/menuFragment"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:name="com.example.android.topmenu" >
</fragment>
<fragment
android:id="#+id/contentFragment"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:name="com.example.android.bottomcontent" >
</fragment>
</LinearLayout>
topmenu.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<Button
android:id="#+id/Button1"
android:layout_width="wrap_content"
android:layout_height="match_parent" />
</LinearLayout>
bottom_content.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="10dp"
android:orientation="vertical">
<TextView
android:id="#+id/textView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#+string/content_text" />
</LinearLayout>
and these are the classes for the main activity and the fragments
main_activity
package com.example.android;
import com.example.android.R;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
public class OLife extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
// The activity is being created
super.onCreate(savedInstanceState);
// Set view
setContentView(R.layout.main);
}
#Override
protected void onDestroy() {
super.onDestroy();
// The activity is about to be destroyed.
super.onDestroy();
// Stop method tracing that the activity started during onCreate()
android.os.Debug.stopMethodTracing();
}
}
topmenu
package com.example.android;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class OLifeMenu extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.topmenu, container, false);
return view;
}
}
bottomcontent
package com.example.android;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class OLifeMain extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.bottom_content, container, false);
return view;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
}
}

You should be using FragmentActivity instead of Activity that is because you are using support Fragments and multiple Fragments in your activity main
Edit
You can now use the Appcompat support library and extends AppCompatActivity to support toolbar and fragment for lower api.

In my case it turned out, I was doing stuff in onCreate in the wrong order:
setContentView(R.layout.activity_qr_code_scan);
super.onCreate(savedInstanceState);
instead of
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_qr_code_scan);

As you are using fragments in your layout and I suggest you to extend your class from fragment or fragment activity.