I create an app using binding and I get an error that I couldn't solve.
The error is
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.newtest/com.example.mylibrary.MainActivity1}: java.lang.NullPointerException: Missing required view with ID: com.example.newtest:id/myRecyclerview
Thanks!
public class MainActivity1 extends AppCompatActivity {
RecyclerView.LayoutManager layoutManager;
ArrayList<POJOimage>pojoImageArrayList;
ActivityMainBinding binding;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
binding = ActivityMainBinding.inflate(getLayoutInflater());
setContentView(binding.getRoot());
layoutManager = new LinearLayoutManager(this);
binding.myRecyclerview.setLayoutManager(layoutManager);
init();
}
XML:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
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=".MainActivity1"
android:background="#000"
android:padding="10dp">
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/myRecyclerview"/>
</androidx.constraintlayout.widget.ConstraintLayout>
I strongly suspect some Android Studio bug.
I had the same bug, and everything I've had done was adding some TextView.
As it was easy to find this difference, I've just started fiddling with this TextView in xml. At some point bug disappeared.
And here comes the best. Before starting to deal with the problem I've saved problematic change with git. So at the end I've reapplied this change and ... everything worked. No more bug !
P.S. As this bug reappears, I've found that the easiest solution for getting rid of it is to use "Clean Project" from "Build" menu.
Related
It says that "cannot resolve the symbol activity_sign_up" when I created a new empty activity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sign_up);
}
Added xml resource file code :
<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=".SignUp">
Rebuild the project and check. If it didn't work just restart the Android studio. Happens for most of the people. Let me know if it worked or will try to help you out differently.
I am doing a java to c# transition, and need help.
in Visual Studio 2019 Pro, Android 9.0 (Pie), I am doing this example:
https://learn.microsoft.com/en-us/xamarin/android/platform/binding-java-library/binding-a-jar
The goal is later to convert my java libs to c# for my big project.
I follow the instructions to the letter, and when I come to the part where I need to create an ImageView, there is the problem. Once I create the ImageView, it has an android:src field, something like this (auto generated):
android:src="#drawable/icon"
The problem here, is when I remove that field, in the VS designer, the ImageView disappears and it does not matter if I have the c# code or not, even when I set the srec to:""
Bellow is literally all the code in MainActivity:
using Android.App;
using Android.OS;
using Android.Support.V7.App;
using Android.Runtime;
using Android.Widget;
using Com.Squareup.Picasso;
namespace App3
{
[Activity(Label = "#string/app_name", Theme = "#style/AppTheme", MainLauncher = true)]
public class MainActivity : AppCompatActivity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
Xamarin.Essentials.Platform.Init(this, savedInstanceState);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.activity_main);
/***********************************************************************/
/**Picasso Code**/
ImageView imageView = FindViewById<ImageView>(Resource.Id.imageView1);
// Use the Picasso jar library to load and display this image:
Picasso.With(this)
.Load("http://i.imgur.com/DvpvklR.jpg")
.Into(imageView);
/**End Ff Picasso Code**/
/***********************************************************************/
}
public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
{
Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
}
XML Code:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:minWidth="25px"
android:minHeight="25px">
<ImageView
android:src="#drawable/icon" <!-- this line -->
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/imageView1" />
</LinearLayout>
The app does nothing, and in the emulator, the ImageView is empty.
And there is no error, or anything.
If you need anything more, please let me know.
I hope you can help me, if not, thank you for your time.
Edit 1:
It seems, the problem lies in the C# code.
If I add the android:src field, it still does not show up on the emulator, but when I remove the code (the Picasso code) than the image(drawable/icon) shows. Still no error!!
try this
<ImageView
android:src="#drawable/icon" <!-- this line -->
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minWidth="50px"
android:minHeight="50px"
android:id="#+id/imageView1" />
This question already has an answer here:
android webview causing null pointer
(1 answer)
Closed 7 years ago.
I've reduced my application to an almost dumb state trying to figure out the issue. I'm using the AndroidStudio (IntelliJ version) for development. I've been developing just fine until just recently the application started crashing before launching it seemed. Logcat showed this:
NullPointerException: Attempt to invoke virtual method
'void android.webkit.WebView.loadUrl(java.lang.String)'
on a null object reference
As stated I've reduced the application to an almost pathetic state. (No services, No receivers), and here's my Activity.
#Override
protected void onCreate(Bundle savedInstanceState) {
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
super.onCreate(savedInstanceState);
browser = (WebView) findViewById(R.id.web_view);
browser.loadUrl("file:///android_asset/www/index.html");
}
The line calling the error is the "browser.loadUrl" file, and this has been working fine for the last few hours. Please note that "requestWindowFeature" must be called above super.onCreate or the application will crash.
Here's my activity (Also unedited) and my application is nothing but a webview anyway.
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_height="match_parent"
android:layout_width="match_parent"
tools:context=".MainActivity"
tools:ignore="MergeRootFrame">
<WebView
android:id="#+id/web_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</FrameLayout>
I'm a bit confused.
you missed setContentView(int layoutId). Without calling it your Activity has no widgets to look for, and findViewById returns null
You need to add setContentView() in onCreate() method for Activity.
After setting up content view, find reference of id will be get in Activity.
#Override
protected void onCreate(Bundle savedInstanceState) {
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
super.onCreate(savedInstanceState);
setContentView(R.layout.<YOUR_LAYOUT_ID>);
browser = (WebView) findViewById(R.id.web_view);
browser.loadUrl("file:///android_asset/www/index.html");
}
I'm trying to add ActionBar-PushToRefresh to my project. I've followed the instructions from Chris Banes Github there: Github ActionBar-PullToRefresh
Here is my view from which I want to enable the PullToRefresh feature:
<uk.co.senab.actionbarpulltorefresh.library.PullToRefreshLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/ptr_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- Your content, here we're using a ScrollView -->
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="PULLTOREFRESH THE VIEW"
android:id="#+id/textView1" />
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
</ScrollView>
</uk.co.senab.actionbarpulltorefresh.library.PullToRefreshLayout>
And here is my Activity to display the view:
package com.Test.pulltorefresh;
import android.app.Activity;
import android.os.Bundle;
import uk.co.senab.actionbarpulltorefresh.library.ActionBarPullToRefresh;
import uk.co.senab.actionbarpulltorefresh.library.Options;
import uk.co.senab.actionbarpulltorefresh.library.PullToRefreshLayout;
public class MainActivity extends Activity {
private PullToRefreshLayout mPullToRefreshLayout;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Now find the PullToRefreshLayout to setup
mPullToRefreshLayout = (PullToRefreshLayout) findViewById(R.id.ptr_layout);
// Now setup the PullToRefreshLayout
ActionBarPullToRefresh.from(this)
// Mark All Children as pullable
.allChildrenArePullable()
// Set the OnRefreshListener
//.listener(this)
// Finally commit the setup to our PullToRefreshLayout
.setup(mPullToRefreshLayout);
}
}
When I launch my app, I got the blank view but nothing happens when I'm trying to PushToRefresh my view. Can someone show me how to fix it, I know that I've missed something. Thanks.
I may be a bit partial but...
you could consider using this
Maybe you have already achieved the functionality, but in the code above, you have commented out the line which defines the action on pulling the view.
//.listener(this)
You should uncomment this line and define the listener method, which should be called when the view is pulled.
The following classes could not be instantiated:
- com.amazon.device.ads.AdLayout (Open Class, Show Error Log)
See the Error Log (Window > Show View) for more details.
Tip: Use View.isInEditMode() in your custom views to skip code when shown in Eclipse
java.lang.NoClassDefFoundError: Could not initialize class android.os.Environment
at com.amazon.device.ads.DebugProperties.readDebugProperties(DebugProperties.java:75)
at com.amazon.device.ads.InternalAdRegistration.<init>(InternalAdRegistration.java:52)
at com.amazon.device.ads.InternalAdRegistration.getInstance(InternalAdRegistration.java:64)
at com.amazon.device.ads.AdLayout.initialize(AdLayout.java:185)
at com.amazon.device.ads.AdLayout.initialize(AdLayout.java:176)
at com.amazon.device.ads.AdLayout.<init>(AdLayout.java:120)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0( at sun.reflect.NativeConstructorAccessorImpl.newInstance( at sun.reflect.DelegatingConstructorAccessorImpl.newInstance( at java.lang.reflect.Constructor.newInstance( at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass(ProjectCallback.java:422)
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView(ProjectCallback.java:179)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:207)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:135)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:755)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:727)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:373)
My main.xml looks like this
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:Amazon="http://schemas.android.com/apk/lib/com.amazon.device.ads"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="top|center_horizontal" >
<com.amazon.device.ads.AdLayout
android:id="#+id/myAdView"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<ScrollView
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
My MainActivity.java is this
import com.amazon.device.ads.AdLayout;
import com.amazon.device.ads.AdRegistration;
import com.amazon.device.ads.AdTargetingOptions;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
preferences = PreferenceManager.getDefaultSharedPreferences(this);
int defaultValue = R.drawable.blue;
int themedefault = ThemeChanger.THEME_BLUE;
appliedtheme = preferences.getInt("mytheme", themedefault);
ThemeChanger.onActivityCreateSetTheme(this, appliedtheme);
setContentView(R.layout.main);
AdRegistration.setAppKey("Application_Key");
this.adView = (AdLayout) findViewById(R.id.myAdView);
this.adView.loadAd(new AdTargetingOptions());
button1 = preferences.getInt("DigitButtonStyle", defaultValue);
buttonmadd = preferences.getInt("MemoryButtonStyle", defaultValue);
buttoncos = preferences.getInt("FunctionButtonStyle", defaultValue);
I had the same issue and followed Amazon developer guide. To solve this issue, just copy amazon library and paste it in your libs folder and than run.
It's a known issue in Eclipse ADT plugin, even if you use View.isInEditMode(), in some cases, it crashes in recent API versions (higher than 18). It's fixed in Android Studio.
If you want to see Layout Preview, you can try with different API version lower than 19.
Check the screenshot. It's using API 18. (Red box is Amazon AdLayout)