Since JSR 305 (whose goal was to standardize @NonNull and @Nullable) has been dormant for several years, I’m afraid there is no good answer. All we can do is to find a pragmatic solution and mine is as follows: Syntax From a purely stylistic standpoint I would like to avoid any reference to IDE, framework … Read more
findViewById() returns a View if it exists in the layout you provided in setContentView(), otherwise it returns null and that’s what happening to you. Note that if you don’t setContentView(), and don’t have a valid view to findViewById() on, findViewById() will always return null until you call setContentView(). This also means variables in the top-level … Read more
The tutorial is probably outdated, attempting to create an activity-based UI instead of the fragment-based UI preferred by wizard-generated code. The view is in the fragment layout (fragment_main.xml) and not in the activity layout (activity_main.xml). onCreate() is too early in the lifecycle to find it in the activity view hierarchy, and a null is returned. … Read more
First of all, change this line : image = ImageIO.read(getClass().getClassLoader().getResource(“resources/icon.gif”)); to this : image = ImageIO.read(getClass().getResource(“/resources/icon.gif”)); More info, on as to where lies the difference between the two approaches, can be found on this thread – Different ways of loading a Resource For Eclipse: How to add Images to your Resource Folder in the Project … Read more
The field annotated @Autowired is null because Spring doesn’t know about the copy of MileageFeeCalculator that you created with new and didn’t know to autowire it. The Spring Inversion of Control (IoC) container has three main logical components: a registry (called the ApplicationContext) of components (beans) that are available to be used by the application, … Read more
When you declare a reference variable (i.e., an object), you are really creating a pointer to an object. Consider the following code where you declare a variable of primitive type int: int x; x = 10; In this example, the variable x is an int and Java will initialize it to 0 for you. When … Read more
Avoiding NullPointerException in Java
I will suggest to Override onActivityCreated method : @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_home, container, false); return view; } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); images = (ImageView) view.findViewById(R.id.complaint_posted); images.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent intent=new Intent(getActivity(), DetailPost.class); startActivity(intent); } }); } … Read more
<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=”bd2c.bd2c_appdemo.MainActivity”> <TextView android:id=”@+id/principal” android:layout_width=”wrap_content” android:layout_height=”wrap_content” android:text=”@string/app_text” /> </RelativeLayout> This is your fixed layout select all copy that and go to your layout select all and paste this. Bingo 🙂
You shouldn’t be setting the onClickListener for your button within the button itself, instead it should be set in the Activity that makes use of both of your buttons. Likewise, findViewById() in your example can’t find the TextView as it’s not within the same scope as your button. In absence of code from your activity, … Read more