You need to initialize your button, you are calling OnClickListener on null reference LoginButton =(Button)findViewById(R.id.button_login); Before calling LoginButton.setOnClickListener() initilize your login button. 6 solved Null object reference error when trying to open new activity on Android? [duplicate]
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
DetailActivity is just that, an Activity. You cannot access methods in it as you would an object. The only way to do so is to make that method static and do DetailActivity.showHtml() but this is not recommended. The other problem is that you are not creating that Activity properly. You need to start it as … Read more
It’s because the contract for the equals method, as specified in the Javadoc for the Object.equals method , explicitly states: For any non-null reference value x, x.equals(null) should return false. If the method threw a NullPointerException, it would be non-compliant with the contract. solved Why doesn’t equals throw NullPointerException when one of the variables is … Read more
You are not passing the array object to sort method. Try the following code: public class SortTest { public void sort(String[] array) { String insert; for (int next = 1; next < array.length; next++) { insert = array[next]; int moveItem = next; while (moveItem > 0 && array[moveItem – 1].compareTo(insert) > 0) { array[moveItem] = … Read more
Variable next is null when you call next.setOnClickListener() probably R.id.prosseguir is a wrong identifier solved The function is not working and is making the program crash when I start the Activity [duplicate]
<view android:layout_width=”1dp” android:layout_height=”match_parent” android:layout_marginTop=”16dp” android:background=”@android:color/darker_gray” /> Change view with View 2 solved I can’t run my app (android studio) [duplicate]
Try this.Assuming the variable albumList is global. and albumList is not null; final int speedScroll = 1000; final Handler handler = new Handler(); final Runnable runnable = new Runnable() { int count = 0; @Override public void run() { if(count == albumList.size()) count =0; if(count < albumList.size()){ recyclerView4.smoothScrollToPosition(++count); handler.postDelayed(this,speedScroll); } } }; handler.postDelayed(runnable,speedScroll); } @Override … Read more
Line 46 is; actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST); The only thing that can be null on here is actionBar, therefore getActionBar() is returning null, the reasons for this; getActionBar() returns null – Title bar isn’t visible. getActionBar returns null – You must request an action bar using getWindow().requestFeature(Window.FEATURE_ACTION_BAR);, you may think your info bar is an action bar. etc. … Read more
Attempt to invoke virtual method ‘void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)’ on a null object reference solved Attempt to invoke virtual method ‘void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)’ on a null object reference
Problem is in the actionPerformed() method. The class variable patient is null. You can do a null check like this… public void actionPerformed(ActionEvent e) { if(e.getSource() == reportButton && patient != null) { System.out.println(“I’m Clicked!”); patient.setAge(ageField, log); } } Or you can initalize the variable… public void actionPerformed(ActionEvent e) { if (patient == null) { … Read more
That loop only goes to 4 for i, so you don’t end up inserting anything when you change the conditon to i == 5. 1 solved Why am i NOT getting null pointer exception in this case while adding null to a list and sorting it
If that line is throwing a NullPointerException, it must be that textView is null. This is probably because your findViewById call gave an id which was not found in the view. You haven’t given us enough information to be sure, but I suspect you’re trying to grab a textView in the helpDialog you just showed. … Read more
Firstly, your MediaPlayer instance should reside within MainActivity, not MyListener, and MyListener should not extend an activity. In fact, you should move all of your code from MyListener into MainActivity, I don’t really see a purpose for it in the snippet you’ve provided. Secondly, You’re creating your MediaPlayer outside of the Activity Lifecycle, while still … Read more
I did not understand how the output you showed has one of the numbers multiplied by 100 in each element of String array. Based on my understanding of your question here is a solution. import java.util.Arrays; import java.util.Collections; import java.util.LinkedList; import java.util.stream.Collectors; import java.util.stream.IntStream; public class Shifts { public static void main(String[] args) { LinkedList<Integer> … Read more