Do one thing, the jsps are compiled into java servlets, so you can check the code and see at the appropriate line. The java files are I guess in work directory of tomcat. Line of error org.apache.jsp.index_jsp._jspInit(index_jsp.java:22) Here is the file to look at. index_jsp.java solved getting org.apache.jasper.JasperException: java.lang.NullPointerException
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
To understand the difference, it always helps to read out your condition statement in english. if ( !name.equals(“abc”) || !name.equals(“cba”) ) Translates to If name does not equal “abc” OR name does not equal “cba”, then… Whereas, if ((!(name.equals(“abc”) || name.equals(“cba”) ))) If (name equals “abc’ OR name equals “cba” ) IS FALSE, then… or, … Read more
base becoming multiplied by 5 got lost in the second version. public static int trailingZeroesV2(int n) { return trailingZeroesV2(n, 5); } private static int trailingZeroesRec(int n, int base) { return n == 0 ? 0 : n / base + trailingZeroesRec(n / 5, base * 5); } (Typically a recursive function uses an extra parameter,) … Read more
Every thread in a Java program must have an associated Thread instance, and every Thread “has” a Runnable.* There’s no way around it. It’s just how Java works. You can call Thread.currentThread() from anywhere in your program and it will always return a reference to the Thread object that controls the thread that is executing … Read more
quote | space || ——-+——-++—– 0 | 0 || ^[a-z]*$ 0 | 1 || ^[a-z]* [a-z]*$ 1 | 0 || ^[a-z]*'[a-z]*$ 1 | 1 || ^[a-z]* [a-z]*'[a-z]*$ or ^[a-z]*'[a-z]* [a-z]*$ Eg. final Pattern regex = Pattern .compile(“^([a-z]*|[a-z]* [a-z]*|[a-z]*'[a-z]*|[a-z]* [a-z]*'[a-z]*|[a-z]*'[a-z]* [a-z]*)$”, CASE_INSENSITIVE); for(String x: asList(“”, “‘”, ” “, “‘ ‘”, ” a “, “p%q”, “aB cd’Ef”, … Read more
If you want to keep the following variables outside main method, declare them with static keyword as follows: static Statement stmt; static ResultSet rs; Alternatively, place them as they are inside main method. 1 solved “Non-static variable cannot be referenced…” in my main method? [duplicate]
You are creating a method inside method which is not allowed Create Outside of OnCreate() public class MainClock extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main_clock); } public void newPacket(View view) { Intent intent = new Intent(this, NewPacket.class); startActivity(intent); } } 2 solved Cannot resolve symbol view – Android Studio [duplicate]
Check Regex and Substring For your example it would be something like public boolean isValid(String h) { return h.substring(1).matches(“^[A-H0-9]+$”); } 2 solved Check the characters of a string
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
what about anonymous classes like new Ab(2,4); This is not an anonymous class. It’s an expression that creates a new object of type AB. The value of that expression is a reference to the object. The value of this within the AB constructor is a reference to the object. And the value of x below … Read more
This is how you can iterate over your Map: for (Map.Entry<String, Integer> entry : killstreaks.entrySet()) { String key = entry.getKey(); Integer value = entry.getValue(); // continue here } To get a specific value (Integer) from your Map use: killstreak.get(“yourKey”); Seeing from your comment that you want to increment entries by 1, you can use: killstreaks.put(key, … Read more
Your static block is off, and you’re missing any import(s). Java doesn’t have a named dictionary parameter syntax, it should look something like private static Set<Book> books; // do not use raw-types static { books = new HashSet<>(); // diamond operator books.add(new Book(1, “C++”, 10, “ABC”)); // need to close the .add() call books.add(new Book(2, … Read more
I found the answer to my question. Field field = this.getClass().getDeclaredField(nameOfField); return (Double) field.get(this); solved Is there a shorter way to write this code, without repeating three times switch?
Try this public static void s() { System.out.println(s); s–; if(s!=0) { //I want the program to stop here since s is already 0. System.out.println(s); } } 1 solved Java exit while loop from called method [duplicate]