I have a java code that should sort an array of names based on the last name. e.g jane a, jane b, jane z, jane d should be jane a, jane b, jane d, jane z. I have the following code but for some reasons, the s1 in the comparator method is always null.
public class ShuffleName {
public static void sortNames(String[] names){
Arrays.sort( names, new Comparator<String>() {
public int compare( String s1, String s2 ) {
String s1last = s1.split("s+")[1];
String s2last = s2.split("s+")[1];
return s1last.compareTo(s2last);
I am trying to use the JList to display a list of students. Now, each student has a first name, last name and course taken. each courses taken by the student has its' own name, level and idNumber. For now, I am just trying to create my own custom JList model for the students. I have the custom model as well as the button event calling it. Unfortunately, when I click the button to display the student info added, the component is NOT fired up!..
I am not sure what I have done wrong regarding creating the component because I can display the information on the console and the list contains everything I have added but just to display it on the component is NOT working. I have broken the codes into sub classes, you can add the classes to the same package or create sub packages to insert individual classes.
The student class
public class Student { private String studentName; private String studentID ; public String getStudentName(){ return studentName;
I have a custom library I made to make things easier for myself. I used it in a small program in NetBeans and it works fine. When I try to clean and build, it says it can't find the methods from my Library class. How do I get the library packaged into the jar?
I am trying to use a custom listener to initialize database connection pool (C3P0) on start up and then destroy on context shut down. The reason for that is that I whenever context is shutdown I have a memory leak because initialized connection pool is not being destroyed.
I have a static class called C3P0Utils that deals with connection pool. In my listener in contextInitialized method I have tried at first to init the pool like this :
I know that object is created. I checked it using jconsole. However it is not accessible with in the application. My second attempt was to regester the pool and then add it to the context and then when I need it read from there.
have to create a file named Lab13.txt. In the file I have 10 random numbers. I have to import the 10 numbers and have to Multiply all the numbers from Lab13.txt by 10 and save all the new numbers a new file named Lab13_scale.txt. so if the number 10 is in lab13.txt it prints 100 to Lab13_scale.txt. how do i get it to Multiply Here is what I have:
I have a project where I am required to read and write a vector of bank account objects and I am struggling with this concept. I was able to figure it out when the accounts were not stored in a vector but now that I am dealing with vectorsThis is my best attempt. Even though I know it's wrong, what I am trying to do.write/read methods in main:
public static void readTrans() { textArea.setText(""); chooseFile(1); try { FileInputStream fis = new FileInputStream(filename); ObjectInputStream in = new ObjectInputStream(fis); for (int index=0; index != fileIndex; index++)
I am trying to sort an ArrayList of objects with the comparator as I want to sort based on a certain value for each object. I understand I would need to override compareTo() in the objects class, is there any way I can get around also needing to override for all subclasses of the object?
I am asked to create a code that if a user enters 1 it will use the object natural comparison form ('default') as written in CompareTo method.But if he chooses to enter something else then another comparison is used.Maybe I just need to use 2 diff comparators? but then what;s the point of defining something as 'default'....
I am currently working on a java project, this involves me writing some code for a project, below are my attempts at coding so far:
/** * Prints out details of all animal in the zoo. * */ public void printAllAnimals() { System.out.println(" Details for all animals in Zoo " + zooId); System.out.println( "==================================");
[code]....
I currently cannot get the printallanimals() method to work as it should when executing the method printallanimals it just opens a filedialog box, when it is suppose to use the Collection object c,so that animals stored in the zoo can easily be checked.
I'm doing this assignment in which i have to write some products in csv file...but as u can see in csv file two products are same "Cooking Oil"..so any method that can add two same product's quantity and their amount and write them in file
import java.util.*; import java.io.*; public class SalesbyTransactionMonth{ private static final String fileName = "Data.txt"; private static final String fileName1 = "sales_by_trans_month.csv"; String line = "";
I have a big problem with writing Gauss Elimination in Java code. This is my homework, it's true. But I want to learn this, and I don't know how to bite this. I must realise some points:
1) Create new class - Gauss Elimination with two attributes (table A (nxn) and table B with vector (n));
2) Add new method "eliminate" which transform matrix A and parametr vectors B ;
3) Add new method "solve" which calculate inverse substitution.
I want to print data on invoice receipt size of 20.5 x 14 cm(hard copy). In which I try to put text at some absolute location. I tried iText first. In that I try to set page size by following code. here what is unite used in bracket of rectangle?
Document document = new Document(new Rectangle(552,377)); PdfWriter.getInstance(document, new FileOutputStream("report.pdf")); document.open(); ... ... ... document.close();
Second I tried Jasper report. In that I set page size to 20.5 x 14 cm. But how can I take value from my java application's textfield and put it in to some absolute location in iReport.As I know jasper report take value from database but how can I take value from java application's textfiled?
I am more familiar with iText. How can I print custom invoice using iText or Jasper Report.I am developing java application using netbeans.
public class Someone { String name; int age; ArrayList <Someone> listarr = new ArrayList <Someone>(); public Someone(String name1, int age1) { name = name1; age = age1;
[code]...
1. In the compare method, what happens when it returns one of the 0, -1, or 1? How does returning such values contribute to the sorting process? How does it take in information (like I know it does through the parameters, but how exactly)?
Something about implementing Comparator interface isn't very clear to me: overriding the compare method.
Like here for example:
//This sorts a list of objects holding information based on age: the name and the age of the person
public class Person { String name; int age; public Person (String name, int age) { this.name = name; this.age = age;
[Code] ....
What exactly is happening behind the scenes? I don't understand mostly the part where it returns a 0, a 1, or a -1. After it returns one of those values, what really happens next?
For the displaying of the list, is the method toString() being accessed to output the list in the System.out.println statement?
If an array has been sorted using a comparator then why is it necessary to pass on that comparator to the binaryserach method. What I want to know is that how come the presence of a comparator reference affect the way the algorithm works?
Which of the following classes uses Comparable and Comparator?
QueueTreeSetStackPriorityQueue
In the above question, what does 'uses' mean? Does it mean do above classes implement Comparable and Comparator?
I know that in order to compare any two elements stored in one of the above classes, we need to make the elements' class to implement one of these - either Comparable or Comparator.
calculate how long it would take to pay off a loan of 500 pounds if there was 10% interest monthly, and 100 pounds was paid each month. This code is in a pseudocode,
set months = 1 set balance = 500 set totalpaid = 0; while balance > 100 balance = balance - 100; set interest = balance * 0.1 balance = balance + interest totalpaid = totalpaid + 100 months = months + 1 endwhile totalpaid = totalpaid+balance display "you paid "+totalpaid display "It took you "+months+" months"
So I built this comparator exactly the same way I built my others that are working.But the comparator for UserComparator is not being found for some reason.I will post my usercomparator class and JSP page.
The initial output of the texfile is this. NO ARRAYLIST OR COMPARATOR IS ALLOWED:
Steve Jobs 9 f 91 Bill Gates 6 m 90 James Gosling 3 m 100 James Gosling 3 f 100 Dennis Ritchie 5 m 94 Steve Jobs 9 m 95 Dennis Ritchie 5 f 100 Jeff Dean 7 m 100 Bill Gates 6 f 96 Jeff Dean 7 f 100 Sergey Brin 27 f 97 Sergey Brin 22 m 98
The collateExams method collates/sorts exam objects starting with the first 'm' (midterm) of the first object and immediately followed by the same person's 'f'(final). Only a SINGLE loop construct is allowed. The output from collateExams() should be the one below but my code is not working, i.e. collateExams method is not working. The output from collateExams() should be
Bill Gates 6 m 90 Bill Gates 6 f 96 James Gosling 3 m 100 James Gosling 3 f 100 Dennis Ritchie 5 m 94 Dennis Ritchie 5 f 100 Steve Jobs 9 m 95 Steve Jobs 9 f 91 Jeff Dean 7 m 100 Jeff Dean 7 f 100 Sergey Brin 22 m 98 Sergey Brin 27 f 97
I am getting [b]NullExceptions[/b] at
r[2*position[exams[i].getID()]+1] = new Exam(r[i].getFirstName(), r[i].getLastName(), r[i].getID(), r[i].getExamType(), r[i].getScore());
i have to write more than 100000 rows in a excel sheet (file size more than 20 MB) via java.
when i use XSSF, i am getting below Error.
java.lang.OutOfMemoryError: Java heap space at org.apache.xmlbeans.impl.store.Saver$TextSaver.resize(Saver.java:1592) at org.apache.xmlbeans.impl.store.Saver$TextSaver.preEmit(Saver.java:1223) at org.apache.xmlbeans.impl.store.Saver$TextSaver.emit(Saver.java:1144)
[Code]....
when i use HSSF , i am getting the below Error. java.lang.OutOfMemoryError: Java heap space
I have tried increasing the java heap size , by giving upto -Xms1500m -Xmx2048m
