I am confused with the following function signature in the class java.util.Collections.
static <T> boolean replaceAll(List<T> l, T oldValue, T newValue);
I got the other parts but i could not figure out at all what is the meaning of <T> in the beginning.
The Iteratior provides the functionality of traversing and removal which we can achieve through normal for loop and remove() of the data structure.Then, why do we need Iterator explicitly and as an inner class?
View Replies View RelatedI am trying to create a java program to sort an array in ascending and descending order. Here is the program I created :
import java.util.Arrays;
import java.util.Collections;
public class ArraySort
{
public static void main(String [] args) {
int [] num = {5,9,1,65,7,8,9};
Arrays.sort(num);
[Code]...
BUT I GET THE FOLLOWING EROOR ON COMPILATION
ArraySort.java:12: error: no suitable method found for reverseOrder(int[])
Arrays.sort(num,Collections.reverseOrder(num));
^
method Collections.<T#1>reverseOrder(Comparator<T#1>) is not applicable
[Code] .....
What's wrong with my program?
In Java code, write class called Student with the following features:
• a private instance variable int studentNumber that is initialized to zero.
• a private instance variable String firstName;
• a private instance variable String lastName;
• a constructor which takes an integer argument and two String arguments to initializes the three respective data items.
• a public method with signature equals(Student s) . . .
So far this is my code :
public class student {
private int studentnumber = 0;
public student () {
firstname= "forename":
lastname="surname":
public student (integer studentnumber, string firstname, string lastname) {
this.firstname= firstname
this.lastname= lastname:
My question is how do i add the integer in the argument do i have to use int =? and how would i go about doing the public signature equals...
I must apply a electronic signature to a predefined XML.
File looks like this:
<xml....
<invoice serialCode="NT" serialNumber="123" issueDate="2014-10-01" startDate="2014-09-01" endDate="2014-09-30" orgUnitCode="CAS-NT" providerCode="15107618" providerCategory="PARA" contractNumber="8207" contractType="PAR" contractDate="2014-06-27" totalAmmount="34.81"
And at the end there is a sinature that looks like this:
‚ R0‚ N0‚ 6 $P Gæ&"ùO]ó]0
*†H†÷
0h1%0# U DigiSign Qualified Public CA1 0 U DigiSign Public CA1 0 U
DigiSign S.A1 0 U RO0
140722065817Z
[Code] ....
How can I do this in java?
I have a linked list of objects of a class I created called BaseballPlayer. I also have a Fielder and Pitcher class that extends BaseballPlayer. The linked list and list nodes accept elements of type BaseballPlayer. I put into the linked list both Fielder objects and Pitcher objects. The Pitcher class has a method that returns a float variable that is only found in the Pitcher class called EarnedRunAverage. However, in my main program it won't let me access the method. It says: The method getERavg() is undefined for the type BaseballPlayer. It does however, let me access methods in the super-class BaseballPlayer.
Here is main code and the Pitcher class code.
ListNode p = list.getFirst().next;
while(p!=null){
if(p.player instanceof Fielder){
sortedFielders.append(Integer.toString(p.player.getNum()) +',');
[Code]....
I would use the return value of a function how parameter of other function..In java is:
// the call produce "YES"
SecondClassController.funcSecondClass(FirstClassController.funcFirstClass());
In my web page I need to do something like this:
[...]
<h:outputText value="#{secondClassController.funcSecondClass(#{firstClassController.funcFirstClass()})}" />
[...]
obtain:
javax.servlet.ServletException JBWEB006007: Failed to parse the expression
@Named
@SessionScoped
public class FirstClassController implements Serializable{
[...]
[code]....
I am new in Collection, as per my knowledge I have already override the hashCode() and Equals() method in Data class, but when I trying to search the element it is giving "not found". find the bug.
import java.util.*;
public class WordCounter {
public static void main(String args[])
{
HashSet<Data> set=new HashSet<Data>();
set.add(new Data("this",2));
[code]....
I am just not sure of some theory in collections, ArrayList and LinkedList maximum capacity depends on the memory allocated to the JVM. But according to few people those list has a maximum capacity of Integer.MAX_VALUE.
According to my experiment, those list has a maximum capacity of Integer.MAX_VALUE since the get method of List accept a parameter of int primitive type (index of element), therefore we can conclude that the maximum capacity of List is equal to Integer.MAX_VALUE.
But what about the Map? get() method of map accepts object(the key of the map). So does it mean that the maximum capacity of Map depends on the memory allocated to our JVM? Or its maximum size is Integer.MAX_VALUE also just like Lists and Arrays? Is there a way to prove it? Is Map designed to hold infinite number of data (disregarding the heap memory space exception)?
And also about Stack, Deque? is it also the same as Map (in terms of maximum capacity)?
Today I installed jdk1.8.0_20 on my computer and typed a simple example code in MyEclipse 6.0 IDE, the code listed below:
import java.util.List;
public class Test5
{
public static void main(String[] args)
{
List<String> features = Arrays.asList("Lambdas", "Default Method", "Stream API", "Date and Time API");
features.forEach(n -> System.out.println(n));
}
}
the MyEclipse Editor shows some errors like "Arrays can not be resolved" and "n can not be resolved".
I did use jdk 8 in the build path, but it seems like the jdk 8 did not function properly.
I am using this image as a reference to learn the Collection interface better and it seems I must be getting confused with the 'ordered/unordered' types. I thought ordered would mean ordering the objects automatically like a TreeSet using the comparable interface so it could be numerically or alphabetically ordered etc..
Java Code:
public static void main(String[] args) {
Set hashSet = new HashSet();
hashSet.add(1);
hashSet.add(3);
hashSet.add(2);
for (Object o : hashSet){
System.out.print(o + " "); // Prints: 1,2,3 (Unordered but puts the numbers in order....)
[code]...
When I run my code, I get an error with this line
if(Collections.binsearch(dict, word3) != -1) {
I imported the collections utility and everything. Tell me if you need to see more of the code. The exact error is binsearch is undefined for the type Collections.
I have a method that draws a polygon on the screen:
public void poly(List<Point> points) {
//code
}
For the usage of the method, it makes no difference whether points is an array or a List. In fact, switching doesn't even change any of the code in the method since I use a for-each loop. So, my question is, is it a better practice to use a List as an argument, or an array when the method itself doesn't care about which to use?
I have searched on internet but did not find something useful. I do not want to use collections. here's what i have written
class ArrayDemo3
{
static void union(int x[], int y[])
{
System.out.println("Union Elements:");
for(int i=0; i<x.length; i++)
{
for(int j=0; j<y.length; j++)
[code]....
I'm doubted regarding the implementation of Collections.binarySearch() method on an ArrayList of objects of a custom class Movie.
Here is the movie class :
public class Movie implements Comparable<Movie> {
String movieName;
String rating;
String director;
String theme;
[Code] .....
The sort/binarySearch in searchByMovieName function is done with natural sorting (and Comparable Interface in Movie class). I mean no comparators involved here. And the comparator that I used for sorting/binarySearching on Movies Director attribute in searchByMovieDirector function is :
public class MovieDirectorComparator implements Comparator<Movie> {
public int compare(Movie movie1, Movie movie2) {
return movie1.getDirector().compareToIgnoreCase(movie2.getDirector());
}
}
But I was not able to implement binarySearch ?? How to implement the binarySearch here. I have google to see only binarySearch working on Arrays or probably ArrayList of String only, but not on ArrayList of custom objects.
My friends and me are trying to make online Test taking system. We got a very basic doubt.
We have developed classes and relationship between classes for example : Online Test Taking system will have admin and student class. And Admin will have list of students.. etc.
But question troubled me was: if we use database to store all data for example student details then I can perform all sorts of operations writing sql query and store result in some other database then what is the need of "ArrayList<Student> field in Admin".??
Question is: We can put everything in database and manipulate using database(sql) functions to manipulate it.Then what is the need of Arraylist of anything which is just used to store object details for example student details....??
my first assignment is to convert a md5 string to password of the user, the MD5 function is available, i just need to call it and print the result. Here is my code. I can't call the md5 because of the String[] and String is different in main and md5 function,modify the code so it can run properly, also the input has to be entered from command line.
import java.security.*;
public class PasswordCracker {
public static void main (String[] args){
String password;
md5(args)
System.out.printf(""+password+"");
[code]....
I'm trying to create a booklist in java using swings but I'm facing a problem. I don't know how to add a search function to my list. I need a search box with the book names.
View Replies View Relatedwhere I have to write a Java program that asks for user input regarding a book and provides information based on that input like the number of pages required, number of words on the final page and if the final page is more than half full, etc. We are told that each page should have 250 words maximum to use for our calculations. The problem I am having here is that when the total number of words is a multiple of 250 the output tells me that there are 0 words on the last page when in fact there are 250. I've tried messing around with mod functions in this format ((x+a)%250)+y which is what the professor told us to use instead of creating an if-statement for this case but I haven't been able to crack it. I don't think I fully understand how the mod function cycle could work for this case.
import javax.swing.JOptionPane;
public class CorreiaFranciscaA1Q1 {
public static void main(String[] args) {
String ManuscriptTitle =
JOptionPane.showInputDialog ("Please enter a book title.");
String AuthorName =
JOptionPane.showInputDialog ("Please enter the author name.");
String TotalWords =
JOptionPane.showInputDialog ("Please enter the number of words.");
[code]....
Above if totalWords is a multiple of 250 like 17500 then wordsFinalPage will give us 0 and I need it to give 250. How can I do that without using an if statement but instead using a mod function?
Using JPA 2.1, I have been trying without luck to call a function that returns a REF CURSOR containing RECORD TYPES. Is there a way of doing this?
One Example of trying:
Query query = em.createNativeQuery("select my_package.my_function from dual");
Object a = query.getSingleResult();
I have also tried to use the StoredProcedureQuery though this does not look like it can return the functions value.
Produced
org.springframework.orm.jpa.JpaSystemException: No Dialect mapping for JDBC type: -10;
nested exception is org.hibernate.MappingException: No Dialect mapping for JDBC type: -10
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:244)
[Code] ....
I just wanted to ask that when we invoke a function by passing certain arguments in it ,so for instance I have certain variables like a,b and c with some values assigned to them,so when I invoke a function like func(a*b , 8, c+a) where the function func accepts parameters like func(int x,int y,int z) ,so is there any order of evaluation of expressions defined like the value of c+d would be evaluated first and then assigned to variable z ,because in C we have sequence points and since comma when acting like a separator is not a sequence point so any of the expression can be executed first ,so basically is there any sequence in which the function arguments are assigned to the parameters of the function or any relation with the stack implementation.
Even in C ,the printf starts executing its expressions from right to left so basically in why does it happen there when comma is a separator in a function argument.
E.g:
onblurr="check(this, '<%=company.getId()%>' );return false;"
doing this, function check(field, inputVal) {
alert("companyId:" + inputVal);
}
Gave me the alerted value as :
companyId:<%=company.getId()%>
instead, if the company.getId() --> 30
When I do like this, how to get the value 30 inside the function? i want companyId:30
I want to test that a function has no any exceptions.In C++ and Google Test Framework (GTest) it will look like this:
ASSERT_NO_THROW({
actual = divide(a, b);
});
How will it look in Java?
In JSP page: firstly set the setter of a entity in bean and then set it in session,request etc. and gvet values using foreach loop as follow :
<jsp:useBean id="st" class="beans.student">
<jsp:setProperty name="st" property="roll_no"/>
</jsp:useBean>
<%
[Code]....
Here start is the variable whose value will vary after every time i visit this function.So how would i be able to use above query.
P.S. i was using scriplet before and i was able to deal these issues with scriplet easily.
So I have this
function checkvalue (val) {
if(val==='replaced')
document.getElementById('check1h').style.display='block';
else if (val==='checked')
document.getElementById('check1h').style.display='none';
else
document.getElementById('check1h').style.display='none';
}
Which works fine... But if I try and add another document under the if VAL === replaced then nothing works and neither of the boxes appear.
function checkvalue (val) {
if(val==='replaced')
document.getElementById('check1h').style.display='block';
document.getElementById('check1n').style.display='block';
else if (val==='checked')
document.getElementById('check1h').style.display='none';
else
document.getElementById('check1h').style.display='none';
}
Is this not possible?
Also, Both of my input type are set up like this...
<input type='text' style='display:none' name='check1n' id='check1n' placeholder='Name of Part' />
<br>
<input type='text' style='display:none' name ='check1h' id='check1h' placeholder='Part Number' />
I am new to java. I have written a function in C#,how can i convert it into Java.
public AsymmetricKey readKey(String filename)
{
StreamReader reader = new StreamReader(filename);
String modulus64 = reader.readLine();
String exponent64 = reader.readLine();
byte[] modulusBytes = base64Decode(modulus64);
byte[] exponentBytes = base64Decode(exponent64);
BigInteger modulus = new BigInteger(modulusBytes);
BigInteger exponent = new BigInteger(exponentBytes);
AsymmetricKey key = new AsymmetricKey(modulus, exponent);
[code]....