I started learning JSTL (Java Standard Tag Library) and i got to know that i need to mention this directive in JSP page
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
in order to use JSTL tags.
I am not able to understand what does this URI exists at all ?? I feel it making things complex and meaningless or else i am missing something hidden and secret.
Netbeans tells me it's an illegal start of expression during the initialisation of the interactWithUser method.
public class InvertLetter {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
/**
* String mit den Kleinbuchstaben.
*/
final String lowercase = "abcdefghijklmnopqrstuvwxyz";
[Code] ....
Let's say within a class I create a method that takes care of creating a java swing layout with labels, buttons etc.. then attach an action listener (inner class) for each button to change a respective label text. All I would need is that the action listener method can access and modify the label as needed.
Have read about static, protected, private, getters and setters but honestly bit confused about which structure should be adopted as a best practice. Global static protected variables for the labels along with private inner classes implementing ActionListeners believe will do the trick and will be able to access the labels but not convinced this is good practice.
My Question is Suppose I am declaring an String array as
String[] a
or
String a[]
or
Comparable[] a
Will there be any performance or other advantage or disadvantage using these syntax?
import java.util.HashSet;
import java.util.ArrayList;
public class Graph
{
double [] [] adj;
graph (double [] [] a)
{
adj= new double [a.length][a.length];
for (int i=0;i<a.length;i++)
for (int j=0;j<a.length;j++)
adj[i][j]=a[i][j];
}
C:UserscDesktopGraph.java:: error: invalid method declaration; return type required
graph (double [] [] a)
I tried this:
String[][]f = new String[1][1] {{"Harry"}{"Hairy"}};
I also tried this:
String[][]f = new String[1][1] {{"Harry"},{"Hairy"}};
but I get an error
Ok say you have
public class MyClass {
private int x = 5;
Object myObject = new Object();
public MyClass(){
}
}
When would the myObject be created? Before or after the constructor? And does this mean you can't pass
this into the parameters of that object?
I'm new to Java and have been stuck on how to use a final declaration statement once it's made. Below is a class I'm creating with the intention of calling it under a main method. I don't understand if I'm supposed to do anything else, like do some sort of get/set, or if the final static line is all I need. And, I don't know how I call it to the main method once I do.
public class Shirt//class name.
{
int collarSize;//data field.
int sleeveLength;//data field.
public final static String MATERIAL = "cotton";//final data field for material.
[Code] ....
Whilst pre-preparing for java certification, one of the online mock exams has slightly confused me by saying my answer was incorrect for multi-dimension array 'declaration and instantiation'.
This is one of the answers i chose - which was marked as incorrect
a)
int[][] array2d = {{123}, {4,5}};
Which looks absolutely fine to me.One of the other answers, which i agree is correct and so does the mock exam is
b)
int [][] array2d = new int[2][2];
when a new object is created in Java it follows the idiom:
Object obj = new Object();
where the Object() constructor matches the object type Object.
But what if it doesn't? I understand from the Oracle Docs on creating objects and polymorphism that the constructor must be in that object's class or one of its subclasses. However, suppose we wanted to declare a new stack. My first instinct would be:
Stack s1 = new Stack();
But I assume it's valid to do it this way, too:
Object s2 = new Stack(); // Is there a difference here? What are we really saying about s2? I'm guessing s2 is simply an empty stack, but only has access to the Object class methods? I'm not sure why someone would ever do this, but I want to solidify my understanding of the Java hierarchy. Are there really any circumstances where someone would use a subclass's constructor when creating a new object?
I have one interface with three(more than one) method declaration. In the subclass that implements it I want to define only one method not all three not even blank definition of them.Is there any keyword or method for that. How to do it? Is it possible to do it? In GUI we use adapter classes to achieve it. What for console application?
View Replies View RelatedI have doubts in string declaration. As I know we can declare string in two ways:
1. String a=new String("Hello");
2. String b="Hello";
What is exact difference between them? Another thing is when I check (a==b) it retuns me false, but when I check a.equals(b) it returns me with true. Why So?
I know that I can declare and initialize an member variable inside a class in a single statement but I can't do them on separate sentence. Why?
For example, I am allowed to do the following,
class A{
int a = 5;
// rest of the class
}
But I am not allowed to do this,
class A{
int a;
a = 5; // it doesn't compile even when the variable 'a' is static
// rest of the class
}
Why java don't allow me to do that?
I have an application that uses an object that is declared globally for the class. Within a method that is triggered by a user event, it creates a new object and assigns it to this global object declaration. My question is, when the object is overwritten multiple times by the user selecting the button that calls this method, will the older instances be garbage collected or is there still a reference to them? Is there any downfall to this logic and if so what would be a solution.
View Replies View RelatedI have to implement all the stack methods in java such as push, pop empty, not using the ready methods but have to create them and to execute an exercise but is sth wrong with it
public class Stiva {
/** the problem is here how to declare the stack 1 and stack 2 and kreu(head) gjmax(size)*/
int Gjmax;
int array[] = new int[Gjmax];
int kreu;
private Stiva stiva1;
private Stiva stiva2;
[Code] .....
import java.util.Scanner;
public class days
{ public EnumTest ()
{ this.day = weeks/months/years}
final int daysInMonth = 30; //constants
final int monthsInYear = 12;
final int daysInWeek = 7;
public void convert()
[Code] ....
after compiling it shows invalid method declaration ; return type required.
I am fetching records from result set and displaying on JSP with <c:forEach> tag
<c:forEach var="outer" items='${ProductList}' varStatus="seq1">
<tr>
<td class='center' nowrap><input type="radio" name="view" id = "view" value="Y" ></td>
<td class='left' nowrap><c:out value='${outer.sourceIndex}' /></td>
<td class='left' nowrap><c:out value='${outer.prodNameAbbr}' /></td>
<td class='left' nowrap><c:out value='${outer.productName}' /></td>
<td class='left' nowrap><c:out value='${outer.effectiveDate}' /></td>
<td class='left' nowrap><c:out value='${outer.uuName}' /></td>
</tr>
</c:forEach>
Below is one row with radio button
SourceIndex ProductAbbreviation Product Name Effective Date UseID
ABC PQR Test123 03/12/2014 smj
I have a view button also to select above radio button. When I select that I need all above values to be set in request.
translate this part to jstl and el?
<%
while(i<nrows){
if(i==0){
%>
<tr>
<td ><b>id_article</b></td>
<td ><b><font color="#FF0033">nbr_stock</font></b></td>
<td ><b>critical_nbr</b></td>
<td ><b><font color="#FF0033">date_first_stock</font></b></td>
[code]....
I am looking at JSP page, which has code line as follows
<%@ page language="java" contentType="text/html; charset=UTF-8"%>
<%@ taglib uri="http://jakarta.apache.org/struts/tags-bean" prefix="bean" %>
<%@ taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html" %>
<%@ taglib uri="http://jakarta.apache.org/struts/tags-logic" prefix="logic" %>
This taglib will have to be installed on local environment. How is it referred in jsp ? I dont see any code in jsp, which refers to the location of JSTL. So how does jsp invoke these tags ? Is it through classpath ?If its so , how is classpath set for JSTL ? Is it just as classpath is set for java ?
i am doing a code using JSTL to fire a query. everything come fine except the resule is not sorted as desired. i am putting the code below--
String sort_order=(String)request.getAttribute("sort_order");
request.setAttribute("sort_order",sort_order);
<sql:query var="viewQueryj" sql= "select USER_ID, PERMISSION_ID, USER_NAME from administrator order by ?">
<sql:param value="${sort_order}"/>
</sql:query>
now the resule is always sorted by USER_ID. if i want to sort it using USER_NAME i pass parameter from controller to this page in sort_oredr variable which comes fine but the result doesn't sort by name, only by id. if i hardcode USER_NAME in query then the result is as desired.
I want to use the list element inside my scriptlet. Below is my code which is not working.
<c:forEach var="social" items="${sociallist}">
<%
callToFunction(%>${social}<%);
%>
</c:forEach>
How can i access social var inside scriptlet.
In JSP page: firstly set the setter of a entity in bean and then set it in session,request etc. and gvet values using foreach loop as follow :
<jsp:useBean id="st" class="beans.student">
<jsp:setProperty name="st" property="roll_no"/>
</jsp:useBean>
<%
[Code]....
Here start is the variable whose value will vary after every time i visit this function.So how would i be able to use above query.
P.S. i was using scriplet before and i was able to deal these issues with scriplet easily.
I have the following data in a file called books.xml in my WEB-INF folder:
<?xml version="1.0"?>
<books>
<book>
<name>Padam History</name>
[Code] ....
I'm using the following code in a jsp:
<c:import var="bookInfo" url="/WEB-INF/books.xml" />
I know that it's finding the file because if I delete books.xml from the WEB-INF folder I get a FileNotFound exception.
However, for some reason it doesn't appear to be importing the data into the bookInfo variable.
I noticed this problem because when I try to parse it via:
<x:parse xml="${bookInfo}" var="output"/>
I get org.xml.sax.SAXParseException: Premature end of file.
When I try to display the data in the variable either by:
<c:out value="${bookInfo}" />
...or by means of a scriptlet (which I realize is not a best practice):
<%
String myVariable = (String)pageContext.getAttribute("bookInfo");
System.out.print("bookInfo=" + myVariable);
%>
...I get nothing.
BTW when I do:
<c:import var="data" url="http://www.tutorialspoint.com"/>
<c:out value="${data}"/>
that works fine!
I have a HashMap returned from the server. There are two conditions
1. HashMap returned with only one set of key value pair or
2. HashMap with multiple set of data key value pairs.
Now in UI I have to display either text box or drop down box depending upon the size of map for that I am using length method
Java Code:
<c:choose>
<c:when test="${fn:length(myDto.mayMapInDto) eq 1}">
display text box
</c:when>
<c:otherwise>
display drop box
</c:otherwise>
</c:choose> mh_sh_highlight_all('java');
I can display drop box by looping but not sure how I can get only one element for text box. Tricky is I can't use key value to access since UI don't know what key will be returned.
I have for values in drop down:
<SELECT name = "productCodeDefault" id="productCodeDefault" value="<c:out value ='${ProductDefBean.productCodeDefault}'/>" >
<OPTION value="" ></OPTION>
<OPTION value="a" >A1</OPTION>
<OPTION value="b" >B1</OPTION>
<OPTION value="c" >C1</OPTION>
<OPTION value="d" >D1</OPTION>
</SELECT>
When I am getting value = "a" from ProductDefBean, In the dropdown 'A1' should get selected. This is not happening. What I need to modify?
Note** When I am doing view Source of my JSP, I am getting value='a'
Is there a way we can open a .chm file stored at server through jsp application without downloading the file and saving it to the local machine.
What I googled is : we cannot download .chm files from a web browser and simply click Open. Download the .chm file to your computer first, right-mouse click it in Windows Explorer and select Properties. Then click Unblock.
But I want my users to simply view the file without downloading it.