Null Is Being Shown When List Containing Data From Database Is Displayed Through JSP
Dec 11, 2014
I'am new to java, this question may have been asked earlier but I'm not getting the exact answer.I want to add data from database into at and display it through jsp. But empty or null values is shown i.e no data is being displayed and when I execute the same sql query which is used in code in sql server then required output is displayed. My java code is:
Java Code:
public List < Alarm_Bean > get_Count(String system_Name)
{
if (system_Name.equals("MPS"))
{
try {
con = getConnection();
stmt = con.createStatement();
i am newbie to servlet and m working on a project like online shopping. I have list of data items in my database and i am able to fetch and display the data from database but i want to know that how can i store these data items in ServletContext so that i can use use it frequently in other pages.
I'm new to JSF and I'm facing a problem with displaying German umlauts correctly.
I have built a site that uses an inputText to submit text that will be displayed in a list of paragraphs (as simple html... <li><p>text</p></li> etc.). A managed bean is used as a controller to store data in backend and to retrieve it from backend for display. In backend the data is stored in a list of strings and using annotations this data is written to respectively read from file system on shutdown/startup via serialization. Sometimes when I'm sending German umlauts from my webbrowser they're not displayed correctly, other times however they are which is pretty weird to me.
I've built the project with NetBeans 8 and I made sure that under Properties -> Sources the Encoding is set to UTF-8. In the xhtml page for display the encoding is set as follwed:
<?xml version="1.0" encoding="UTF-8"?> //first line <meta http-equiv="content-type" content="text/html; charset=utf-8"/> //in the head <h:form [...] acceptcharset="UTF-8"> //all forms surrounding the inputText and the paragaraph list
I'm developing on a Ubuntu 14.04 desktop. For deployment I transfer the .war file via ssh to my server which is Ubuntu server (currently not sure which version, might be 12) and there I deploy the .war file on my Glassfish server online.
An example of how the input appears when it's incorrectly displayed: ä
The same letter appears like this when it's correctly displayed: ä
Another example, incorrect: ö
correct: ö
Once the data is input its appearance won't change anymore so I assume the incorrect encoding happens already before the data is stored in backend. I'm not sure yet under which conditions the data is displayed incorrectly.
I am trying to get items to display that would display in a command prompt now into a GUI. I am freaking lost at the moment, probably because I've been staring at this code for over a week now. I have included all the files that are necessary to run the program as an attachment for your own testing purposes. Should I be using a TextField to display the data from the CSV files? How do I get the data to be displayed? How would I get it to be displayed based on the different files Staples (newSTPL.csv), Apple (newAPPL.csv), and Microsoft (newMSFT.csv)?
Java Code:
import javax.swing.*; import java.awt.*; import java.awt.event.*; /** * DataAnalyzer Class * This class instantiates the methods from the ReadFiles Class and Calculations Class.
I'm using BarChart and I've a very strange problem. Is not very simple create a test case to understand where is the problem.
In the first image is displayed a bar with the value of 2 but as you can see the y axis is not correct.
In the second image the value displayed is 4 but the y axis is completely busted.
Important thing: In my real app I change data of the chart every time the user change a combobox value (the period).
First image Second image
This is a test case that simulate what I'm doing in my app with the only difference that data are fetched remotely with an async request in my real app.
Chart.java
public class Chart extends Application implements Initializable { @FXML private BarChart<String, Integer> chart; private ObjectProperty<ObservableList<Series<String, Integer>>> seriesProperty = new SimpleObjectProperty<ObservableList<Series<String, Integer>>>();
[Code] .....
Unfortunately with this simple test case the chart display correctly data.
I have some class called sorted to sort the linked list through the nodes of the list. and other class to test this ability, i made object of the sort class called "list1" and insert the values to the linked list.
If i make other object called "list2" and want to merge those two lists by using method merge in sort class. And wrote code of
list1.merge(list2);
How can the merge method in sort class know the values of list1 that called it as this object is created in other class.
I am currently making a double linked list class in my compsci class. i was absent for a few days and i need to make an add method for the class. when i go to compile test code i made i get a null pointer error on line 36. This is the node class i wrote and the double linked list class i wrote.
node class
public class Node{ // Two references and Data Node prev; Node next; String data; public Node(){ prev = null; next = null;
[Code] ....
This is the class i need working with ( in the doublelinkedlist class)
I have table data I'm trying to read . However one column is populated with the word "null". I guess java does not like dealing with the word null and throws errors.
When I try a block like : if ( rsrow.getString(insCol) = "null") {
I get and error .
If I try :
cmp = rsrow.getString(insCol);If I try:If I try: if (cmp = "null") {
I get an error
If I try to use a replace function like:
System.out.println(cmp.replace("null", "0"));
Just to see if replace works I get and error.
What is the BEST way to replace this string value with something like "0" when I come across it with out jave throwing an error? I want it such that every time I come across the word "null" I can repalce it with "0".
/** * Compute shortest paths in a graph. * * Your constructor should compute the actual shortest paths and maintain all the information needed to reconstruct them. The returnPath() function should use this information to return the appropriate path of edge ID's from the start to the given end. * * Note that the start and end ID's should be mapped to vertices using the graph's get() function. */ class ShortestPaths { Multigraph graph; final int INF = Integer.MAX_VALUE; PriorityQueue<Integer> Q;
[Code] ....
I followed someone else psuedocode very closely but for whatever reason, my edge[] array is just full of null data, which means I can't actually return the shortest path. Why that's happening/how to fix it? Maybe I'm not understanding dijstra's correctly.
I am trying to export data from a jtable to a pdf report but every time i try running the code it gives me this exception:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at GUI.QC_receiving_book.printButtonActionPerformed(QC_receiving_book.java:309) at GUI.QC_receiving_book.access$600(QC_receiving_book.java:26) at GUI.QC_receiving_book$7.actionPerformed(QC_receiving_book.java:165) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
[Code] ....
I tried avoiding the null exception by using the if statement but it didn't work. The row I choose from the table is full meaning there are no empty attributes. and all the data are imported from a mysql database to the table as String so there can't be any casting errors.
This is the part of the source code with the problem and i will also post the printing method. I tried debugging the class and when stepping into the first if statement it opened the jTable.java file and pointed at the getSelectedRow() method and this sentence "variable information not available.source compiled without -g option"
private void printButtonActionPerformed(java.awt.event.ActionEvent evt) { if(samplesTable.getSelectedRow() >= 0){ int row = samplesTable.getSelectedRow(); System.out.println(row); for(int x=0;x<samplesTable.getColumnCount();x++){ String value = samplesTable.getModel().getValueAt(row, x).toString();
If I change the servlet and have "request.getRequestDispatcher("/pages/ViewCompletedWWDocs.jsp").forward(request, response);" un commented, I get exception "java.lang.IllegalStateException: Cannot forward a response that is already committed".
public void add(int d){ listNode l = new listNode (d, null); l.next = first; first= l; } public list Sum2List (list l1, list l2){ //variables int sum;
[Code] .....
But I have a problem in my first listNode where it ll be pointing to null, thus in the sum2List method the program checks the while condition into false and doesn't go through the loop.
I need to implement an editable JComboBox. It should display a list of rivers from a database. However since the number of rivers is very large, the entries must be dynamically filled after the user has typed in three or more letters.
I have tried to solve this using a KeyAdapter. Everythings works. However after the user has typed in three characters, these three characters are selected in the Combobox. Of course when the user continues to type these chars will be replaced. I have so far not found a solution to deselect the characters and place the cursor at the end.
this.fliessgewaesserComboBox = new JComboBox<UisFliessgewaesser>(); this.fliessgewaesserComboBox.setEditable(true); this.add(this.fliessgewaesserComboBox, c); FliessgewaesserSuchenKeyAdapter fliessgewaesserSuchenKeyAdapter = new FliessgewaesserSuchenKeyAdapter(this); this.fliessgewaesserComboBox.getEditor().getEditorComponent().addKeyListener(fliessgewaesserSuchenKeyAdapter);
I am trying to to insert time onto my jFrame (Netbeans) by using textfields. this is the code i've tried to put into the textfield so whenever i run the program it automatically shows the time.
I am still working on my java course and now we have to create a jar file from a previous project (this is a project where a connection to the database is made and data is shown in a frame).
When I follow the instruction in my course material I don't get it to work. I've tried the following:
1. Open eclipse on windows xp 2. Right click on the project folder in eclipse 3. Click on "export" in the menu that appears 4. Choose "runnable jar" 5. click next 6. I insert the following parameters:
- Launch configuration --> I select my main class - export destination --> I select the folder D: - library handling --> Package required libraries into generated jar
7. click Finish
This is what happens when I dbl click the jarfile (wampserver is running):
1. I get an error: "SQL ERROR: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server."
2. I click ok on the message and the following message appears: "SQL Error: null"
3. I click ok on this message and the frame with the fields appears without data from the database.
I can insert data to table by using JSP Scriptlet easily but I have a hard time with servlet.
public class UsertToDatabase() { public boolean inserUser(String name, String email, String pwd) throws SQLException { PreparedStatement pstmt = null; boolean flag = false; System.out.println("start"); openConn(); System.out.println("start_1"); if(conn == null) {
[code]....
I am positive that the above code function fine. The problem is whenever I call UserToDB() class inside the servlet, and I got this error: java.lang.ClassNotFoundException: org.postgresql.
Driver which mean that my conn (connection) is not connected to the database but I have ensure to do so by calling openConn() before start the transaction.
