I am working on a project, using cassandra 1.2, hadoop 1.2
I have created my normal cassandra mapper and reducer, but I want to create my own Input format class, which will read the records from cassandra, and I'll get the desired column's value, by splitting that value using splitting and indexing ,
so, I planned to create custom Format class. but I'm confused and not able to know, how would I make it? What classes are to be extend and implement, and how I will able to fetch the row key, column name, columns value etc.
I have my Mapperclass as follow:
public class MyMapper extends
Mapper<ByteBuffer, SortedMap<ByteBuffer, IColumn>, Text, Text> {
private Text word = new Text();
MyJDBC db = new MyJDBC();
public void map(ByteBuffer key, SortedMap<ByteBuffer, IColumn> columns,
Context context) throws IOException, InterruptedException {
long std_id = Long.parseLong(ByteBufferUtil.string(key));
long newSavePoint = 0;
if (columns.values().isEmpty()) {
System.out.println("EMPTY ITERATOR");
sb.append("column_N/A" + ":" + "N/A" + " , ");
} else {
for (IColumn cell : columns.values()) {
name = ByteBufferUtil.string(cell.name());
String value = null;
if (name.contains("int")) {
value = String.valueOf(ByteBufferUtil.toInt(cell.value()));
} else {
value = ByteBufferUtil.string(cell.value());
}
String[] data = value.toString().split(",");
// if (data[0].equalsIgnoreCase("login")) {
Long[] dif = getDateDiffe(d1, d2);
// logics i want to perform inside my custominput class , rather here, i just want a simple mapper class
if (condition1 && condition2) {
myhits++;
sb.append(":\t " + data[0] + " " + data[2] + " "+ data[1] /* + " " + data[3] */+ "\n");
newSavePoint = d2;
}
}
sb.append("~" + like + "~" + newSavePoint + "~");
word.set(sb.toString().replace("\t", ""));
}
db.setInterval(Long.parseLong(ByteBufferUtil.string(key)), newSavePoint);
db.setHits(Long.parseLong(ByteBufferUtil.string(key)), like + "");
context.write(new Text(ByteBufferUtil.string(key)), word);
}
I want to decrease my Mapper Class logics, and want to perform same calculations on my custom input class.
Please help, i wish for the positive r4esponse from stackies...
You can do the intended task by moving the Mapper logic to your custom input class (as you have indicated already)
I found this nice post which explains a similar problem statement as you have. I think it might solve your problem.
Related
I am working on a Java class that contains a ton of numeric fields. Most of them would begin with something like 'CMTH' or 'FYTD'. Is it possible to initialize all fields of the same type that begin or end with a certain value. For example I have the following fields:
CMthRepCaseACR CMthRepUnitACR CMthRecCaseACR CMthRecUnitACR CMthHecCaseACR CMthHecUnitACR FYTDHecCaseACR FYTDHecUnitACR CMthBBKCaseACR CMthBBKUnitACR CMthPIHCaseACR .
I am trying to figure if it is possible to initialize all fields to zero that end with an 'ACR' or begin with an 'Cmth"
I know I can do something like cmtha = cmthb = cmthc = 0 but I was wondering there was a command where you can some kind of mask to initialize
Thanks
Assuming that you cannot change that said Java class (and e.g. use a collection or map to store the values) your best bet is probably reflection (see also: Trail: The Reflection API). Reflection gives you access to all fields of the class and you can then implement whatever matching you'd like.
Here's a short demo to get you started, minus error handling, sanity checks and adaptions to your actual class:
import java.util.stream.Stream;
public class Demo {
private static class DemoClass {
private int repCaseACR = 1;
private int CMthRepUnit = 2;
private int foo = 3;
private int bar = 4;
#Override
public String toString() {
return "DemoClass [repCaseACR=" + repCaseACR + ", CMthRepUnit=" + CMthRepUnit + ", foo=" + foo + ", bar="
+ bar + "]";
}
}
public static void main(String[] args) {
DemoClass demoClass = new DemoClass();
System.out.println("before: " + demoClass);
resetFields(demoClass, "CMth", null);
System.out.println("after prefix reset: " + demoClass);
resetFields(demoClass, null, "ACR");
System.out.println("after suffix reset: " + demoClass);
}
private static void resetFields(DemoClass instance, String prefix, String suffix) {
Stream.of(instance.getClass().getDeclaredFields())
.filter(field ->
(prefix != null && field.getName().startsWith(prefix))
|| (suffix != null && field.getName().endsWith(suffix)))
.forEach(field -> {
field.setAccessible(true);
try {
field.set(instance, 0);
} catch (IllegalArgumentException | IllegalAccessException e) {
// TODO handle me
}
});
}
}
Output:
before: DemoClass [repCaseACR=1, CMthRepUnit=2, foo=3, bar=4]
after prefix reset: DemoClass [repCaseACR=1, CMthRepUnit=0, foo=3, bar=4]
after suffix reset: DemoClass [repCaseACR=0, CMthRepUnit=0, foo=3, bar=4]
Note: Both links are seriously dated but the core functionality of reflection is still the same.
I have a List having values which I want to send through mail. But in mail I AM only getting the last value, rather then all values. Below is my code
private String sName[];
private String sID[];
method abc()
{
some code.....
final int numberOfStudentsAdded = recentlyJoinedStudents.size();
sName= new String[numberOfStudentsAdded];
sID=new String[numberOfStudentsAdded]
for(int i=0;i<numberOfStudentsAdded;i++)
{
for(final Student s :recentlyJoinedStudents )
{
sName[i]=s.getName();
sID[i]=s.getId();
}
message.setText(
"<table><tr><td><h6>Student Name</h6></td><td><h6>Student ID</h6></td></tr><tr><td>"
+ sName[i] + "</td><td>" + sID[i] + "</td><td></tr></table>", true);
}}
Problem with above code is suppose I have 3 students in my list. But it gives record of last student. I want required output as
Student Name Student ID
abc 1
xyz 2
pqr 3
but I am getting output as
Student Name Student ID
pqr 3
How can I achieve that. What is wrong in my code.
You are overwritten all the time with the text message property with message.setText(""). And I do not understand the two loops. Try this piece of code instead :)
String text = "<table><tr><td><h6>Student Name</h6></td><td><h6>Student ID</h6></td></tr>";
for(int i=0;i<recentlyJoinedStudents.size();i++) {
text += "<tr><td>" + recentlyJoinedStudents.get(i).getName() + "</td><td>"
+ recentlyJoinedStudents.get(i).getId() + "</td><td></tr>";
}
text += "</table>";
System.out.print(text);
As #a-sir said, you are overriding it everytime by setting value as
Change your code to following
private String sName[];
private String sID[];
method abc()
{
some code.....
final int numberOfStudentsAdded = recentlyJoinedStudents.size();
sName= new String[numberOfStudentsAdded];
sID=new String[numberOfStudentsAdded];
StringBuilder dataTable = new StringBuilder("<table><tr><td><h6>Student Name</h6></td><td><h6>Student ID</h6></td></tr>");
for(int i=0;i<numberOfStudentsAdded;i++)
{
for(final Student s :recentlyJoinedStudents )
{
sName[i]=s.getName();
sID[i]=s.getId();
}
dataTable.append("<tr><td>"+ sName[i] + "</td><td>" + sID[i] + "</td><td></tr>");
}
dataTable.append("</table>");
message.setText(dataTable.toString(), true);
}
I've created a database using Berkley DB that stores N records where a record is a key/value pair. I originally populated it with only 20 records. With 20 records I managed to do a Key Search, and a Data Search (where I search through the database record by record for a data value that matches the string data inputted by the user).
public String dataSearch (String dataInput) {
String foundKey = null;
String foundData = null;
Cursor cursor = null;
try {
cursor = myDb.openCursor(null, null);
DatabaseEntry theKey = new DatabaseEntry();
DatabaseEntry theData = new DatabaseEntry();
while (cursor.getNext(theKey, theData, LockMode.DEFAULT) == OperationStatus.SUCCESS) {
foundKey = new String(theKey.getData(), "UTF-8");
foundData = new String(theData.getData(), "UTF-8");
// this is to see each key - data - inputdata as I was having an issue
System.out.println("KEY: " + foundKey +
"\nDATA: " + foundData +
"\nINPUT_DATA: " + dataInput + "\n\n");
if (foundData.equals(dataInput)) {
System.out.println("-----------------------------------\n\n");
System.out.println("Found record: " + foundKey +
"\nwith data: " + foundData);
System.out.println("\n\n-----------------------------------");
}
}
/* I then close the cursor and catch exceptions and such */
this works fine when I have less than (or equal to) 20 records... but when I use a bigger number I seem to have some funny behaviour. I set the number of records to 1000... the last key/data values to be inserted into the database are:
KEY: zghxnbujnsztazmnrmrlhjsjfeexohxqotjafliiktlptsquncuejcrebaohblfsqazznheurdqbqbxjmyqr
DATA: jzpqaymwwnoqzvxykowdhxvfbuhrsfojivugrmvmybbvurxmdvmrclalzfscmeknyzkqmrcflzdooyupwznvxikermrbicapynwspbbritjyeltywmmslpeuzsmh
I had it print out the last values to be inserted into the database then did a key search on the above key to ensure that the data above was infact the data associated with that key in the database. However, when I do a data search on the data listed above I get no found matching record (whereas the same process found a record when there was 20 records). I looked into it a bit more and got each my data search to print each key/data pair that it returned and found the following result:
KEY: zghxnbujnsztazmnrmrlhjsjfeexohxqotjafliiktlptsquncuejcrebaohblfsqazznheurdqbqbxjmyqrpzlyvnmdlvgyvzhbceeftcqssbeckxkuepxyphsgdzd
DATA: jzpqaymwwnoqzvxykowdhxvfbuhrsfojivugrmvmybbvurxmdvmrclalzfscmeknyzkqmrcflzdooyupwznvxikermrbicapynwspbbritjyeltywmmslpeuzsmhozy
INPUT DATA: jzpqaymwwnoqzvxykowdhxvfbuhrsfojivugrmvmybbvurxmdvmrclalzfscmeknyzkqmrcflzdooyupwznvxikermrbicapynwspbbritjyeltywmmslpeuzsmh
as you can see it seems to have randomly appended some extra bytes to the data value. however if I do a key search these extra bytes don't show up. So I think the problem is in the dataSearch function. The same results occur if I use b+tree or hash.
Any Ideas?
Thanks
After a long time looking at this I realized my error was that I was not reinitializing the theKey & theData variables.
the fix is in the while loop
while (cursor.getNext(theKey, theData, LockMode.DEFAULT) == OperationStatus.SUCCESS) {
foundKey = new String(theKey.getData(), "UTF-8");
foundData = new String(theData.getData(), "UTF-8");
// this is to see each key - data - inputdata as I was having an issue
System.out.println("KEY: " + foundKey +
"\nDATA: " + foundData +
"\nINPUT_DATA: " + dataInput + "\n\n");
if (foundData.equals(dataInput)) {
System.out.println("-----------------------------------\n\n");
System.out.println("Found record: " + foundKey +
"\nwith data: " + foundData);
System.out.println("\n\n-----------------------------------");
}
// THIS IS THE FIX
theKey = new DatabaseEntry();
theData = new DatabaseEntry();
// ----------------------------
}
I have a project as follows: Several photos are taken from a mobile, the photos are saved in a web system, which in turn displays the photos on google earth that is inside it. I've read many articles but all of them were using fetchKml, one good article that i've read was using php, but using fetchKml. I dont know if its possible using parseKml instead. Anyway, I'm not sure how to do this with the kml, so it looks tike this:
My Class KMLGenerator()
public static String getKMLFromObra (List<Obra> obraFotos) {
StringBuffer sb = new StringBuffer();
sb.append("<?xml version='1.0' encoding='UTF-8'?>");
sb.append("<kml xmlns='http://www.opengis.net/kml/2.2' " +
"xmlns:gx='http://www.google.com/kml/ext/2.2' " +
"xmlns:kml='http://www.opengis.net/kml/2.2' " +
"xmlns:atom='http://www.w3.org/2005/Atom'> ");
if (obraFotos != null && obraFotos.size() > 0) {
for (Obra o : obraFotos) {
for (Local local : o.getLocais()) {
sb.append("<Document>");
sb.append("<name>" + local.getName() + "</name>");
sb.append("<Style id='defaultStyles'>");
sb.append("<IconStyle>");
sb.append("<scale>1.1</scale>");
sb.append("<Icon>");
sb.append("<href>" + "http://localhost:8080/ConstruMobilFoto/lib/img/fotoIcon.png" + "</href>");
sb.append("</Icon>");
sb.append("</IconStyle>");
sb.append("</Style>");
sb.append("<Placemark>");
sb.append("<name>" + "Foto" + "</name>");
sb.append("<styleUrl>" + "#defaultStyles"+ "</styleUrl>");
sb.append("<altitudeMode>" + "relativeToGround" + "</altitudeMode>");
sb.append("<Point>");
sb.append("<altitudeMode>relativeToGround</altitudeMode>");
sb.append("<coordinates>" + local.getLongitude() + "," + local.getLatitude() + "," + 50</coordinates>");
sb.append("</Point>");
sb.append("<Link>");
sb.append("<href>" + local.getFotos() + "</href>");
sb.append("</Link>");
sb.append("</Placemark>");
sb.append("</Document>");
sb.append("</kml>");
return sb.toString();
}
}
}
return null;
}
I have a dwr function in my jsp that invokes this method, got its String results and make the parse like this:
Class PainelEarth()
#SuppressWarnings("static-access")
public String geraFotosObra (int idObra) throws Exception {
try {
List<Obra> obraFotos = obraBusiness.getObraLatLong(new Obra(idObra));
return new KMLGenerator().getKMLFromObra(obraFotos);
} catch (Exception e) {
log.error(e.getLocalizedMessage(), e);
return null;
}
}
and in my jsp page
function initCB(instance) {
// other codes
showPics(ge);
}
function showPics(ge) {
PainelEarthAjax.geraFotosObra({
callback : function(kmlString) {
var kmlObject = ge.parseKml(kmlString);
ge.getFeatures().appendChild(kmlObject);
}
});
return null;
}
Any help will be welcome!!
In your code if you look at the signature of the method geraFotosObra you can see it takes a single int parameter idObra.
public String geraFotosObra (int idObra) throws Exception { ...
Yet when you call the method in your jsp you are passing an an object literal containing a callback function.
PainelEarthAjax.geraFotosObra({
callback : function(kmlString) { ...
As it is I don't see how the kml is generated, unless perhaps geraFotosObra is an overloaded method? Also even if it was generated, as is, I don't see how the callback function that you pass in place of an id is ever called - why for example would kmlString be the result of the call to geraFotosObra?
// How is this called, what sets kmlString!?
callback : function(kmlString) {
var kmlObject = ge.parseKml(kmlString);
ge.getFeatures().appendChild(kmlObject);
}
All in all the code you posted is a wee bit confusing, so sorry if I have missed something...I think you have possibly copy and pasted some code from a fetchKml example and the asynchronous callbacks used with that method have confused you slightly.
Anyhow, based on what you have posted, you should be passing an int id to the geraFotosObra method, getting the string result and then parsing it in the plug-in.
Something like the following makes sense. Replace the showPics function with the following.
function showPics(ge) {
var kmlString = PainelEarthAjax.geraFotosObra(1); // or something?
var kmlObject = ge.parseKml(kmlString);
ge.getFeatures().appendChild(kmlObject);
}
I need help on how to scroll back to the next record on the resultset returned by java. I'm using mysql database.
Here is the code inside the formshow event. Where I load the first resultset that is being returned:
if (rs.next()) {
jLabel5.setText(rs.getString("Question"));
jRadioButton1.setText("A. " + rs.getString("A"));
jRadioButton2.setText("B. " + rs.getString("B"));
jRadioButton3.setText("C. " + rs.getString("C"));
jRadioButton4.setText("D. " + rs.getString("D"));
}
And here's the button which is supposed to be used to scroll forward through the database.
I need to execute rs.beforeFirst because the things that are displayed on the jFrame doesn't match with the variable that I'm trying to validate:
try {
rs.beforeFirst();
if (rs.next()) {
jLabel5.setText(rs.getString("Question"));
jRadioButton1.setText("A. " + rs.getString("A"));
jRadioButton2.setText("B. " + rs.getString("B"));
jRadioButton3.setText("C. " + rs.getString("C"));
jRadioButton4.setText("D. " + rs.getString("D"));
if (jRadioButton1.isSelected()) {
rval = jRadioButton1.getText().charAt(0);
if (String.valueOf(rval).equalsIgnoreCase(rs.getString("Answer"))) {
JOptionPane.showMessageDialog(null, "Correct! Your answer is " + rval + " answer is: " + rs.getString("Answer"));
} else {
JOptionPane.showMessageDialog(null, "Wrong! your answer is " + rval + " answer is: " + rs.getString("Answer"));
}
}
}
}catch (Exception e) {
e.printStackTrace();
}
My question is how do I continue on scrolling through the database. Because the resultset doesn't progress when I use the rs.beforeFirst() before the rs.next()
I also tried doing:
while(rs.next()){...}
It worked but it didn't let me choose what radioButton I want. And it continued to execute until the end of the result set even without manually clicking on the button(for scrolling) multiple times. Please help me figure out what's the solution to this. If you need more details just ask. Thanks.
You shouldn't be mingling database access logic with presentation logic. That only leads to tight coupled code where the both concerns only collides with each other. The database job needs to be done as soon as possible.
You need to separate the concerns.
First create a class which represents a single row of the database.
public class Question {
private String text;
private String answer;
private String optionA;
private String optionB;
private String optionC;
private String optionD;
// Add/generate c'tors/getters/setters/equals/hashcode and other boilerplate.
}
(a bit decent IDE like Eclipse can autogenerate them)
Then create a class which does the following JDBC job:
public List<Question> list() throws SQLException {
List<Question> questions = new ArrayList<Question>();
// ...
try {
// ...
while (resultSet.next()) {
Question question = new Question();
question.setText(resultSet.getString("Question"));
question.setAnswer(resultSet.getString("Answer"));
question.setOptionA(resultSet.getString("A"));
question.setOptionB(resultSet.getString("B"));
question.setOptionC(resultSet.getString("C"));
question.setOptionD(resultSet.getString("D"));
questions.add(question);
}
} finally {
// ...
}
return questions;
}
Finally just work with List<Question> the straightforward way.
List<Question> questions = questionDAO.list();
int size = questions.size();
JOptionPane.showMessageDialog(null, "There are " + size + " questions!");
for (Question question : questions) {
jLabel5.setText(question.getText());
jRadioButton1.setText("A. " + question.getOptionA());
jRadioButton2.setText("B. " + question.getOptionB());
jRadioButton3.setText("C. " + question.getOptionC());
jRadioButton4.setText("D. " + question.getOptionD());
// ...
}
No need to massage the resultset forth and back.