Develop Reference

How to Insert ArrayList data to the DataBase

Im try to insert data into Database using ArrayList.there is a Erro msg.
That is my Custmer.class method. this is what i got from when i going to pass ArrayList into another class.
incompatible types: ArrayList<String> cannot be converted to ArrayList<Inquiries>
I want to know how to do this using correct Using OOP concept
public void passingMsg(ArrayList<Inquiries> arrlist){
try {
System.out.println("Method "+arrlist);
String sq = "INSERT INTO Inquiries (name,mail,tp,msg)VALUES(?,?,?)";
PreparedStatement pr = con.prepareStatement(sq);
for(int i=0;i<arrlist.size();i++){
pr.setString(1,arrlist.get(i).getName());
pr.setString(2,arrlist.get(i).getMail());
pr.setString(3,arrlist.get(i).getTp());
pr.setString(4,arrlist.get(i).getMsg());
}
pr.executeQuery();//executeBatch();
} catch (SQLException ex) {
}
}
and this is how i get values from user
String name = txtName.getText();
String mail = txtEmail.getText();
String tp = txtTp.getText();
String msg = txtMsg.getText();
ArrayList<String> arrInq = new ArrayList<String>();
arrInq.add(name);
arrInq.add(mail);
arrInq.add(tp);
arrInq.add(msg);
Custmer c =new Custmer();
if( c.passingMsg(arrInq)){
try {
JOptionPane.showMessageDialog(this, "Successs!!");
} catch (Exception e) {
JOptionPane.showMessageDialog(this, "Unsuccesss!!");
e.printStackTrace();
}
}
and this is my Inquiries.class :
public class Inquiries {
private String name;
private String mail;
private String tp;
private String msg;
public Inquiries(String name,String mail,String tp,String msg){
this.name = name;
this.mail = mail;
this.tp = tp;
this.msg = msg;
}
//
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getMail() {
return mail;
}
public void setMail(String mail) {
this.mail = mail;
}
public String getTp() {
return tp;
}
public void setTp(String tp) {
this.tp = tp;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
}
Can Some one please explain whats wrong with this. please ?

Reason For Error
This was simply telling you that your types were incompatible for the operation you were trying to perform. In your passingMsg() method, you have its header as: public void passingMsg(ArrayList<Inquiries> arrlist). However, inside your "how i get values from user" area, which I will now refer to as "2nd Snippet", you have your method call declared as: if( c.passingMsg(arrInq)). This means that you are implying that your parameter being passed, arrInq in this case, is of the type ArrayList<Inquiries>, but it's not. It's being initialized in your 2nd Snippet as: ArrayList<String> arrInq = new ArrayList<String>();
Simple Fix
I take no responsibility for this code; use at your own risk. To fix this, you would want to change that entire 2nd Snippet to something similar to the following:
String name = txtName.getText();
String mail = txtEmail.getText();
String tp = txtTp.getText();
String msg = txtMsg.getText();
ArrayList<Inquiries> arrInq = new ArrayList<Inquiries>();
arrInq.add(new Inquiries(name, mail, tp, msg));
Custmer c = new Custmer();
try {
c.passingMsg(arrInq);
JOptionPane.showMessageDialog(this, "Successs!!");
} catch (Exception e) {
JOptionPane.showMessageDialog(this, "Unsuccesss!!");
e.printStackTrace();
}
You would also want to change the method header to either return a boolean, or fix it up a little bit to actually throw the exception. Such as:
public void passingMsg(ArrayList<Inquiries> arrlist) {
System.out.println("Method " + arrlist);
String sq = "INSERT INTO Inquiries(name,mail,tp,msg) VALUES(?,?,?)";
PreparedStatement pr = con.prepareStatement(sq);
for (Inquiries inquiries : arrlist) {
pr.setString(1, inquiries.getName());
pr.setString(2, inquiries.getMail());
pr.setString(3, inquiries.getTp());
pr.setString(4, inquiries.getMsg());
}
pr.executeQuery();//executeBatch();
}

Let's talk in O-O-P way.
Here Inquiries is your model, model is nothing but simple class that has instance members and public methods to get and set value of model's instance variable.
Generally we put all database related operations code in their respective models.
e.g. I have model "Model" which typically maps to database table say it as "TableModel" ,I would do something like this:
public class Model{
private int id;
private String attr;
//other properties of the model
public int getId(){
return id;
}
public void setId(int id){
this.id=id;
}
//other getters and setters
//here we write methods to performs database operations
public void save(){
//use "this" to get properties of object
//logic to save to this object in database table TableModel as record
}
public void delete(int id){
//logic to delete this object i.e. from database table TableModel
}
public Model get(int id){
//retrieve record from table TableModel with this id
}
//other methods to get data from database.
}
Now question is how I can use this in some another class. Let's say I have list of Model objects and I wish to insert them in to database.I will do it something like this:
public class AnotherClass{
public void someMethod(){
//create list of models objects e.g. get them from user interface
ArrayList<Model> models=new ArrayList<>();
for(int i=0;i<3;i++){
Model model=new Model();
model.setId(i);
model.setAttr("attr"+i);
models.add(model);
}
SomeOtherClass obj=new SomeOtherClass();
obj.insert(models);
}
}
public class SomeOtherClass{
//other code above.....
//my method that inserts each Model object in database
//Note: this is sample method , you should do it in optimized way
// e.g. batch insert
public void insert(ArrayList<Model> models){
for(Model myModel:models){
myModel.save();
}
}
//other code below.....
}

You are using the wrong type parameter for the ArrayList. Instead of ArrayList<String> you need ArrayList<Inquiries>. To fix the problem, you should remove this code ...
ArrayList<String> arrInq = new ArrayList<String>();
arrInq.add(name);
arrInq.add(mail);
arrInq.add(tp);
arrInq.add(msg);
... and replace it with this code:
ArrayList<Inquiries> arrInq = new ArrayList<Inquiries>();
arrInq.add(new Inquiries(name, mail, tp, msg));

How to return a private variable

Ok so I'm trying to get a better understanding of how to return a private variable from a class that I have created. I've only provided a small snippet of my main program to explain my question, so if more information is needed please let me know. My goal is to return a string from the class (working great), but also be able to return the private variables individually as needed (example used below is "flight_number").
public class Flights {
private String dest_city, dest_state, departureDate, departureTime;
private int flight_number;
public Flights(String city, String state, String dDate, String dTime, int flightNumber) {
dest_city = city;
dest_state = state;
departureDate = dDate;
departureTime = dTime;
flight_number = flightNumber;
}
public String toString() {
return "Flight number: " + flight_number + " Destination: " + dest_city + "," + dest_state + " Departing on:" + departureDate + " at" + departureTime + ".";
}
}
public class dummy {
public static void main(String[] args) {
// Uses the constructor to set values
Flights flight1 = new Flights("Houston", "Texas", "12/20/2014", "12:40 pm", 100);
System.out.println(flight1);
System.out.println(flight_number); // Error: `flight_number` cannot be resolved to a variable.
}
}

You need to add a public getter in Flights and call it from main:
public class Flights {
// all the private fields
public int getFlightNumber() {
return this.flight_number;
}
}
In Main:
public static void main(String[] args) {
Flights flight1 = new Flights("Houston", "Texas"); //...
System.out.println(flight1);
System.out.println(flight1.getFlightNumber()); // call the getter
}

You should start with an editor like eclipse and that should help you get started quickly. Getters and Setters is what you need, but start with Eclipse and you should do better.

Java Swing Object[][] getData() confusion

Hi I'm having some trouble getting started with a problem in a Java course learning Swing and starting on JTables and getting data into them. It's going to be hard to explain so I'm just going to post the code I was given, along with the question.
The question is:
The getData() method needs to return an Object[][] containing the data represented by the class.
The first class is MusicAlbum
class MusicAlbum {
private String id;
private String name;
private String genre;
private boolean isCompilation;
private int track_count;
public MusicAlbum(String id, String name, String genre, boolean isCompilation, int track_count) {
this.id = id;
this.name = name;
this.genre = genre;
this.isCompilation = isCompilation;
this.track_count = track_count;
}
public String getId() {
return id;
}
public String getName() {
return name;
}
public String getGenre() {
return genre;
}
public boolean isCompilation() {
return isCompilation;
}
public int getTrackCount() {
return track_count;
}
public boolean equals(Object obj) {
if (obj instanceof MusicAlbum)
return this.id.equalsIgnoreCase(((MusicAlbum)obj).id);
return super.equals(obj);
}
}
The class I have to implement the methods in is MusicDataObject (at the bottom)
import java.util.Random;
import java.util.Scanner;
public class MusicDataObject {
private List<MusicAlbum> albums = new ArrayList<>();
private Random random = new Random(); // for generating IDs
public void addAlbum(MusicAlbum album) throws IllegalArgumentException {
if (searchAlbum(album.getId()) != null)
throw new IllegalArgumentException("Album ID is not new!");
albums.add(album);
}
public MusicAlbum searchAlbum(String id) {
for (MusicAlbum album : albums) {
if (album.getId().equalsIgnoreCase(id)) {
return album;
}
}
return null;
}
public MusicAlbum removeAlbum(String id) {
MusicAlbum album = searchAlbum(id);
albums.remove(album);
return album;
}
public void updateAlbum(MusicAlbum album)
throws IllegalArgumentException {
if (removeAlbum(album.getId()) == null)
throw new IllegalArgumentException("Album ID does not exist!");
addAlbum(album);
}
public String generateID() {
String formatter = "A%0" + (int)Math.ceil(Math.log10(albums.size() * 2) + 1) + "d";
String ID;
do {
ID = String.format(formatter, random.nextInt(albums.size() * 2 + 1));
} while (searchAlbum(ID) != null);
return ID;
}
public void saveData(String fileName) throws IOException {
// make sure that the file exists or try to create it
File fout = new File(fileName);
if (!fout.exists() && !fout.createNewFile())
return;
PrintWriter out = new PrintWriter(fout);
for (MusicAlbum album: albums) {
out.println(serializeAlbum(album));
}
out.close();
}
public String serializeAlbum(MusicAlbum album) {
return String.format(
"%s;%s;%s;%b;%d",
album.getId(),
album.getName(),
album.getGenre(),
album.isCompilation(),
album.getTrackCount());
}
public void loadFile(String fileName) throws FileNotFoundException {
albums = new ArrayList<>();
Scanner in = new Scanner(new File(fileName));
while (in.hasNext()) {
// --- split the next line with the character ";"
String line = in.nextLine();
String[] tokens = line.split(";");
// --- construct a new MusicAlbum using the resulting tokens. NOTE: This isn't very robust.
// If a line doesn't contain enough data or the data is invalid, this will crash
albums.add(new MusicAlbum(
tokens[0],
tokens[1],
tokens[2],
Boolean.parseBoolean(tokens[3]),
Integer.parseInt(tokens[4])
));
}
}
// ----- these methods need to be implemented
public Object[][] getData() {
// TODO
}
public String[] getColumnNames() {
// TODO
}
}
The sample data being used is in a txt file, formatted as so:
A01;Defiance;Soundtrack;true;24
A02;Insomniac;Punk Rock;false;14
A03;A Great Day For The Race;Gypsy Jazz;false;10
A04;Viva La Internet;Ska;false;31
A05;New Surrender;Rock;false;17
So basically it's this getData() method they want me to implement that is giving me grief. I don't fully understand what they want me to do, nor do I fully understand what the Object[][] does.
I hope I have been clear enough, and I will appreciate all help given. Also please try to explain things as best you can and dumb them down as much as possible, I'm new to a lot of this :)
Thanks for your time.

Object[][] is a 2-dimensional array. Each of its element is an Object[], a one-dimensional array.
Your task is to create a 2 dimensional array, having one element (Object[]) for each of your MusicAlbum. An Object[] should hold the properties of a MusicAlbum like id, name, genre, isCompilation and track_count.
You can create an object array like this:
Object[] arr = new Object[] { "some", "values", 23, true };
You can create a 2 dimensional array like this:
Object[][] arr2d = new Object[size][];
And you can iterate over all your MusicAlbums, create an Object[] for each of them containing the properties of that music album, and set it in the arr2d.
You can set/get elements of a 2-dimensional array just like any other arrays:
// Set first element:
arr2d[0] = arr;
// Get first element:
Object[] firstElement = arr2d[0];
The getColumnNames() method should just return a String[] (a String array) containing the column names, the names of the properties.
And it might be obvious but note that the order you return the column names and the order of the property values (in the elements of the Object[]) should be the same.

Update a single variable of a class in an ArrayList of class in java

I have a class Components:
public class Components {
int numberOfNets;
String nameOfComp;
String nameOfCompPart;
int numOfPin;
public components(int i, String compName, String partName, int pin) {
this.numberOfNets = i;
this.nameOfComp = compName;
this.nameOfCompPart = partName;
this.numOfPin = pin;
}
}
Inside another class I created an arraylist of Components class:
List<Components> compList = new ArrayList<Components>();
Later in the code, I am adding the elements in List in this way:
compList.add(new Components(0,compName,partName,0));
See, here numberOfNets and numOfPin variables in Components class are initiated with 0 values. But these values are getting calculated/incremented in a later part of code and hence I need to update the new values of only these two variables in each list element. Now from ArrayList doc I get the idea of updating a list element using its index by set operation. But I am confused how to set/update a particular variable of a class in an ArrayList of a class. I need to update only these two mentioned variables, not all of the four variables in Components class. Is there any way to do that?

You should add getter/setter to your component class so that outer class can update component's members
public class Components {
private int numberOfNets;
private String nameOfComp;
private String nameOfCompPart;
private int numOfPin;
public components(int i, String compName, String partName, int pin) {
setNumberOfNets(i);
setNameOfComp(compName);
setNameOfCompPart(partName);
setNumOfPin(pin);
}
public void setNumberOfNets(int numberOfNets) {
this.numberOfNets = numberOfNets;
}
// Similarly other getter and setters
}
You can now modify any data by using following code because get() will return reference to original object so modifying this object will update in ArrayList
compList.get(0).setNumberOfNets(newNumberOfNets);

Example code.
public class Main {
public static void main(String[] args) {
List<Components> compList = new ArrayList<Components>();
compList.add(new Components(0, "compName", "partName", 0));
System.out.println(compList.get(0).toString());
compList.get(0).numberOfNets = 3;
compList.get(0).numOfPin = 3;
System.out.println(compList.get(0).toString());
}
}
Your class.
public class Components {
int numberOfNets;
String nameOfComp;
String nameOfCompPart;
int numOfPin;
public Components(int i, String compName, String partName, int pin) {
this.numberOfNets = i;
this.nameOfComp = compName;
this.nameOfCompPart = partName;
this.numOfPin = pin;
}
public String toString() {
return this.numberOfNets + " " + nameOfComp + " " + nameOfCompPart
+ " " + numOfPin;
}
}
The output:
0 compName partName 0
3 compName partName 3

How To Pass a JRBeanCollectionDataSource to iReport?

I'm currently trying to use jasper to help me create reports. I have the information and data that I want displayed in this method:
private void writeToFile(final List<ScenarioLoadModel> sceneLoadModel) throws Exception {
final BufferedWriter bw = new BufferedWriter(new FileWriter("/Uma/nft/result.psv"));
for (final ScenarioLoadModel slm : sceneLoadModel) {
bw.write(slm.getScenarioId() + PSP + slm.getScenarioId() + PSP + slm.getScenarioConfig().getName() + PSP + slm.getLoad() + PSP + "" + EOL);
if (!slm.getScenarios().isEmpty()) {
final int tempCount = slm.getScenarios().get(0).getTemplates().size();
final int sceneCount = slm.getScenarios().size();
for (int tempIdx = 0; tempIdx < tempCount; tempIdx++) {
String id = null;
int pass = 0;
int fail = 0;
final Map<String, BigDecimal> metricMap = new HashMap<String, BigDecimal>();
final DefaultStatisticalCategoryDataset dataset = new DefaultStatisticalCategoryDataset();
for (int sceneIdx = 0; sceneIdx < sceneCount; sceneIdx++) {
final Template temp = slm.getScenarios().get(sceneIdx).getTemplates().get(tempIdx);
if (temp.isError()) {
fail++;
} else {
pass++;
}
if (sceneIdx == 0) {
id = temp.getId();
}
final MetricGroupModel mgm = slm.getScenarios().get(sceneIdx).getMetricGroupModel().get(tempIdx);
if (mgm != null) {
for (final MetricModel mm : mgm.getMetricModel()) {
for (final MetricValue mv : mm.getMetricValue()) {
dataset.add(mv.getValue(), new BigDecimal(0.0), mv.getType(), id);
}
}
}
}
final TemplateConfig tc = TemplateManager.getTemplateConfig(id);
bw.write(slm.getScenarioId() + PSP);
bw.write(id + PSP + tc.getName() + PSP + 1 + PSP + pass + "/" + fail);
for (final Object row : dataset.getRowKeys()) {
final Number mean = dataset.getValue((String) row, id);
bw.write(PSP + row + PSP + mean);
}
bw.write(EOL);
}
}
}
bw.close();
}
From my understanding I create Beans and then put them all in a Bean Factory, to create my object that will be ready to be passed to iReport.
How can I put all this information into a Bean? I essentially want the bean to include the scenario/test case and whether or not it passed. (This is for test automation)

I tried to read your code to make a a best guess at what columns you would want, but with no context, I have no clue. All the bean is a pojo, with private fields and public getters and setters.
Assuming there is no grouping and essentially each ScenarioLoadModel will correspond to one row in the report you would end up with a bean like this:
public class ScenariaResults {
private String id;
private String name;
private String load;
private int passCount;
private int failCount;
public ScenariaResults(String id, String name, String load, int passCount,
int failCount) {
super();
this.id = id;
this.name = name;
this.load = load;
this.passCount = passCount;
this.failCount = failCount;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getLoad() {
return load;
}
public void setLoad(String load) {
this.load = load;
}
public int getPassCount() {
return passCount;
}
public void setPassCount(int passCount) {
this.passCount = passCount;
}
public int getFailCount() {
return failCount;
}
public void setFailCount(int failCount) {
this.failCount = failCount;
}
#Override
public String toString() {
return "ScenariaResults [id=" + id + ", name=" + name + ", load="
+ load + ", passCount=" + passCount + ", failCount="
+ failCount + "]";
}
}
So basically in the code you have above you build instances of ScenarioResults and add them to a list. Once you have the list, all you need to do is create a JRDataSource:
List<ScenarioResults> dataBeanList = ...call your method to get the list of results
//create the datasource
JRDataSource dataSource = new JRBeanCollectionDataSource(dataBeanList);
Now when designing the report in iReport it can be a little tricky to get the fields imported automatically. Basically first add your project with the bean to the classpath in iReports (could just point it to the bin folder or jar file`): Tools -> options -> classpath tab. Now follow these steps to add the fields.
Click the following icon:
Select the JavaBean Datasource tab.
Enter the classname of your bean. (ex. ScenarioResults)
Click Read attributes
Highlight the fields you want in the report and click Add Selected Field(s).
Click OK.
Now if you want to test what the report looks like with data, and not just an empty datasource, this is where the Factory comes in. It is only for testing while using iReport. You need to create a class that will essentially create a dummy data set for you. It should look something like:
import java.util.ArrayList;
import java.util.List;
public class ScenarioResultsFactory {
public static List<ScenarioResults> createBeanCollection() {
List<ScenarioResults> list = new ArrayList<ScenarioResults>();
list.add(new ScenarioResults("1", "test", "load", 10, 5));
//add as many as you want
return list;
}
}
Now you need to create a Datasource pointing to it in iReport.
Next to the Datasource dropdown in the toolbar click the icon with the tooltip `Report Datasources.
Click New.
Select JavaBeans set datasource. Click Next.
For name enter ScenarioResultsFactory.
For the Factory class you need to put the classname including package. So if the class is in the com package you should have com.ScenarioResultsFactory here.
For the static method put createBeanCollection if not already there.
Check the Use field description check box. Click Test to make sure it worked.
Click Save.