Develop Reference

How can I dynamically change the number of items in a JComboBox

private void dropDownMenu(JPanel jp1, String prodId){
int len = storeManager.getInv().getStockAmount(prodId);
int[] nums = new int[len];
String[] numPossible = new String[len];
for (int i=0; i<len; i++){
nums[i] = i+1;
}
for (int i=0; i<len; i++){
numPossible[i] = String.valueOf(nums[i]);
}
JComboBox<String> cb = new JComboBox<String>(numPossible);
JButton okButton = new JButton("Add To Cart");
okButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Product p1 = storeManager.getInv().getProd(prodId);
String quan = (String) cb.getSelectedItem();
int quantity = Integer.parseInt(quan);
if (quantity > storeManager.getInv().getStockAmount(prodId)) {
System.out.println("Not Enough Stock.");
} else {
storeManager.getCart().addToCart(p1, quantity);
storeManager.getInv().removeStockAmount(prodId, quantity);
//update the dropdown menu here
}
}
});
jp1.add(cb);
jp1.add(okButton);
}
Essentially what i am looking for is that whenever i select a number from the drop down menu, i want the number of items in the menu to be reduced by the amount that was added to cart. for example if i add 5 to cart then i want the dropdown menu to go from allowing me to choose 10 to 5 only.
Image of GUI

As a thought...Instead of doing all these conversions from integer to string and string to back to integer in order to fill your combo box, why not just have a combo box of Integer? You're dealing initially with integer quantity values anyways:
JComboBox<Integer> cb = new JComboBox<>();
int len = storeManager.getInv().getStockAmount(prodId);
for (int i = 1; i <= len; i++) {
cb.addItem(i);
}
cb.setSelectedIndex(0);
Your action listener might look something like this now:
okButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Product p1 = storeManager.getInv().getProd(prodId);
int quantity = (int) cb.getSelectedItem();
/* This 'if' statement below would be moot if the Combo-Box
is properly updated unless editing is allowed in the combo
which in this case...disable that feature. */
if (quantity > storeManager.getInv().getStockAmount(prodId)) {
System.out.println("Not Enough Stock.");
} else {
storeManager.getCart().addToCart(p1, quantity);
len = storeManager.getInv().removeStockAmount(prodId, quantity);
cb.removeAllItems();
for (int i = 1; i <= len; i++) { cb.addItem(i); }
cb.setSelectedIndex(0);
}
}
});
Possibly better yet would be to utilize the JSpinner component instead of a Combo Box. A drop-down list in this use case always seems a bit obtrusive in my opinion.

how to set combobox value when choosing jtable data

public void setForm(mhs m)
{
String[] jurusan = {"TI","SI"};
JComboBox<String> cjurusan = new JComboBox<String> (jurusan);
String st;
st = ((String)m.getJurusan()).toUpperCase();
for(int i = 0; i < cjurusan.getItemCount(); i++)
{
String jur = ((String) cjurusan.getItemAt(i)).toUpperCase();
if(jur.equals("SI"))
{
cjurusan.setSelectedIndex(1);
}
else
{
cjurusan.setSelectedIndex(0);
}
}
tnim.setText(m.getNim());
tnama.setText(m.getNama());
cjurusan.setBounds(110,70,90,20);
add(cjurusan);
}
}
I want to set jcombobox's value according the data record in jtable, till now, I just get the data value at the first time, for second time the jcombobox's value is the same with last. please help. many thanks.
This is my sample image program : screenshoot

How can I create a program that stores a numerous amount of names/numbers in an array by clicking a button without the method resetting my counter?

public void actionPerformed(ActionEvent e)
{
int clicked = 0;
if(arg == "Enter")
{
clicked++;
}
if (clicked == 0)
{
names[0] = nameField.getText();
numbers[0] = numberField.getText();
}
if( clicked == 1)
{
names[1] = nameField.getText();
numbers[1] = numberField.getText();
}
if(arg == "Print")
{
String name = nameField.getText();
String number = numberField.getText();
JOptionPane.showMessageDialog(null,names[0] + numbers[0] + names[1] + numbers[1] + numbers[2] + names[2],"Info",JOptionPane.INFORMATION_MESSAGE);
}
My program must take multiple names and numbers and be able to enter them into an array. After all of the data is entered, it must be able to be printed. I am having trouble under the Enter method because it continues to reset everytime instead of remaining constant. It only allows me to print the last typed name/number instead of saving all of the content. I am unsure of how to fix this and would be grateful for any suggestions at this point.

You could start by moving int clicked out of this function.
Right now your actionPerformed function each time its called reset your clicked to 0 since you are setting it to 0 at the beggining of it.
public void actionPerformed(ActionEvent e)
{
int clicked = 0; //HERE is your problem
if(arg == "Enter");
...
Making it a variable of class instead of function should help.
EDIT:
You can do something like this:
int clicked = 0
public void actionPerformed(ActionEvent e)
{
if(arg == "Enter"){
names[clicked] = nameField.getText();
numbers[clicked] = numberField.getText();
clicked++;
}
As it was mentioned you could also use List, since it would save problems if you don't know how big of an array u need.
List<String> names = new ArrayList<String>();
List<String> numbers = new ArrayList<String>();
And in use
if(arg == "Enter"){
names.add(nameField.getText());
numbers.add(numberField.getText());
}

Instead of an array, you could use an ArrayList, it will allow you to add elements without having to supply an index.
Without givening away too much, like this:
ArrayList<String> names = new ArrayList<String>();
...
names.add("Johnny"); // Adds to the end of the list
names.add("Frank");
That way you don't need to keep the 'clicked' count.
You can use .get(i) to get the element at index i. Or just loop over the entire list using a for each loop:
for(String name : names) { // i.e. for each 'name' in 'names'
System.out.println(name);
// Or do something else with 'name'
}

if else -if unexpected Message

I have a swing application that involves a Container, a JButton, a JPanel, a JTextArea and an array. The array of String objects and contains 5 elements.
I want to return all elements in the array by a method and compare each of them with the element entered by end user in the text area, after pressing a JButton.
If they are same a JOptionPane message displaying the matched element should appear. If they are different a JoptionPane should show a message saying Number Entered is not found in myArray else, a message saying please Enter something" should appear
The problem I face is that when the end user enters a valid number a JOptionPane message saying: Number Entered is not found in myArray appear many times, e.g. when entering 4, a JoptionPane message saying
Number Entered is not found in myArray appear 3 times.
How do I prevent this message if the entered element is correct?
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class Array_Search extends JFrame {
String myString[] = { "1", "2", "3", "4", "5" };
public String[] get_Element() {
String str[] = new String[myString.length];
str = myString;
return str;
}
public Array_Search() {
Container pane = getContentPane();
JPanel panel = new JPanel();
final JTextField txt = new JTextField(
" ");
JButton b = new JButton("Click Me ");
panel.add(b);
panel.add(txt);
pane.add(panel);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
String[] str = get_Element();
String s2 = txt.getText().trim();
if (s2 != null && s2.length() > 0)
for (int i = 0; i < str.length; i++) {
if (s2.equals(str[i].trim())) {
JOptionPane option = new JOptionPane();
option.showInputDialog("" + str[i]);
} else {
JOptionPane option = new JOptionPane();
option.showInputDialog("Number Entered is not found in myArray");
}
}
else {
JOptionPane o = new JOptionPane();
o.showInputDialog("please Enter something");
}
}
});
}
public static void main(String[] args) {
Array_Search myArray = new Array_Search();
myArray.setSize(500, 500);
myArray.setVisible(true);
}
}

Your code shows message every time when non-matching element is found.
Instead, you need to look through all of the elements and display Not found message after that.
Something like this should work:
...
if (s2 != null && s2.length() > 0) {
boolean isFound = false;
for (int i = 0; i < str.length; i++) {
if (s2.equals(str[i].trim())) {
JOptionPane option = new JOptionPane();
option.showInputDialog("" + str[i]);
isFound = true;
break;
}
}
if(!isFound) {
JOptionPane option = new JOptionPane();
option.showInputDialog("Number Entered is not found in myArray");
}
} else
...

You return an empty Array in your get_Element method.
Can be fixed like that:
public void actionPerformed(ActionEvent ae) {
String [] str = get_Element(); // replace this
String [] str = myString; // with this
or change get_Element to:
public String[] get_Element() {
return myString;
}
Note: by Java code conventions use camel case for method names. getElement instead of get_Element.

Access already running objects - Java

import java.awt.*;
import javax.swing.*;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.TableColumn;
public class vasilisTable extends JFrame {
Object[] split_data_l;
Object[][] split_data;
Object [][] split_data_clone;
Object [][] split_data_reverse;
Object [][] split_data_reverse_num;
String[] temp;
private JTable table;
private JPanel bottom_panel;
private JLabel average;
private JLabel max_dr;
public vasilisTable(String name, String data, int choice)
{
super(name);
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); //the DISPOSE_ON_CLOSE means that when we press the x button is will close only the table window and not the whole programm
//this.getAccessibleContext().setAccessibleName(name);
//System.out.println(this.getAccessibleContext().getAccessibleName());
setSize(800,600);
String[] columnNames = {"Date", "Open","High","Low","Close",
"Volume", "Adjusted" };//defines the column names
//------ Start of making the arrays that will be used as data for the table creation
split_data_l = data.split( "\n" );
int lngth = split_data_l.length;
split_data = new Object[lngth-1][7];
split_data_clone = new Object[lngth-1][7];
split_data_reverse= new Object[lngth-1][7];
split_data_reverse_num= new Object[lngth-1][7];
double sum = 0;
for(int k=1; k<split_data_l.length; k++) //initializing the three arrays with the data we got from the URLReader
{
temp = split_data_l[k].toString().split(",");
for (int l=0; l<temp.length; l++)
{
split_data[k-1][l] = temp[l];
split_data_clone[k-1][l] = temp[l];
split_data_reverse[k-1][l] = temp[l];
split_data_reverse_num[k-1][l] = temp[l];
}
}
for(int k=split_data_l.length-2; k>=1; k--) // making of the clone array that contains all the last column with colours
{
Double temp = Double.parseDouble(split_data[k][6].toString());
Double temp1 = Double.parseDouble(split_data[k-1][6].toString());
double check =temp-temp1;
if (check>0)
{
String color_temp = "<html><span style = 'color:red'>" + split_data_clone[k-1][6] +"</span></html>" ;
split_data_clone[k-1][6] = color_temp;
}
else
{
String color_temp = "<html><span style = 'color:green'>" +split_data_clone[k-1][6]+"</span></html>" ;
split_data_clone[k-1][6] = color_temp;
}
}
int l = split_data_clone.length;
int m = l-1;
for (int i=0; i<l; i++) //making of the reversed array
{
for (int j = 0; j<=6; j++)
{
split_data_reverse[i][j]=split_data_clone[m][j];
}
m--;
}
m = l-1;
for (int i=0; i<l; i++) //making of the reversed array
{
for (int j = 0; j<=6; j++)
{
split_data_reverse_num[i][j]=split_data[m][j];
}
m--;
}
//------ End of making the arrays that will be used as data for the table creation
//------ Start of calculating the average
for (int i=0; i<lngth-1; i++)
{
Double temp = Double.parseDouble(split_data[i][6].toString());
sum = sum+temp;
//System.out.println("turn "+i+" = "+split_data[i][6]);
}
float avg = (float) (sum/(lngth-1));
avg = Round((float) avg,2);
String avg_str;
avg_str = "<html>Average: <b>"+avg+"</b></html>";
//"<html><b>Average: </b></html>"
//------ End of calculating the average
//------ Start of Calculating the Maximal Drawdown
double high=0;
double low=100000000;
double drawdown=0;
double max_drawdown=0;
int last_high=0;
int last_low=0;
for (int i=0; i<lngth-1; i++)
{
Double temp = Double.parseDouble(split_data_reverse_num[i][6].toString());
//Double temp1 = Double.parseDouble(split_data[i+1][6].toString());
if (temp>high)
{
high = temp;
last_high = i;
//System.out.println("max high = "+temp);
}
else
{
low = temp;
last_low = i;
//System.out.println("max low = "+temp);
}
if (last_low>last_high)
{
drawdown = high-low;
//System.out.println("drawdown = "+drawdown);
}
if (drawdown>max_drawdown)
{
max_drawdown = drawdown;
}
}
//System.out.println("max dr = "+max_drawdown);
String max_dr_str = "<html>Maximal Drawdown: <b>"+max_drawdown+"</b></html>";
//------ End of Calculating the Maximal Drawdown
average = new JLabel(avg_str);
max_dr = new JLabel(max_dr_str);
bottom_panel = new JPanel();
String space = " ";
JLabel space_lbl = new JLabel(space);
bottom_panel.add(average);
bottom_panel.add(space_lbl);
bottom_panel.add(max_dr);
//-------- Start of table creation ---------
if(choice==1)
{
table = new JTable(split_data_clone, columnNames);//creates an instance of the table with chronological order
}else
{
table = new JTable(split_data_reverse, columnNames);//creates an instance of the table with reverse chronological order
}
TableColumn column = null;
for (int i = 0; i < 7; i++) {
column = table.getColumnModel().getColumn(i);
if (i == 0) {
column.setPreferredWidth(100); //third column is bigger
} else if (i == 5) {
column.setPreferredWidth(85); //third column is bigger
}
else if (i == 6) {
column.setPreferredWidth(70); //third column is bigger
}
else {
column.setPreferredWidth(50);
}
}
table.setShowGrid(true);
table.setGridColor(Color.black);
//-------- End of table creation ---------
JPanel table_panel = new JPanel (new BorderLayout());
JScrollPane table_container = new JScrollPane(table); // create a container where we will put the table
//table.setFillsViewportHeight(true); // if the information are not enough it still fill the rest of the screen with cells
table_panel.add(table_container, BorderLayout.CENTER);
table_panel.add(bottom_panel, BorderLayout.SOUTH);
//table_panel.add();
setContentPane (table_panel);
pack(); // here i pack the final result to decrease its dimensions
}
public float Round(float Rval, int Rpl) // this functions rounds the number to 2 decimal points
{
float p = (float)Math.pow(10,Rpl);
Rval = Rval * p;
float tmp = Math.round(Rval);
return (float)tmp/p;
}
}
I am making an application which creates various instances of a class. These instances are actually some windows. After having create multiple of these windows, how can I access one of them and bring it in front? I know the .tofront() method, but how can I specify the window that I want to bring in front?
Above is the code that creates every window. My main problem is that after I have create e.g 5 windows, how can I access one of them?
ps
code that creates each window:
if (sData != null) {
//System.out.println("Success, waiting response");
vasilisTable ftable = new vasilisTable(name, sData, choice);
hashMap.put(name, ftable);
ftable.setVisible(true);
//choice=2;
}

My main problem is that after I have create e.g 5 windows, how can I access one of them?
You have to keep a reference to the relevant objects in variables or an array or a collection or something. The "bring it to the front" function needs to:
figure out what domain object needs to be brought to the front,
lookup its corresponding JFrame, and
call toFront() on it.
Java provides no built-in mechanisms for finding previously created instances of objects.

When you create your various instances of the above JFrame, you can keep track of the created instances, may be store them within a HashMap, then you can pick the right JFrame instance basing on its designated name and bring it to the front. Have a look at the below code for more illustration:
HashMap<String, VasilisTable> hashMap = new HashMap<String, VasilisTable>();
JFrame firstWindow = new VasilisTable("firstWindow",data, choice);
hashMap.put("firstWindow", firstWindow);
JFrame secondWindow = new VasilisTable("secondWindow",data, choice);
hashMap.put("secondWindow", secondWindow);
JFrame thirdWindow = new VasilisTable("thirdWindow",data, choice);
hashMap.put("thirdWindow", thirdWindow);
// To bring a certain window to the front
JFrame window = hashMap.get("firstWindow");
window.setVisible(true);
window.toFront();

Are these JFrame or JWindow objects? If they are you can call -
jframe.setVisible(true);
jframe.toFront();
This is something interesting I found at the API doc.
Places this Window at the top of the stacking order and shows it in
front of any other Windows in this VM. No action will take place if
this Window is not visible. Some platforms do not allow Windows which
own other Windows to appear on top of those owned Windows. Some
platforms may not permit this VM to place its Windows above windows of
native applications, or Windows of other VMs. This permission may
depend on whether a Window in this VM is already focused. Every
attempt will be made to move this Window as high as possible in the
stacking order; however, developers should not assume that this method
will move this Window above all other windows in every situation.
I would recommend you to check out these answers as well.
Java Swing: JWindow appears behind all other process windows, and will not disappear
Java: How can I bring a JFrame to the front?