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How Can I Sort JTable With A Button?

Example:
I made a table, and I want a search box for each column. I hid the column titles with this code:
table.setTableHeader(null);
And put a textField and Button to each top of columns. Now I can search for each different column, but I can't sort the items.
I want to sort the column items when I click the top button. I tried some thing but it is so complex for a beginner as me.
Is there any way to do it? Or all the thing i tried useless and there is much easy way to do it? I hope explained it right.
Note :
I have found this code.I dont even know if it does what i need. I did try it but getting error.
/** Default sort behaviour, plus every third click removes the sort. */
private final class CustomSorter extends MouseAdapter {
#Override public void mouseClicked(MouseEvent aEvent) {
int columnIdx = fTable.getColumnModel().getColumnIndexAtX(aEvent.getX());
//build a list of sort keys for this column, and pass it to the sorter
//you can build the list to fit your needs here
//for example, you can sort on multiple columns, not just one
List<RowSorter.SortKey> sortKeys = new ArrayList<>();
//cycle through all orders; sort is removed every 3rd click
SortOrder order = SortOrder.values()[fCountClicks % 3];
sortKeys.add(new RowSorter.SortKey(columnIdx, order));
fSorter.setSortKeys(sortKeys);
++fCountClicks;
}
private int fCountClicks;
}
}
And did try this and getting same error.
btnNewButton.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
table.getRowSorter().toggleSortOrder(1);
}
});
Error:Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
This is the code: Code
This is the what program looks like : Picture

In the ActionListener of your JButton you can try sorting the column with code like:
table.getRowSorter().toggleSortOrder(columnIndex);
This should allow you to click the button to reverse the sort order each time it is clicked.
Edit:
As I said in my comment you need to learn how to solve a NullPointerException.
The stack trace when I run the code states:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at frame1$2.actionPerformed(frame1.java:83)
Line 83 is:
table.getRowSorter().toggleSortOrder(0);
So you have two variables at that statement:
table
table.getRowSorter()
It is up to you to determine which variable is null
So you add debug code before that statement:
System.out.println( table );
System.out.println( table.getRowSorter() );
If you do you will see that table.getRowSorter() returns null.
So now you can ask a proper question like:
"Why does table.getRowSorter() return null?"
The answer is simple you didn't set the properties of the table to do sorting.
This is easily done by adding:
table.setModel(model);
table.setAutoCreateRowSorter(true); // added
In the future do some basic debugging BEFORE asking a question. You can't code if you don't know the basics of debugging code.
My original answered assumed you new how to sort columns in a table when using the table header and you just wanted to know how to use a separate button. That is why a "MRE" should be posted with EVERY question so we don't have to guess what your code is really doing.

Hiding Multiple Elements in JTable via ButtonClick

I am currently working on a tool which edits data dynamically in a JTable. I want to hide the targeted row whenever a button is clicked. Right now I am using RowFilter. Whenever the button isClicked, a new filter is created:
RowFilter<MyTableModel, Object> rowFilter = null;
try {
rowFilter = RowFilter.notFilter(RowFilter.regexFilter(((String)dataTable.getValueAt(dataTable.getSelectedRow(), 0)),0));
} catch (java.util.regex.PatternSyntaxException e) {
return;
}
sorter.setRowFilter(rowFilter);
This only works for one element each time the button is clicked. I want to stay them hidden, so you can continously hide elemtens in the table. It is important to mention that I do not want to delete the rows, just hide them.
I hope someone has an easy answer for this, looking for quite a while now.

This method sorter.setRowFilter(rowFilter); is replacing the filter every time you "add" a new filter. So, it's "forgetting" the old rules. What you have to do is edit the existing filter to include the new rules for filtering.
Check out the documentation for more details.
In any case, I extracted a part of the documentation which you should try to implement.
From RowFilter Javadoc:
Subclasses must override the include method to indicate whether the
entry should be shown in the view. The Entry argument can be used to
obtain the values in each of the columns in that entry. The following
example shows an include method that allows only entries containing
one or more values starting with the string "a":
RowFilter<Object,Object> startsWithAFilter = new RowFilter<Object,Object>() {
public boolean include(Entry<? extends Object, ? extends Object> entry) {
for (int i = entry.getValueCount() - 1; i >= 0; i--) {
if (entry.getStringValue(i).startsWith("a")) {
// The value starts with "a", include it
return true;
}
}
// None of the columns start with "a"; return false so that this
// entry is not shown
return false;
}
};
This means that the include() method is going to return true or false depending if an item should be shown.
Therefore, you should only set the RowFilter once, and reimplment the include() method to match all the rules you currently have set upon your view.

JText string input, then display output to JList

I am pretty new in Java programming, I have been trying to solve this simple program
it reads user input, then the ADD button will simply display the typed string on the JList.
The remove button will simply remove the desired item in the JList.
I am quite confused how to put the action listener thing in the code, or get text whatever
it is. I'd really appreciate if you can help me solve this simple GUI.
It reads user input in JText (String) and when I click the add button (maybe action performed?) the String will be basically populated in JList. and the Remove button will
simply remove the selected String in JList.

Step 1
Bind the code to the specific event, using the addActionListener method.
button.addActionListener(new ActionListener({
public void actionPerformed(ActionEvent e)
{
// Bind the method to the button.
}
});
Step 2
Populate that method with the relevant code.
String value = jTextBox.getText();
// Grab the String value.
jListModel.addElement(value);
// And add it to the list model that informs the JList.
Altogether
button.addActionListener(new ActionListener({
public void actionPerformed(ActionEvent e)
{
String value = jTextBox.getText();
// Grab the String value.
jListModel.addElement(value);
// And add it to the list.
}
});
Useful Links
Here is a very good tutorial from Oracle detailing how to manipulate lists a million and one different ways.

Removing all Items from a combo box in Java

I need to remove all items from the combo box
int itemCount = combo.getItemCount();
for(int i = 0; i < itemCount; i++){
combo.removeItemAt(0);
}
This code will remove all items except the last one. It gives a NullPointerException.
How to fix that?

The code in the question would normally work. However, it looks like a threading issue. Another thread may be messing with the items.
However, I sugeest you should better use the removeAllItems(); method:
combo.removeAllItems();

How about JComboBox.removeAllItems()?

You can use
this.combo.removeAllItems();
to remove all the items in JComboBox.

In second line:
combo.removeItemAt(0);
I think instead of 0 it should be i.
do it in reverse order as:
for(int i=combo.getItemCount()-1;i>=0;i--){
combo.removeItemAt(i);
}
But in my case combo.removeAllItems() works fine

use .removeAllItems() methods to remove all items from combo box.

The assumption that it is related to another thread is not always true. It can be the thread itself causing the issue.
This exception may happen because an event is triggered when a combo item is removed and in this event handling method you still refer to combobox items.
For example when you delete somewhere (other than in actionPeformed()) in your code the last item from a combo box with combo.removeItemAt(0) or removeAllItems() then still the event actionPerformed will be fired/executed. But very often the actionPerformed() method contains code to react on user actions (user clicked somewhere on the combobox). So, when the last item has been deleted there is no more item in the combobox and any reference to an item or index in actionPerformed() will cause an exception.
The solution to this is to move the code from actionPerformed() to e.g. mouseClicked() or another event handler depending on what you want to do.

removeAllItems() it does remove all things but after the add data to the combo box it will not show there ,the nullPointException will shows

Use this to remove all the elements from the combo box :
DefaultComboBoxModel model = (DefaultComboBoxModel) ComboBox.getModel();
model.removeAllElements();

Usually it happens because you have an event associated JComboBox. It is solved if you have control item in the JComboBox to act, for example:
jComboBoxExample.addActionListener (new ActionListener () {
public void actionPerformed (ActionEvent e) {
do_run ();
}
});
public void do_run() {
int n=jComboBoxPerfilDocumentos.getItemCount(); <--THIS IS THE SOLUTION
if (n> 0) {
String x = jComboBoxPerfilDocumentos.getSelectedItem (). ToString ();
}
}

How to change selected value of a JComboBox

I have to two comboboxes, based on the selection made in the first combobox the selected value of the second box should change.
Please find the code snippet below:
secondcombobox.setSelectedItem(firstcombobox.getSelectedItem());

You should use an ActionListener:
firstcombobox.addActionListener(new ActionListener(){
void actionPerformed(ActionEvent e){
// sets the selected item of secondcombobox to be the value of firstcombobox
// assuming secondcombobox contains such a value.
secondcombobox.setSelectedItem(firstcombobox.getSelecteditem());
}
});
Note scoping here is important. You can either make firstcombobox and secondcombobox global or final, or you can use a slightly alternate form where you take those arguments as inputs to a constructor:
firstcombobox.addActionListener(new ActionListener(firstcombobox, secondcombobox){
private JComboBox a;
private JComboBox b;
public ActionListner(JComboBox a, JComboBox b){
this.a = a;
this.b = b;
}
void actionPerformed(ActionEvent e){
// sets the selected item of a to be the value of b
// assuming a contains such a value.
b.setSelectedItem(a.getSelecteditem());
}
});

Your code above will only work if the selected item in the first JComboBox also exists in the second JComboBox; In other words there exists an object in the second ComboBoxModel returns true when compared to the selected item from the first JComboBox.
If the selected item is not in the list, the method call will have no effect, which is suspect is what's happening in your case.

If your two comboboxes share the same values, you should use the same model for them both. It would be cleaner than to use an ActionListener.
DefaultComboBoxModel model = new DefaultComboBoxModel();
combo1.setModel(model);
combo2.setModel(model);
//init your values in the combo here
Then, when you select an item in one of the comboBoxes, it will be selected in the other.

Although your minimal question length makes your question cryptical, you will probably need:
firstcombobox.addActionListener() {
// Do something with secondcombobox
}