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Java Swing CardLayout: get componente associated to a String

is there a command that returns the componente associated to a speciefied String name in Java Swing CardLayout? I have many panels in my CardLayuot which are at first empty, at runtime i have to "update" those panels to add buttons in it (the panels already have GridBagLayout), i would prefer NOT to make panels all over again and replace the old ones, as it would be slower to charge, and instead get those panels and add something. Thanks guys! (i checked this but there's nothing like what i need https://docs.oracle.com/javase/7/docs/api/java/awt/CardLayout.html)

Every Component, such as JPanel, has a name field, and you can set it with setName(). If your program already has a List<JPanel>, you can search the list and check getName(). If not, you can add your panels to a Map<String, JPanel> and get() the one you want by name.

how do I re-use an action listener multiple times on a JTextField in java?

My program is supposed to get information about a person (first and last names, address, phone) so that it can add the person into an address book.
I made a JLabel which gives instructions on what to enter right below. Below the JLabel is a JTextField which has an ActionListener listening to what is being entered. My method has about 8 ActionListener's with 8 actionPerformed methods. I am running into trouble it is not working. I can't figure out any other way.

Best to create a form, perhaps with GridBagLayout or MigLayout that holds displays JLabel/JTextField pairs, so that the user can enter all the data on a single simple form, much like most software you use.
If you absolutely must use a single JTextField, then you should use a single ActionListener, but change how it responds based on the state of the GUI. That is, perhaps use an int counter variable, that you increment each time data is entered, and base what the listener does with the data based on the value held by the counter.

You can create an instance of the listener and reuse it across the class, like:
...
OnChangeListener listener = new OnChangeListener() {
//All the code here
};
...
textField1.addOnChangeListener(listener);
textField2.addOnChangeListener(listener);
textField3.addOnChangeListener(listener);
...

Returning variable to the second frame in Java

I have 2 frame in my one application. sum of two given number.
1st Frame: contains one JButton(will open 2nd frame) and one JLabel(print the return value from 2nd frame).
2nd Frame: contains two JTextField(For input two values) and one JButton(will sum the given values and return it to first frame or print it to JLabel of 1st frame).
Now My problem is I can not return the sum value from 2nd frame to 1st frame. What should I do? How can I get the sum value from 2nd frame.
Can anybody give me the sample code or any simple solution or may be any useful link????

Answer: don't use two JFrames. Instead, that second "frame" should be a modal dialog such as a JDialog or a JOptionPane. The reason this is important is that you'll make the second window appear from the first one, and the first window will know exactly when the user has finished dealing with the second window since program flow will resume right from the spot where it was initially set visible. It is then that the first window/class can query the second for the state of its variables and use them however it sees fit.

Both frames are objects.
The first frame can hold onto a reference to the second. The object representing the second frame is still accessible after the second frame is dismissed.
The second can store the sum in a field when the button is pressed. The first can access the sum via a method on the second.

Display a row of Strings on a JComponent so that the single Strings are selectable/their location getLocation()-able?

In order to be able to display a sentence on a, say, JPanel with a GridLayout(1,0) [i.e., only one line/row] and then be able to draw a syntax tree (or similar) above it, I want to display the sentence as a row of Strings, which each include one word.
The single Strings should then be either selectable (as in a JList), or I should at least be able to get their Location on the JPanel via getLocation().
Up to this point I have tried the following options, and had the following issues:
- Single Strings as JLabels: The JLabels are stretched out to fill the JPanel width, re-sizing them to fit the single String they're displaying seems complicated. I would want to be able to do this, however, to make the sentence look like a sentence and not like a badly layed out table.
- JList: All the functionality I want, but I'm unaware of an option to re-size the "cells" of a single String (cf. JLabel above). Also, I'm having difficulties restricting display of the JList to a single line/row (cf. another of my questions).
- JTextArea: I couldn't get my head round how to get the Location of the single Strings that I had appended to the JTextArea.
I'm aware that drawString() might be an option, but I'm afraid to use it since I don't want to mix AWT and Swing. Also, I would need to calculate the int values for x and y for every single String. And I'm not sure whether I'd be able to get their Locations at all (although I could of course save their ints in a Map or Vector since I have to calculate them anyway).
Thankful for any suggestions! Thanks!

I would use JTextArea and method modelToView()/viewToModel() to get x,y for position in nthe string and position in the string for coordinates x and y.
Also use Utilities class getWordStart() getWordEnd() getRowStart() getRowEnd() methods.

EDIT: As noted by camickr in the comments, setSize() is not an appropriate way to lay out Components (as this is automatically done by the respective LayoutManager, I have removed the respective code from my answer.
Triggered by StanislavL's answer, I have found a solution to do it via JTextField, albeit by using one for each String rather than just one (as suggested by StanislavL).
I can now easily getLocation() for each JTextField. Simple, really!
I'd like to thank StanislavL for his answer, without which I'd never have though about this, and camickr for his comment.

Showing the previous tab of CardLayout

I'm having trouble figuring this one out.
The situation is no difficult to imagine so I hope I could post this without a sample code.
I have JPanel with CardLayout. The panel contains several other panels as individual tabs. What I'm trying to achive is to create a JButton that will make the main panel show last opened tab (the one before the current was shown). No big deal I thought at first.
So I started by thinking how to get the current visible tab (panel) and found out that there is no native method for that in Panel or rather CardLayout that only contains methods first(), last(), next() and previous() which are no use to me.
Then I thought that maybe to achive my goal I might go through all components of the main panel and test which one is visible which would be the current one. I find it a little complicated, fine, but how do I make this panel show by CardLayout if I don't have its card name to call CardLayout method show(parent, name)?
At this point, I have no idea. I've been searching over the Internet but haven't found a solution, only that few people have been trying to figure something similar out.
So I hope someone who already delt with this kind of issue comes across this topic :-)
Thanks for any suggestions.
Best regards
Martin S.

This brings up the question of how you arrived at the current card in the first place. If you used next() to get to the current card, then previous() will get you to the previous card and vice versa. If you use first() or last(), then you're out of luck.
Of course, you could always duplicate some of the information stored by the CardLayout to achieve your goal: if you maintain an array of component names (and update it whenever you call addLayoutComponent) as well as a previous index (and update this with next, previous and other calls), then you can just lookup the name of the previous component and use show to show the previous card.
Update: Since you know the tab names, here's how you can maintain the previous tab name:
String prevTab, curTab;
public void showTab(String newTab) {
prevTab = curTab;
curTab = newTab;
layout.show(parent, curTab);
}
public void goBack() {
layout.show(parent, prevTab);
}

You can create a map object Map. And add panels & names to card layout and to the map. Afterwards, if you have the previously shown JPanel, you get its' name from map via map.get(JPanel p).
And to find what JPanel was visible before the moment, you'll need to add ComponentListener to each JPanel. And make it to change some static variable on componentHidden event (e.g. static JPanel prev_shown).