i write a method to create a form(3 buttons and a textBox), then i call it in main.
but when i run program, before i enter information in the form (method form6 ),
Other commands that are executed! "s4 and ontname chenged in the form".
this is a part of my code:::::::::::
//////////////////////////////////////////////////////////////////////////
public static void main(String[] args) {
System.out.println("*begin main*"); // call form method
String s4= form6(); // s4 is returned by method.
System.out.println("s3333*"+s4);
System.out.println("ont:"+ontname);//it's global }
//////////////////////////////////////////////////////////////////////////
i have 2 questions:::
1--- While the form is running, other commands are executed!
What is their order execution?
2. --- i want to define a button to when i click it,it closes the form.
thanks all.
If I get your code correctly, ontname is either (1) a class member (declared outside a method) or (2) a local variable, which is declared in the method that contains this code snippet.
In both cases there is no need to "return" ontname just because it is not declared inside the anonymous ActionListener instance.
The following example illustrates a typical pattern for this problem:
public void someMethod() {
// ...
button2.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
String filename = File.separator+"c:";
JFileChooser fc = new JFileChooser(new File(filename));
fc.showOpenDialog(null);
File selFile = fc.getSelectedFile();
setOntName(selFile.getPath()); // <-- here we call another method
}
});
// ...
}
void setOntName(String ontName) {
// do something with ontName
}
Alternativly: declare ontName as a static class member (only):
private static String ontName = ""; // <-- accessible from main method
public static void main(String[] args) {
// ...
}
// more methods.
You can't return a value in this Method because the ActionListenerInterface does not allow this. But you can call another method from within the actionPerformed() method and pass the ontname to it.
You can also close the third button in the new method. Or define the third button as final and use it in the actionPerformed() method.
E.g.
button2.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
String filename = File.separator+"c:";
JFileChooser fc = new JFileChooser(new File(filename));
fc.showOpenDialog(null);
File selFile = fc.getSelectedFile();
ontname=selFile.getPath();
System.out.println("filepath: "+ontname); //it works correctly.
anotherMethod(ontname);
}
});
private void anotherMethod(String path) {
//doSomething with the path
//close third button here
}
You could probably define your variable ontname as global, outside of your function:
var ontname = null;
button2.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
// ...
ontname=selFile.getPath();
}
});
// ...
System.out.println("filepath: "+ontname);
If you want to remember the values, then they should be class level variables.
But, generally, you would want to pass these to some other method to do some processing on them (or, say, persist them in a file). You can pass these as parameters to the other method.
(The second one is better in most cases, I don't know much about your app, so I am unable to give one answer)
There are other problems with your code:
You need to check whether the use has clicked the "Ok" or "Cancel" button in the open dialog to decide whether to get the file or not.
String filename = File.separator+"c:"; does not really make sense. Perhaps you meant String filename = "c:"+File.separator; But even this is not very useful. File.separator is for getting the platform specific file separator char (\ in Windows, / on linux) but since you are hard coding c:, you are anyway constrainting your app to Windows. You might want to have a better platform independent way (start at the "default" path, new JFileChooser() without arguments, and then remember the path the user last used, and proceed from there)
If the argument to the showOpenDialog method is your parent frame, then the dialog would be centered on the parent frame, and would, in most cases, look nicer.
You might also want to relook your variable names.
button2.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String filename = File.separator+"c:";
JFileChooser fc = new JFileChooser(new File(filename));
int option = fc.showOpenDialog(null);
if(option = JFileChooser.APROVE_OPTION)
{
File selFile = fc.getSelectedFile();
String ontname=selFile.getPath();
System.out.println("filepath: "+ontname); //it works correctly.
doSomeOperation(ontname); //Or, declare ontname as a class level variable.
}
}
});
Related
Can I make anonymous event handler method to act conditional like
JButton activeDataBtn = new JButton("Active");
activeDataBtn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
if (activeDataPanel.setVisible(false)) { //Erroneous code
readDataFromFile(); //a method reads data from .csv
//file and shows it on activeDataPanel
activeDataPanel.setVisible(true);
}
else
activeDataPanel.setVisible(false);
}
}
});
how can i make this conditional?
Sure you can, but that code is not valid:
if (activeDataPanel.setVisible(false))
maybe you want to check if your panel is visible try it this way:
if (activeDataPanel.isVisible())
or maybe activeDataPanel.getVisible() I'm not sure about the getter name for it right now :)
I want to call the return statement tempimage in load_picture by passing it to showWindow, but I'm not sure how. heres a snippet of my code. edit:
i guess what I'm trying to say is, I'm not exactly sure what to do with the hardcoded "picture1.gif". I understand that I need to call a method to load the image, but I'm not too sure what to put in place of it.
:
package project3;
import java.util.Scanner;
import javax.swing.;
import java.awt.;
import java.net.*;
public class Project3 {
//initializing global
static Project3 theobject = new Project3();
final static int MIN_NUMBER=1;
final static int MAX_NUMBER=8;
static int image_number=1;
static Image theimage;
// This routine will load an image into memory, non-static requires an object
// It expects the name of the image file name and a JFrame passed to it
// It will assume an Internet conection is available
// It can only be called AFTER the program object has been created
// It will return a type Image variable, call it like this: theimage = object.load_picture("picture1.gif", frame);
// (hard code 'picture1.gif' only when testing - USE a method or variable for 'real' call)
// This code requires you to do an 'import java.awt.*' and an 'import java.net.*'
// Note: this method is using parameter and return type for input/output
// This routine will load an image into memory, non-static requires an object
// It expects the name of the image file name and a JFrame passed to it
// It will assume an Internet conection is available
// It can only be called AFTER the program object has been created
// It will return a type Image variable, call it like this: theimage = object.load_picture("picture1.gif", frame);
// (hard code 'picture1.gif' only when testing - USE a method or variable for 'real' call)
// This code requires you to do an 'import java.awt.*' and an 'import java.net.*'
// Note: this method is using parameter and return type for input/output
public Image load_picture(String imagefile, JFrame theframe)
{
Image tempimage;
// Create a MediaTracker to inform us when the image has
// been completely loaded.
MediaTracker tracker;
tracker = new MediaTracker(theframe);
// getImage() returns immediately. The image is not
// actually loaded until it is first used. We use a
// MediaTracker to make sure the image is loaded
// before we try to display it.
String startURL;
if (imagefile.startsWith("http"))
startURL = "";
else
startURL = "http://www.canyons.edu/departments/comp_sci/ferguson/cs111/images/";
URL myURL=null;
try
{
myURL = new URL(startURL + imagefile);
}
catch(MalformedURLException e) {
System.out.println("Error caught " + e.toString());
}
//tempimage = getImage(myURL); // JApplet version
tempimage = Toolkit.getDefaultToolkit().getImage(myURL); // stand alone program version
// Add the image to the MediaTracker so that we can wait for it
tracker.addImage(tempimage, 0);
try { tracker.waitForID(0); }
catch ( InterruptedException err) { System.err.println(err); }
return tempimage;
}
// This class/method uses a global variable that MUST be set before calling/using
// note: You can not call the paint routine directly, it is called when frame/window is shown
// look up the repaint() routine in the book
// Review Listings 8.5 and 8.6
//
public static class MyPanel extends JPanel {
public void paintComponent (Graphics g) {
JPanel panel= new JPanel();
int xpos,ypos;
super.paintComponent(g);
// set the xpos and ypos before you display the image
xpos = 300; // you pick the position
ypos = 200; // you pick the position
if (theimage != null) {
g.drawImage(theimage,xpos,ypos,this);
// note: theimage global variable must be set BEFORE paint is called
}
}
}
public static void showWindow( String filename ) {
// create, size and show a GUI window frame, you may need to click on taskbar to see window
//display the filename in the title of the window frame, otherwise the window will be blank (for now)
JFrame frame1= new JFrame();
theimage = theobject.load_picture("picture1.gif", frame1);
//"picture1.gif" is hardcoded, I want to call this using a method
frame1.setTitle(filename);
frame1.setSize(440,302);
frame1.setLocation(400,302);
frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame1.setVisible(true);
}
Any help is appreciated. Thanks
The value that is returned by the load_picture method can be sent directly to the showWindow method, or you can assign it to a variable:
String filename = "your/filename";
JFrame theFrame = new JFrame();
Project3 project = new Project3();
MyPanel.showWindow(project.load_picture(filename, theFrame);
From within the showWindow method, just call the load_picture method as follows:
Image tempImage = load_picture(filename, frame1);
From here you can do anything you like with the tempImage object.
statsButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e){
//Return the string "stats" to gameLoop() as cmd
}
});
public void gameLoop(){
Scanner lineScanner = new Scanner(System.in);
cmd = "";
System.out.print(getBoard().printBoard(false));
while (!cmd.equals("quit")) {
System.out.print(">");
Scanner wordScanner = new Scanner(lineScanner.nextLine());
if (wordScanner.hasNext()) {
cmd = wordScanner.next();
if (cmd.equals("board")) {
System.out.print(getBoard().printBoard(false));
} else if (cmd.equals("ships")) {
System.out.print(getBoard().printBoard(true));
} else if (cmd.equals("help")) {
printHelp();
} else if (cmd.equals("stats")) {
printStats();
} else if (cmd.equals("fire")) {
if(fire(wordScanner)) {
printStats();
cmd = "quit";
}
} else if (cmd.equals("quit")) {
} else if (!cmd.equals("")) {
System.out.println(ILLEGAL_COMMAND);
}
}
}
}
What I'm trying to do is that when the user clicks the statsButton, the String cmd in the gameLoop would be changed to "stats". The statsButton and the gameLoop() are located in two different classes. Anyone can give me an idea how to do it? (I've attempted pipedreader/pipedwriter) and I just can't seem to get it right.
*I'm basically trying to make my console application into a GUI application without changing the original console application.
Edit: What I've tried
Class textBased
PipedInputStream in = new PipedInputStream()
public void gameLoop(){
try{
in.connect(GUIclass.out);
Scanner lineScanner = new Scanner(in);`
Class GUIclass
PipedOutputStream out = new PipedOutputStream();
PrintWriter writer;
public GUIclass(){
final PrintWriter writer = new PrintWriter(out);
statsButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e){
writer.println("stats");
}
});
that's what I tried writing but it doesn't seem to work.
Regarding
I'm basically trying to make my console application into a GUI application without changing the original console application..."
My advice is simple: "don't do it".
The two applications have completely different structure, one being linear, the other being event-driven, and are not directly translatable to each other. Better to make a new GUI program from the ground up. Now if your non-GUI application contains some well-structured and behaved object-oriented classes, then by all means use those classes in your GUI's "model" or logic section, but don't try to directly translate the program flow of one type of application to the other.
Edit
Based on your posted requirements:
"You should be able to play your Battleship game through your GUI interface. In addition, the text-based front-end you wrote for project 1 should still "work" and be playable."
Correct me if I'm wrong, but I'm betting that you have several classes involved here, and only one of them is the "text-based front-end". If so, then use the non front-end classes as the model of your GUI as I suggested above, but do not use the text-based front-end for anything GUI related, and do not try to emulate it in your GUI.
Have the console application instantiate the button ActionListener and pass it to the UI. When the action event is fired, the listener will tell the console app that it happened. The method in the ActionListener will tell it what to do.
I agree with Hovercrafts comment (changed to a reply).
But in general for problems like this I would change the method signature of your gameLoop(). I would use:
public void gameLoop(Reader reader)
Then you can pass different types of readers to the loop depending on the requirement.
For a console you might do something like:
gameloop( new InputStreamReader( System.in ) );
For a GUI you could do something like:
gameLoop ( new StringReader("some text") );
Edit:
Without changing the method signature you can redirect System.in to come from the String retrieved by the ActionListener:
public class Test
{
public static void main(String args[]) throws Exception
{
String text = "some text";
System.setIn( new ByteArrayInputStream( text.getBytes() ) );
// gameloop();
Scanner lineScanner = new Scanner(System.in);
System.out.println( lineScanner.nextLine() );
}
}
If you have something like this :
class B {
public void gameLoop(){
..
}
}
and
class A{
statsButton.addActionListener(new ActionListener() {
...
});
}
You can declare reference to B in A with final . In that case it's will be visible in inner class ActionListener.
class A{
final B b = ...; //final variable is visible in inner class
statsButton.addActionListener(new ActionListener() {
b.gameLoop();
...
});
}
I'm making a program that adds and formats files. I actually have many classes, but for the purpose of this question let's say I have two, guidialog and guimain.
In guidialog I have a JTextField and an actionlistener for it. Here is the actionlistner:
public void actionPerformed(ActionEvent event) {
blockName=textFieldBlockName.getText();
System.out.println("Made new block: "+blockName);
canClose=true;
guimain blockAddWrite = new guimain();
blockAddWrite.addNewBlockFile();
}
});
public String blockName;
Now in guimain I have a formatter which writes a file based on the name given in the text field:
public void addNewBlockFile() {
blockdialog blockName = new blockdialog();
try {
newBlock = new Formatter("Block" + blockName.blockName + ".java");
System.out.println("Created File: Block" + blockName.blockName);
} catch (Exception e) {
System.out.println("ERROR: Could Not Output Block File");
}
}
I do edit and close the file, but it wasn't necessary. But when I try this, all of the stuff in guimain that refers to blockName outputs as "null". I can't figure it out.
That's because in guimain, you're not using the blockName field of the dialog where the user entered something: you're using the blockName field of another, newly constructed dialog:
public void addNewBlockFile() {
blockdialog blockName = new blockdialog();
^--- the dialog is not the one where the user entered something. It's a new one.
You should pass the blockName from the dialog to the guimain:
public void actionPerformed(ActionEvent event) {
blockName=textFieldBlockName.getText();
System.out.println("Made new block: "+blockName);
canClose=true;
guimain blockAddWrite = new guimain(blockName); // we construct a guimain instance with the entered text
blockAddWrite.addNewBlockFile();
}
});
Side notes:
you should not use public fields. Use getter methods.
classes should be start with an upper-case and be spelt in CamelCase: GuiMain.
hi i have a full screen program which i dont want people to close unless they have a password i have this code at the moment
public void windowClosing(WindowEvent arg0)
{
System.out.println("HERE");
String inputValue = JOptionPane.showInputDialog("Please input the closeword");
if (inputValue != "closeplz")
{
}
}
in the if statement i want it to stop the method so that the program doesent close. any help would be greatly aprecheated thanks ste
You have to call
setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
on (or within) the JFrame instance. Then the frame will not close unless you do it manually, though windowClosing() will still be called. Inside it, you can then conditionally call
System.exit(1);
which will end the application. Be sure to do any necessary cleanup first.
Check out Closing an Applicaton for a simple class to help you with this. You would need to provide the custom close action that prompts the user for the password.
Using your simple example the code would be:
Action ca = new AbstractAction()
{
public void actionPerformed(ActionEvent e)
{
JFrame frame = (JFrame)e.getSource();
String inputValue = JOptionPane.showInputDialog("Please input the closeword");
if (! inputValue.equals("closeplz"))
{
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
}
}
};
CloseListener cl = new CloseListener(ca);