Is there a way to make things happen if a certain text is entered in a TextField?

**DusteroftheCentury** · January 22nd, 2012, 12:33 AM

Hey,

First of all please excuse my lack of technical terms.

I want to have a JTextField be able to accept commands, and have the commands change pictures, display text etc.

Is their a simple way to do this?

Thanks in advance,

-Duster

(If you need the code, just ask)

**elisha.java** · January 22nd, 2012, 12:36 AM

Originally Posted by DusteroftheCentury

Hey,

First of all please excuse my lack of technical terms.

I want to have a JTextField be able to accept commands, and have the commands change pictures, display text etc.

Is their a simple way to do this?

Thanks in advance,

-Duster

(If you need the code, just ask)

I would suggest reading java docs GUI tutorials and methods that fall into that concept. Try something that comes to your mind, if you fail, try again and then post errors you receive here.

**DusteroftheCentury** · January 22nd, 2012, 12:38 AM

300zek0.pngThis image might help better explain what I want:

**DusteroftheCentury** · January 22nd, 2012, 12:39 AM

Originally Posted by elisha.java

I would suggest reading java docs GUI tutorials and methods that fall into that concept. Try something that comes to your mind, if you fail, try again and then post errors you receive here.

Didnt see your post there. I shall try.

**DusteroftheCentury** · January 22nd, 2012, 01:06 AM

Here is my code so far:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
 
public class MainClass extends JFrame implements ActionListener
{
	public static void main(String[] args)
	{
		new MainClass();
	}
		private JButton button1;
		private JLabel label1;
		private JTextField textbox1;
 
		public MainClass()
		{
		JPanel panel1 = new JPanel();
		{
		button1 = new JButton("OK");
		ButtonListener b1 = new ButtonListener();
		JLabel label1 = new JLabel();
		JTextField textbox1 = new JTextField(15);
		textbox1.getText();
		textbox1.addActionListener(this);
 
		panel1.add(textbox1);
		panel1.add(label1);
		panel1.add(button1);	
 
		this.add(panel1);
		this.setSize(300,100);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setVisible(true);
	}
}
 
	private class ButtonListener implements ActionListener
	{
	public void ActionPerformed1(ActionEvent e)
	{
		if (e.getSource() == button1);
		{
 
			if (e.getSource() == button1);
			//Code to check if the command the commands goes here?
			}
		}
	}
 
	public void ActionPerformed2(ActionEvent f)
	{
		if (f.getSource() == textbox1);
		{
 
			if (f.getSource() == textbox1);
				//Or here? 
			}
	}		
}

Am I heading in the right direction? I checked the Java docs GUI tuts and from what I could gather this is where I should be going.

In the places where i specified where the code might go what code would I put in there? The Gui docs tut just shows how to add the ActionListener, not how to use it.

Thanks for the help,

-Duster

**chronoz13** · January 22nd, 2012, 12:33 PM

Entering "Banana" and hitting "ok" would display a picture of "DANCING" banana

so far your codes seems right, but your not even half way to what you want

1.) By looking at your codes, Entering words and listening to the actions can be done
2.) Displaying a picture
- Start with how to paint images in a Light weight component
3.) Dancing Banana
- How do you want the banana to dance?
- Rolling, Blinking, (im not sure what you want)
- start with simple java animations
- start with no.2, youre on the right track from painting images to animating simple things

hope this helps

**DusteroftheCentury** · January 22nd, 2012, 01:27 PM

I just want it to add a pic to the panel by using ImageIcon. This is the image: PBn'J.gif

How would I listen to the actions? I know I can do "textbox1.getText();" to retrieve the text, but what code do I add to make it listen to that text and check if it is a command?

Also where would it go?

Thanks for your help,

-Duster

**Manoj Kumar Chhetri** · January 22nd, 2012, 03:51 PM

I have made a solution . May it work for you

First you need to enter "banana" as a command to the text field shown below
Untitled.png

Now Click on "Click" Button You will get below image .. which make u happy

Untitled2.jpg

Code:-
package pack;

import java.awt.Image;
import java.awt.event.ActionListener;

import javax.swing.*;

public class letsDance extends JFrame {

private static final ActionListener ActionListener = null;

public static void main(String[] args) {
new letsDance();
}

private JButton clickButton;
private JTextField commandField;

public letsDance() {
JPanel panel1 = new JPanel();
{
clickButton = new JButton("Click");
clickButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
clickButtonActionPerformed(evt);
}
});

commandField = new JTextField(15);
commandField.setToolTipText("Enter the command");

panel1.add(commandField);
panel1.add(clickButton);

this.add(panel1);
this.setSize(300, 100);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );
this.setVisible(true);
}
}
private void clickButtonActionPerformed(java.awt.event.ActionEv ent evt) {

if(commandField.getText().toString().equals("banan a"))
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOS E);
//provide the right image location in your local machine as i provided "C:/manojworkspace/BananaDancing/src/image/Dancing_Banana.gif"
ImageIcon icon = new ImageIcon("C:/manojworkspace/BananaDancing/src/image/Dancing_Banana.gif");
Image normalImage = icon.getImage();
Icon ic = new ImageIcon(normalImage);
JLabel label3 = new JLabel("Banana Dancing", icon, JLabel.CENTER);
frame.add(label3,"North");

frame.setSize(600, 300);
frame.setVisible(true);

}
else{
// add as your need
}
}

}

**copeg** · January 22nd, 2012, 04:32 PM

Manoj Kumar Chhetri, please read the forum rules. I would also highly recommend that you read following:
The Problem with Spoon-feeding
I am stopping short of removing your code, but that does not mean another moderator won't come along and do so.

**DusteroftheCentury** · January 22nd, 2012, 08:16 PM

I appreciate this but I understand that spoon feeding is bad. I only needed a few lines of that and that is what I will use.

Thank you.

@copeg I understand, I accidentally spoon fed someone this morning, before I knew it was wrong.

-Duster

**chronoz13** · January 22nd, 2012, 10:01 PM

-_-, i never thought of a GIF image -_-, i was thinking you want to create the sprites and animation manually, well there you go.

**DusteroftheCentury** · January 22nd, 2012, 11:05 PM

I really dont want to just use the code given, I want to figure it out with help.

Here is my new code:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.JFrame;
 
public class MainClass extends JFrame 
{
	public static void main(String[] args)
	{
		new MainClass();
	}
 
		private JLabel label1;
		private JTextField textbox1;
 
		public MainClass()
		{
		JPanel panel1 = new JPanel();
		{
 
		JLabel label1 = new JLabel();
		JTextField textbox1 = new JTextField(15);
		textbox1.getText();
		textbox1.setToolTipText("Enter commands");
 
		panel1.add(textbox1);
		panel1.add(label1);
 
 
 
		this.add(panel1);
		this.setSize(300,100);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setVisible(true);
	}
}
 
 
	public void ActionPerformed2(ActionEvent f)
	{
		if (textbox1.getText().toString().equals("banana"))
			{
			JFrame frame1 = new JFrame();
			frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
			ImageIcon pic = new ImageIcon(MainClass.class.getResource("PBn'J.gif"));
			frame1.add(new JLabel(pic));
 
		}		
	}
}

When I type "banana" and hit enter, nothing happens. No errors messages either. Do I need to add an action listener? if so, how would I do that in this instance?

Thanks for helping

-Duster

**copeg** · January 23rd, 2012, 10:10 AM

Yes you need a listener of some sort - an ActionListener your best bet (which you can add to a JTextField). See How to Write an Action Listener (The Java™ Tutorials > Creating a GUI With JFC/Swing > Writing Event Listeners)

**Manoj Kumar Chhetri** · January 23rd, 2012, 02:12 PM

@moderator

I sorry for what i did . Actually i am new to this forum and some of the post i have seen others providing solution using code snippets ...So that's why i did ..

But if i will not provide snippets, how would i able to give my solution ? If you recommend suggestion in terms of providing links and some comments, So its just become a long thread of a clarification/queries chain and just the wastage of time.

Personally i do believe in open source ethics "share and learn".

**copeg** · January 23rd, 2012, 03:26 PM

Originally Posted by Manoj Kumar Chhetri

@moderator

I sorry for what i did . Actually i am new to this forum and some of the post i have seen others providing solution using code snippets ...So that's why i did ..

But if i will not provide snippets, how would i able to give my solution ? If you recommend suggestion in terms of providing links and some comments, So its just become a long thread of a clarification/queries chain and just the wastage of time.

Personally i do believe in open source ethics "share and learn".

Please check your private messages. Lets leave this discussion outside this thread for fear of getting off the main topic at hand.

**DusteroftheCentury** · January 23rd, 2012, 08:25 PM

Thanks, I checked the link and touched up on ActionListeners. I wrote this code,

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.JFrame;
 
public class MainClass extends JFrame implements ActionListener
{
	public static void main(String[] args)
	{
		new MainClass();
	}
 
		private JLabel label1;
		private JTextField textbox1;
		private JButton button1;
 
		public MainClass()
		{
		JPanel panel1 = new JPanel();
		{
 
		JLabel label1 = new JLabel();
		JTextField textbox1 = new JTextField(15);
		textbox1.getText();
		textbox1.addActionListener(this);
		textbox1.setToolTipText("Whats the password?");
		button1 = new JButton("OK");
		button1.addActionListener(this);
 
		panel1.add(textbox1);
		panel1.add(button1);
		panel1.add(label1);
 
 
 
		this.add(panel1);
		this.setSize(300,100);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setVisible(true);
	}
}
 
 
	public void actionPerformed(ActionEvent e)
	{
		if (e.getSource() == button1)
			{
			if (textbox1.getText().equals("password"))
				System.out.println("You sir are a good guesser.");
 
		}		
	}
}

And it produces this error message:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at MainClass.actionPerformed(MainClass.java:48)
	at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
	at java.awt.Component.processMouseEvent(Unknown Source)
	at javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
	at java.awt.EventQueue.access$000(Unknown Source)
	at java.awt.EventQueue$3.run(Unknown Source)
	at java.awt.EventQueue$3.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)

Please help, not sure what is wrong with my code.

Thanks,

-Duster

**copeg** · January 23rd, 2012, 08:30 PM

What is null on that line of code? Add some println's in there to see (hint: where do you initialize the instance variables?)

**DusteroftheCentury** · January 23rd, 2012, 08:49 PM

Could you explain what null means? And what kind of printlns? I know they can be used to catch exceptions but how?

Thanks for the help,

-Duster

**copeg** · January 23rd, 2012, 10:08 PM

Originally Posted by DusteroftheCentury

Could you explain what null means?

null means an object has not been instantiated. In the following code...

String myValue;

...myValue will be null.

Originally Posted by DusteroftheCentury

And what kind of printlns? I know they can be used to catch exceptions but how?

Thanks for the help,

-Duster

Simply print out to the terminal (eg System.out.println). It allows you to inspect the value of a variable, and is one of the many invaluable debugging techniques (see http://www.javaprogrammingforums.com...t-println.html ). The exception stack trace tells you the method that throws the exception (and even the line it occurs on), so you can print the values of some variables you access prior to where the exception is thrown to see which is null, the backtrack to investigate why (and keep in mind my hint above). I am not trying to torture you by not telling you exactly what is wrong, because learning how to determine what is wrong is an important skill to learn.

**DusteroftheCentury** · January 23rd, 2012, 10:31 PM

What lines of code would you reccomend checking? And how? I understand your blog, but I do not see how that would apply here, because I dont really use numbers and integers and such, which if I did I would know how to check. However I dont know how to check text variables.

Thanks for helping a beginner,

-Duster

**copeg** · January 24th, 2012, 10:40 AM

Originally Posted by DusteroftheCentury

What lines of code would you reccomend checking? And how? I understand your blog, but I do not see how that would apply here, because I dont really use numbers and integers and such, which if I did I would know how to check. However I dont know how to check text variables.

Thanks for helping a beginner,

-Duster

Read the exception:

at MainClass.actionPerformed(MainClass.java:48)

Looks like line 48 of your MainClass.

PrintStream (System.out) contains print statements for all sorts of data types, not just primitives. To reiterate, go to the line of code above and inspect the value of the variables used in that line. For instance, you could write

System.out.println(textbox1);

What does it print?

**DusteroftheCentury** · January 24th, 2012, 08:27 PM

It prints this:

javax.swing.JTextField[,0,0,0x0,invalid,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=javax.swing.plaf.BorderUIResource$CompoundBorderUIResource@25b80053,flags=296,maximumSize=,minimumSize=,preferredSize=,caretColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],disabledTextColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],selectionColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],columns=15,columnWidth=0,command=,horizontalAlignment=LEADING]

Thanks for helping,

-Duster

**Mr.777** · January 25th, 2012, 05:04 AM

Originally Posted by DusteroftheCentury

It prints this:

javax.swing.JTextField[,0,0,0x0,invalid,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=javax.swing.plaf.BorderUIResource$CompoundBorderUIResource@25b80053,flags=296,maximumSize=,minimumSize=,preferredSize=,caretColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],disabledTextColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],selectionColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],columns=15,columnWidth=0,command=,horizontalAlignment=LEADING]

Thanks for helping,

-Duster

NO. In your previous last given code, you have actually declared textbox1 as instance variable and then in constructor, you re-declare and initialize it as a local variable, so the instance variable is actually shadowed but still null. Just remove the declaration inside the constructor and the code will work fine.

**DusteroftheCentury** · January 25th, 2012, 07:46 PM

What line do I remove? Sorry Im just not very familiar with the many technical terms.

Thank you so much,

-Duster

**Mr.777** · January 26th, 2012, 12:07 AM

JTextField textbox1 = new JTextField(15);

Instead of this, just write

textbox1 = new JTextField(15);

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