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Thread: How to build more actions in exicting code. A continum problem.

  1. #1
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    Default How to build more actions in exicting code. A continum problem.

    Firstly-Sorry about my spelling

    I'm trying to code, produce, calculating ''machine'' (hahaha) and I've tried various things(?). If else-statement.....blabla....see the text in yellow.

    I'm trying to build on existing code that is working fine, the plus action is working. I'm trying to build more actions in it like a minus function...for starters. What I need is a sugestions on how to proceed This is the error I get in the Eclipse console:

    at java.awt.EventQueue.dispatchEvent(EventQueue.java: 693)
    at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:244)
    at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:163)
    at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:151)
    at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:147)
    at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:139)
    at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:97)


    mport java.applet.Applet;// The code starts here.
    import java.awt.*;
     
    	public class Reiknivel extends Applet // Reiknivel means calculator machine
    	{
    		/**
    		 * 
    		 */
    		private static final long serialVersionUID = 1L;
    		TextField t1, t2, tsvar;// svar means answer
    		Button bplus; Button bminus;
    		Label a1, a2, b3;
    		Double D1, D2;
    		double d1, d2, dsvar;
     
    		public void init()
    		{
    			t1 = new TextField(3);
    			t2 = new TextField(3);
    			tsvar = new TextField(15);
    			bplus = new Button("+");
    			bminus = new Button("-");
    			a1 = new Label ("Tala 1");//means number 1
    			a2 = new Label ("Tala 2");//means number 2
    			b3 = new Label ("Samanlagt");
     
    			this.add(a1); 
    			this.add(t1);
    			this.add(bplus);
    			this.add(bminus);
    			this.add(a2);
    			this.add(t2);
    			this.add(b3);
    			this.add(tsvar);
    		}
     
    		public boolean action(Event e,Object o)
    		{
    			if (e.target == bplus);
    			{
     
    			D1 = new Double(t1.getText());
    			d1 = D1.doubleValue();
    			D2 = new Double(t2.getText());
    			d2 = D2.doubleValue();
    			dsvar = d1 + d2;
    			tsvar.setText("Summan er: " + dsvar);
    			return true;
    		}
    		return false;// Here ends the original code. And it works just fine.[COLOR="#FFD700"] AND HERIN LIES MY PROBLEM. The thing that I'm trying to ''produce'' is to add -, * , / ...buttons and actions or functions        [/COLOR]
    		}
    		public boolean action2(Event e,Object o)// I'm trying to continue here
    		{
    			if (e.target == bminus);
     
     
    			D1 = new Double(t1.getText());
    			d1 = D1.doubleValue();
    			D2 = new Double(t2.getText());
    			d2 = D2.doubleValue();
    			dsvar = d1 - d2;
    			tsvar.setText("Summan er: " + dsvar);
    			return true;
    		}
    	}
    Last edited by jps; August 5th, 2013 at 07:14 PM. Reason: code tags


  2. #2
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    Default Re: How to build more actions in exicting code. A continum problem.

    Please use code tags when posting code, assistance can be found on the Announcements page

    Beware that placing a semicolon after an if statement "ends" the condition and the following statements will always be executed
    if(false);//if ends here
    {
       System.out.println("this will print");
    }

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    einar123 (August 6th, 2013)

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    Default Re: How to build more actions in exicting code. A continum problem.

    If you're trying to run the code you've posted (with the first 'mport' fixed), you should be seeing a red squiggly under this line:

    return false;// Here ends the original code. . . . (Line 50 to me)

    If you put your cursor on the red squiggly, a tool tip-like message will appear to tell you why it's there, hinting at the problem jps highlighted above. If you correct the mistake that jps pointed out, then the red squiggly should go away.

    Why are you using Applet instead of the more modern Swing version, JApplet?

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    einar123 (August 6th, 2013)

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    Default Re: How to build more actions in exicting code. A continum problem.

    Einar123,
    You know what action2() is?
    But does JVM know when is it supposed to exeucte action2()? If not do you think you can tell JVM somehow to consider action2() also?
    If not then what is the solution?
    Sometimes JVM does not listen to us. We will have to listen to what it says.
    You don't have to define any extra action methods. Intelligently put your extra code in the single action() and try to get the output.

    Syed.

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    einar123 (August 6th, 2013)

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    Default Re: How to build more actions in exicting code. A continum problem.

    Hahah, thank you GregBrannon. I'm using an old textbook-but it is my language icelandic. I have no idea what Swing version, JApplet is. I also have a 2012 textbook: Java HOW TO PROGRAM by Paul Deitel but it's a bit overwhelming at first so I'm using this old book to start with...and it's fun

    --- Update ---

    Thank you jps. Code tags. I will try next timež. Thanks

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    Default Re: How to build more actions in exicting code. A continum problem.

    JApplets were included in Swing in Java 1.1 or 1.2 (fuzzy historical references, and I wasn't there).

    Applets are AWT (not Swing). Your book should be consistent in the time frame of the material presented, so learning as you are is probably okay, but it's unfortunate that you have to learn the AWT classes that have been built upon - extended and improved - by the Swing classes. When you are able to begin using Swing classes, it is recommended to not mix AWT components with Swing components in the same class or program.

    Good luck and keep coding!

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    einar123 (August 6th, 2013)

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    Default Re: How to build more actions in exicting code. A continum problem.

    Hey guys. I'm just not cutting it. I can not build another action, action2. I've tried viping it out, then I get red dots all over the place. Can you give me any ideas?

    I'm trying to build another button, ''-'' button onto + action in a ''calculating machine''


     
    import java.applet.Applet;
    import java.awt.Button;
    import java.awt.Event;
    import java.awt.Label;
    import java.awt.TextField;
     
     
     
    	public class Reiknivel extends Applet 
    	{
    		/**
    		 * 
    		 */
    		private static final long serialVersionUID = 1L;
    		TextField t1, t2, tsvar;
    		Button bplus; Button bminus;
    		Label a1, a2, b3;
    		Double D1, D2;
    		double d1, d2, dsvar;
     
    		 public void init()
    		{
    			t1 = new TextField(3);
    			t2 = new TextField(3);
    			tsvar = new TextField(15);
    			bplus = new Button("+");
    			bminus = new Button("-");
    			a1 = new Label ("Tala 1");
    			a2 = new Label ("Tala 2");
    			b3 = new Label ("Samanlagt");
     
    			this.add(a1); 
    			this.add(t1);
    			this.add(bplus);
    			this.add(bminus);
    			this.add(a2);
    			this.add(t2);
    			this.add(b3);
    			this.add(tsvar);
    		}
     
    		public boolean action(Event e,Object o)
    		{
    			if (e.target == bplus)
    			{
     
    			D1 = new Double(t1.getText());
    			d1 = D1.doubleValue();
    			D2 = new Double(t2.getText());
    			d2 = D2.doubleValue();
    			dsvar = d1 + d2;
    			tsvar.setText("Summan er: " + dsvar);
    			return true;
    			}
    			return false;
     
    		}
    		public boolean action2(Event e,Object o)
    		{
    			if (e.target == bminus)
    			{
     
    			D1 = new Double(t1.getText());
    			d1 = D1.doubleValue();
    			D2 = new Double(t2.getText());
    			d2 = D2.doubleValue();
    			dsvar = d1 - d2;
    			tsvar.setText("Summan er: " + dsvar);
    			return true;
    		    }
    			return false;
    	}
    	}

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    Default Re: How to build more actions in exicting code. A continum problem.

    I suggest you do this:
    	public boolean action(Event e,Object o)
    	{
    		if (e.target == bplus)
    		{
    			D1 = new Double(t1.getText());
    			d1 = D1.doubleValue();
    			D2 = new Double(t2.getText());
    			d2 = D2.doubleValue();
    			dsvar = d1 + d2;
    			tsvar.setText("Summan er: " + dsvar);
    			return true;
    		}
    		else if (e.target == bminus)
    		{
    			D1 = new Double(t1.getText());
    			d1 = D1.doubleValue();
    			D2 = new Double(t2.getText());
    			d2 = D2.doubleValue();
    			dsvar = d1 - d2;
    			tsvar.setText("Summan er: " + dsvar);
    			return true;
    		}
    		return false;
     
    	}

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    einar123 (August 6th, 2013)

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    Default Re: How to build more actions in exicting code. A continum problem.

    Master GregBrannon. In Iceland it's about twelve, it's sleeping time. I will sleep well, because of your contribution (hahah). Problem solved!

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    Default Re: How to build more actions in exicting code. A continum problem.

    Glad to help, and sleep well!

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