Questions on HW7-Spring07

Questions on HW7-Spring07

Question: This GUI will have a string input area where the user can type in a sequence of letters. The letters will define a MIDI sequence. Only the letters c,d,e,f,g,a, and b are allowed, presumed all in the third octave. Lowercase is an eighth note, uppercase is a quarter note. So cEdEgC would be c3 eighth, e3 quarter, d3 eighth, e3 quarter, g3 eighth, c3 quarter., from Homework 6 description.

This is what the hw says. I'm kind of confused about the musical part. How exactly are we supposed to get the various notes to play, eg. c3 in eighth, or c3 in quarter? Are we supposed to formulate these sounds or can we get them from somewhere online because all of these sounds are not in our mediasources folder. Could you please provide some clarification. Additionally, will this hw still be due March 30?

I don't believe you will be playing an individual note, but rather playing a SongNode containing one Phrase containing only one note. SongPhrase has some good examples of how to create Phrases. The notes are provided in JMC just import jm.JMC;. I don't really know how you can just play one SongNode though without using showFromMeOn(). The homework is still due Friday until further notice. Dawn Finney.
You have to do some modifications to the SongNode. Use the method Play.midi(phrase,false). The false is important here – without it, JMusic will quit after playing the sound. Play.midi will also play a score or a part. See http://jmusic.ci.qut.edu.au/jmDocumentation/jm/util/Play.html. To write out the MIDI to a file, you'll use Write.midi – see http://jmusic.ci.qut.edu.au/jmDocumentation/jm/util/Write.html. Mark Guzdial

Question: will the lowest homework grade be dropped when calculating the final grade?

No clue. Ask Joel or Prof. Guzdial. Dawn Finney.
No you will not be allowed to drop you lowest HW grade. We have now posted an extra credit assignment. Joel Uthe

Question: Are we making one node with the input sequence in it or a sequence of nodes, each with one note from the sequence? It doesn't make sense to me to be able to weave with only one node.

The input area takes in a sequence of letters to be used in the creation of one node, that one node can be added to the existing sequence of nodes. It sounds like you're making a linkedlist of nodes but using a GUI. Dawn Finney.
As Dawn says. Mark Guzdial

Question: We have the entire GUI set up nicely (appearance wise)... but I'm having a lot of trouble taking whatever string of letters that are input and then trying to convert those to individual notes... I believe that if I had a string to start out with, then I could convert it into notes... but I can't figure out how to take the input string and be able to save it with a certain name, so that I can then mess with it... in "RhythmTool", they use "num = Integer.parseInt(count.getText());" ... but what should we do if it is already a string?? Hopefully that made sense

I think your question is about how to actually go about dissecting the input String for the individual notes. Just calling getText() on the JTextField will return a String representation of whatever is in the box. Calling charAt(int index) will return the char at that position in the String. See Java documentation for charAt(int index). You can think of a String as an array of chars. You need to iterate through the String and take the appropriate action for each of the possible letter described in the homework. It is important to note that chars are primitives like ints so you can compare them using ==. For more fun with Strings see Java documentation on String. Dawn Finney.

Question: We named our input box as so: 'JTextField txt = new JTextField("Type Sequence Here");' ... then we tryed to access the "input" in order to make the node by typing this: 'String seq = new String(txt.getText());'... and this error popped up: 'local variable txt is accessed from within inner class; needs to be declared final' ... i have no idea how to gather the "input" and save it as a string... please help

The quick fix is to declare it final. Dawn Finney.
They haven't seen "final" yet, Dawn. Folks, check out the RhythmTool example. You need to declare the variables that you want to access within the inner class at the level of the instance. You can't access variables local to the method in the inner class. (We did talk about this in lecture, for the 50 people who were there.) Mark Guzdial
By the way, RhythmTool.java is your java-sources folder. Dawn Finney.

Question: Should the "MakeNode" button add the current sequence to the list, or just make it into a floating node? If the latter, does that mean the RepeatInSequence and WeaveInSequence should be enacted on the node you just made using the "MakeNode" command, or should they be enacted on the sequence currently in the input area?

MakeNode should create the node a floating node. RepeatInSequence and WeaveInSequence should use the floating node and make additions to the sequence of nodes. I really think there should be like an "AddToTheEndOfSequence" button. Dawn Finney.
Sounds like a fine one to create for extra credit. Mark Guzdial

Question: Professor Guzdial gave us a method that would turn the string into a phrase in class today. Does this method need to be inside our MidiTool or where would we add that method. I'm confused with this whole GUI thing and how it works.

Depends on the method. As for the GUI thing, study RhythmTools.java and ask your TA questions. I don't exactly have time to rehash what's been said in lecture and recitation. Dawn Finney.
It can go in your MIDItool. Mark Guzdial

Question: Can we modify song node to make it do what we want or are we stuck with the default thing?

Go for it. Prof. Guzdial already hinted that you could (maybe should) modify SongNode in the first question. The data structure should stay a linked list though. Dawn Finney.
Like Guru Dawn said. Mark Guzdial

Question: When we tried to implement the code prof Guzdial gave us today it kept telling us that Note was not a class. The specific lines were:

Note myNote = null;
if (c == 'A') myNote = new Note(JMC.A3, JMC.QN);

Is Note even a class? If so where is it located?

Note is located in the java JMC package. You need to import it. Check out NotePlay.java for more information. Dawn Finney.
You have had to do some MIDI/JMusic assignments, so I figured that you'd know about that. Mark Guzdial

Question: We're getting this error when we push our make node button. We're making our node by getting all the note values, putting them into a phrase, and then putting the phrase into a node. Any idea what's causing all this?

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at MidiTool$2.actionPerformed(MidiTool.java:124)
	at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at javax.swing.AbstractButton$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)
        ...lots more

Thanks

Something's null and you're trying to do stuff to it. That's all I can get from the stack trace. Dawn Finney.
My bet is that your original value for your "floating" node is null, and it's still null when you hit MakeNode. How could it still be null? Did you hit RETURN in the text field? Until you do, the action listener doesn't fire. Mark Guzdial

Question: Is there a way to turn a note into a sound?

Why would you need to do that? Dawn Finney.
By playing the MIDI? Mark Guzdial

Question: "WeaveInSequence weaves the currently made node into the sequence every-other node onto the end. "We're a bit confused about what this statement means. Should we be weaving in the node every 1 node, or every 2 nodes? I.e., if we have six nodes, A B C D E F, and we want to weave in G, would it result in A G B G C..... or A B G C D G....?

I'm pretty sure it's every 1 node. Dawn Finney.
Yes, please. Every other node. That is what the assignment says: "WeaveInSequence weaves the currently made node into the sequence every-other node onto the end." Mark Guzdial

Question: We're trying to make it so that, if there are no numbers typed into the text field for the RepeatInSequence button, it prints out a line telling you to type in a number. But we are having a lot of difficulty writing an if statement to print this. We keep getting:

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""
	at java.lang.NumberFormatException.forInputString(Unknown Source)
	at java.lang.Integer.parseInt(Unknown Source)
	at java.lang.Integer.parseInt(Unknown Source)

	at MidiTool$4.actionPerformed(MidiTool.java:140)
        ...etc...

Any ideas?

Are you trying to parse the empty String 'cause that'll probably give you an error. It's better to check whether the String is null or not first. If the String is null, then print the error statement. If it is not null, then parse it for numbers. Dawn Finney.

Alright, I've made that change, but it's still not working. Using

if (count.getText() == null)

(where count is the JTextField) doesn't seem to do anything; I've tried commenting the code various ways, and it seems that the String is never being equal to null, even if I don't type anything. Any ideas?

I'm thinking that you should probably do something like this:

final JTextField repeatInSequenceTextField = new JTextField(null,5);
//The following should be in the ActionListener
if(repeatInSequenceTextField.getText()==null){
  //Do stuff
}

I think the problem is that "" != null. So if the contents of your JTextField either defaults to "" or set to "", it's not equal to null! "" is actually a String with a length of 0. Thus another way to approach this would be to do

final JTextField repeatInSequenceTextField = new JTextField("",5);
//The following should be in the ActionListener
if (repeatInSequenceTextField.getText().length() == 0){
  //Do stuff
}

Dawn Finney.

Why not put in a default value in the text field that is a valid number? That's what we do in the RhythmTool. Mark Guzdial

Question: For the "Weave Node" button we are cunfused about what we actually weave the node with. Do we add the node to the end of the sequence and then add the sequence to the end of the node? Some clarification would be great. Also how do we play the node and/or sequence without using showFromMeOn? I mean how can we just get the stuff to play when we hit the button?

All answered before. Look above. Dawn Finney.

Question: I am having a problem with the weave and repeat buttons. When i use these buttons to weave in or repeat a new sequence, it just repeats or weaves in the original songnode. Im thinking my problem is that I do not have the buttons reading the txtfield and make a new songnode but when i tried to fix that it still weaves in the original song node. any ideas?

You probably didn't fix it completely. Dawn Finney.

Question: For the makeNode button: when trying to make a class that will handle making the input letters into notes to put into a phrase, I get an error 'illegal start of expression'. Here's my code:

makeNode.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent e) {
     public method buildPhrase (String str) {

...then my code

It's probably that word "method" in your method header. You need specify whether you are return an Object or nothing. Dawn Finney.

Okay I've tried 'class' 'String' 'Object' 'object' 'void' 'Phrase' instead of 'method'....nothing works

(Smacks face) Oh right. I should've seen this before. You can't define a method in a method. Dawn Finney.
You can for an anonymous inner class, which is what they're supposed to be doing. The word "method" shouldn't be there. Mark Guzdial

Question: in my interactions panel I typed the following after importing all the requisite stuff:

Note noteCLower = new Note(JMC.C3,JMC.EIGHTH_NOTE);
Phrase phr1=new Phrase();
phr1.addNote(noteCLower.copy());
Play play=new Play();
play.midi(phr1);

It plays the note, and then a separate panel pops up and says:

"The Interactions Window Terminated by a call to System.exit(0).
The Interactions window will now be restarted."

The reason I ask is that I am trying to use code like this in my program and I am getting the same termination message. Thanks

"Use the method Play.midi(phrase,false). The false is important here � without it, JMusic will quit after playing the sound," from the first question posted on this page. Read the questions and answers on this page before posting! I cannot stress this enough. Dawn Finney.

Question: I have tried two different ways to construct my phrase from the input, but when I test it, i get something totally different, for example if I put in ABC, I get a phrase that will have A, AB ,ABC it seems like I only need the last part but I dont know why it is showing all the other stuff before that.

You need to look at how you're constructing your phrase. It's probably a problem with looping 'cause it looks like your endpoint is gradually moving forward. Dawn Finney.

Question: Our code works fine if we use single notes as input, but if we try to input a string of notes longer than 2 (ie. ABC) for repeating or weaving we get an error: Exception in thread "AWT-EventQueue-0" java.lang.OutOfMemoryError: Java heap space... (along with a bunch of red messages). How can we fix that to compose more interesting things?

More than likely you have an infinite loop. Check your loops. Dawn Finney.

Question: I am trying to apply a method I made up to "root"(which is a SongNode) inside of an inner class. I am getting the following error message:

File: C:\cs1316\java-source-Fall06\java-source-Fall06\MidiTool.java  [line: 156]
Error: C:\cs1316\java-source-Fall06\java-source-Fall06\MidiTool.java:156: variable root might not have been initialized

what is happening?

You need to initialize root to something before using it. I can reproduce the error:

public class Text1{
  public static void main(String[]args){
    String s;
    s = s + "string";
  }
}

1 error found:
File: C:\Documents and Settings\Nwad\Text1.java  [line: 4]
Error: variable s might not have been initialized

Dawn Finney.

Repeating the things I said in class

My interpretation of the homework is that MakeNode does NOT change the sequence. Simply making a node should not also insert it. You want people to be able to hear the node that they entered, to see if they like it, BEFORE they insert it into the sequence. If you're doing that extra insertion (as some of the TA's have been telling people), then we won't take off points.
Here's how I imagine people using your tool:
- Enter "ABA" and hit return
- Click MakeNode then PlayNode. Hear "ABA"
- Type 5 and hit return.
- Click Repeat, then Play Sequence. I should hear: ABA,ABA,ABA,ABA,ABA.
- Type "ccc" and hit return.
- Click MakeNode and then PlayNode. I hear "ccc"
- Click Weave, then Play Sequence. I should hear: ABA,ccc,ABA,ccc,ABA,ccc,ABA,ccc,ABA (and maybe one more "ccc" depending on how you change your loop.)
What if you type Weave before Repeat? Your choice. You could do a Repeat (weaving into an empty list may be repeating that many times) or do nothing at all (since there are no nodes to weave into yet).
Mark Guzdial (Really me this time.:-)

Question: As we do what Guzdial says and we make the same nodes listed above, and we get to the weave button, we have an extra ccc, but it shows as the first node in the sequence. Is this ok, or should we fix it and what are suggestions on how to go about doing that.

It really shouldn't be the first node. The problem probably exists with your data structure. Dawn Finney.

Question: Do we have to turn in a pairs work sheet to the TA's again? and if so, where does it go?

You should only need to turn in another pairs worksheet if you made any changes to your pair assignment (ie. new pair, new addition to the pair,etc). Dawn Finney.

Question: how can you tell if your weave actually works. ive read through all the weave questions but i still dont really get how you can tell if your using the same sequenced node for everything. the effect of weave would look just like repeat.

See the powerpoint on weave. REMOVED story short: weave doesn't work like repeat. Dawn Finney.

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Homeworks-Spring 2007 last edited on 19 April 2007 at 10:45 pm by c-76-17-114-206.hsd1.ga.comcast.net