A method call question.

I am trying to check if leg1 is a positive integer, but I method call checkleg, and perform my if statement, but it will not return a 'valid = true' to my public static main. It is always false. please help!
* TriangleTest.java
* Created on October 3, 2007, 4:10 PM
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
package triangletest;
* @author Nate
import java.util.Scanner;
public class TriangleTest {
    /** Creates a new instance of TriangleTest */
    public TriangleTest() {
     * @param args the command line arguments
    public static void main(String[] args) {
        // TODO code application logic here
     System.out.println ("**Triangle Validation Tool**");
     int leg1 = 0;
     int leg2 = 0;
     int leg3 = 0;
     int sumOfLegs;
     int count = 0;
     Boolean validIs = false;
     Boolean valid = false;
     Scanner input = new Scanner (System.in);
        System.out.println("Please enter the length of leg #1:");
        leg1 = input.nextInt();
        checkleg (leg1);
        System.out.println(valid);
        System.out.println("Please enter the length of leg #2:");
        leg2 = input.nextInt();
        System.out.println("Please enter the length of leg #3:");
        leg3 = input.nextInt();
        sumOfLegs = leg1+leg2+leg3;
        if (sumOfLegs != 180)
            System.out.println("Sorry, legs of lengths " + leg1+ ", "
                    + leg2+ ", and " + leg3 + " do NOT form a triangle!");
        else
            System.out.println("Congrats!");
    public static Boolean checkleg (int leg1){
        Boolean valid = false;
        if (leg1>0){
        valid = true;
        System.out.println(valid);
    return valid;
    }}Thanks

Yippee!! the code tag button is back!!
Please see comments:
     Boolean validIs = false; // probably want to use "boolean" not "Boolean"
     Boolean valid = false; // ditto
     Scanner input = new Scanner (System.in);
        System.out.println("Please enter the length of leg #1:");
        leg1 = input.nextInt();
        checkleg (leg1); // see my previous post
        sumOfLegs = leg1+leg2+leg3;
        if (sumOfLegs != 180) // I hope you will correct this logic.
            System.out.println("Sorry, legs of lengths " + leg1+ ", "
                    + leg2+ ", and " + leg3 + " do NOT form a triangle!");
        else
            System.out.println("Congrats!");
    public static Boolean checkleg (int leg1){
        // note that while your local "valid" variable has the same name as the class "valid"
        // variable, they are both different variables and changing one will NOT change the other.
        Boolean valid = false;
        if (leg1>0){
        valid = true;
        System.out.println(valid);
    return valid;
    }}

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Method calling question

Can you call a nonstatic method from within a static method? If yes, how do I do it?

public class Test
public static void staticExample()
new Test().nonstaticExample();
public void nonStaticExample()
}

Question: Possible to assemble a method call within a program?

I am writing an interpreter for a school project. I would like to read all instructions into an array in the format PC: Instruction: arg1: arg2: destination:
My question is can I assemble from the Instruction name, for instance, "sqrt", a method call to public int[][] sqrt(int[][] varValue, int x, int d)? Is that even possible?
The challenge for me is, after having written all opcode instructions as methods, how do I call them after I read a text string? Is this even a good approach to algorithm design?
Thank you for your input.

Ebodee wrote:
My question is can I assemble from the Instruction name, for instance, "sqrt", a method call to public int[][] sqrt(int[][] varValue, int x, int d)? Is that even possible?Sure.
The challenge for me is, after having written all opcode instructions as methods, how do I call them after I read a text string? So you have an array of instructions, and you have a bunch of methods that implement the instructions, right?
(BTW, are the instructions really like sqrt? Because a more normal assignment would probably have you implement instructions like add, increment, store, etc.)
You could use reflection to get the methods, but that's kind of a hack and a cheat (because it diverges even further from an emulation -- it's harder to map meaningfully to hardware. (This is just my opinion of course.))
What I'd suggest is to create an Opcode interface, with a method like "void invoke(Object... args)". Then create an implementation of that for each opcode. Put objects of those methods into a Map<String, Opcode>. Then you can look them up by name.
Is this even a good approach to algorithm design?You're not really designing an algorithm here. It sounds like you're building an virtual processor of some kind. Quicksort is an algorithm. A simulation of a computer is an application.
Whether it's a good approach... it depends a lot on the assignment. At some point you're going to have to relinquish behavior from the emulation and let Java do some kind of bare computation. (You can't emulate everything; at some point lower-level software or hardware has to handle the semantics of what's going on.) The answer to your question depends on what level does the teacher want you to stay on. Can you write a sqrt function in Java and invoke it from your emulator, or do you have to write sqrt in the machine code of the emulator?

Question about method calling (Java 1.5.0_05)

Imagine for example the javax.swing.border.Border hierarchy.
I'm writing a BorderEditor for some gui builder, so I need a function that takes a Border instance and returns the Java code. Here is my first try:
1 protected String getJavaInitializationString() {
2     Border border = (Border)getValue();
3     if (border == null)
4         return "null";
5
6     return getCode(border);
7 }
8
9 private String getCode(BevelBorder border) {...}
10 private String getCode(EmptyBorder border) {...}
11 private String getCode(EtchedBorder border) {...}
12 private String getCode(LineBorder border) {...}
13
14 private String getCode(Border border) {
15     throw new IllegalArgumentException("Unknown border class " + border.getClass());
16 }This piece of code fails. Because no matter of what class is border in line 6, this call always ends in String getCode(Border border).
So I replaced line 6 with:
6     return getCode(border.getClass().cast(border));But with the same result. So, I try with the asSubClass() method:
6     return getCode(Border.class.asSubClass(border.getClass()).cast(border));And the same result again! Then i try putting a concrete instance of some border, say BevelBorder:
6     return getCode(BevelBorder.class.cast(border));Guess what! It worked! But this is like:
6     return getCode((BevelBorder)border);And I don't want that! I want dynamic cast and correct method calling.
After all tests, I give up and put the old trusty and nasty if..else if... else chain.
Too bad! I'm doing some thing wrong?
Thank in advance
Quique.-
PS: Sorry about my english! it's not very good! Escribo mejor en espa�ol!

Hi, your spanish is quite good!
getCode(...) returns the Java code for the given border.
So getCode(BevelBorder border) returns a Java string that is something like this "new BevelBorder()".
I want Java to resolve the method to call.
For example: A1, A2 and A3, extends A.
public void m(A1 a) {...}
public void m(A2 a) {...}
public void m(A3 a) {...}
public void m(A a) {...}
public void p() {
    A a = (A)getValue();
    // At this point 'a' could be instance of A1, A2 or A3.
    m(a); // I want this method call, to call the right method.
}This did not work. So, i've used instead of m(a):
    m(a.getClass().cast(a));Didn't work either. Then:
    m(A.class.asSubClass(a.getClass()).cast(a));No luck! But:
    m(A1.class.cast(a)); // idem m((A1)a);Woks for A1!
I don't know why m(A1.class.cast(a)) works and m(a.getClass().cast(a)) doesn't!
thanks for replying!
Quique

Closing an anonymous stream in method call

Will an anonymous stream in a method call be closed in the same manner an anonymous stream that is created in an object instantiation will be?
I know this will close the anonymous FileInputStream:
DataInputStream in =
new DataInputStream(new FileInputStream("filename.txt"));
/* ... code ... */
in.close();But will this?
MyPropertiesClass myPropertiesClass = new MyPropertiesClass();
myPropertiesClass.store(new FileOutputStream("file.txt"));MyPropertiesClass extends Properties, and uses its store().
I know the JavaDoc for Properties says:
"After the entries have been written, the output stream is flushed. The output stream remains open after this method returns."
My question is will the FileOutputStream("file.txt") be closed and garbage collected eventually after this method call because I don't have a reference to it? myPropertiesClass sticks around for a long time afterwards, will the FileOutputStream as well?
Thanks for any insight,
KJ

My question is will the FileOutputStream("file.txt") be closed and garbage collected eventually after this method call because I don't have a reference to it? > myPropertiesClass sticks around for a long time afterwards, will the FileOutputStream as well?Your only hope would be if FileOutputStream overrode finalize and closed the stream there -- but it doesn't (check the API -- finalize isn't overridden). I doubt if Properties retains a reference to the OutputStream you pass to store -- why would it need to? In any case, the bottom line is that output stream isn't being closed until your process exits.
Why not bite the bullet and rewrite that line of code so that you can explicitly close the stream?
OutputStream out = new FileOutputStream("file.txt");
try {
myPropertiesClass.store(out);
} finally {
out.close();
}It's not one line, but who cares? You could wrap it up in a short utility method:
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Method called reverse that switches complex number coordinates.

I have written a class called "Complex" and there are no errors in the program.
What I am confused about is how to answer an assigned question. The question
is this: "Write a method called reverse which will return a new complex number
with the coordinates reversed. That is, if the complex number which invokes
the method has coordinates (a,b), then the method should return a new complex
value with coordinates (b, a)."
I will include my code for the class here (I'm using the NetBeans IDE):
* To change this template, choose Tools | Templates
* and open the template in the editor.
package tutorial8;
* @author Aleks
public class Complex
    private int I; // Real Part
    private int J; // Imaginary Part
    public Complex(int I, int J)
    setComplex(I, J);
public int getI()
    return I;
public int getJ()
    return J;
public void setComplex(int I, int J)
this.I=I;
this.J=J;
if (I==J)
System.out.println("true");
else
System.out.println("false");
}thanks.

Your right it compiles without errors but it says it's missing a main method.
This main method thing is driving me insane. Some of my classes work such as the following
one:
* To change this template, choose Tools | Templates
* and open the template in the editor.
package tutorial7;
* @author Aleks
import java.util.Scanner;
public class Shortcalculation
    public static void main(String[] args)
        Scanner keyboard = new Scanner(System.in);
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}But I don't see why THIS one shouldn't. I try to include a "public static void main(string[] args)"
in the class complex but it says it's an illegal start of the expression. Maybe it depends on
where in the class I put it. I'm only practicing writing classes for 3-4 weeks now because I've read
a lot of the book. Too bad my memory is kind of bad. Ok, I have changed the class for this
question, I have added a reverse method. I did it without a return statement.
* To change this template, choose Tools | Templates
* and open the template in the editor.
package tutorial8;
* @author Aleks
public class Complex {
    private int I; // Real Part
    private int J; // Imaginary Part
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public void setComplex(int I, int J)
this.I=I;
this.J=J;
if (I==J)
System.out.println("true");
else
System.out.println("false");
public void reverse()
this.I=J;
this.J=I;
}sorry for the long post.

Best practice for method calling on objects within a collection.

Hi guys
As you may be aware, based on my other thread here. I'm designing a card game in Java. I was hoping for some advice on the best practise on how methods should be called on a custom Object contained within a custom Collection.
I have an instance variable for the Deck class as follows: List<Card> deckWhen creating an instance of the class I use deck = new ArrayList<Card>();So I have a Deck which only holds Card objects. My question is, for the Card methods, should I call them on the Card objects after 'getting' the Cards from the Deck or should I write methods within the Deck class which handles this method calling. Code explanation is as follows:
Deck standardDeck = new Deck();I want to retrieve the suit value of a card within the deck. Is this the best way to do it this way:
standardDeck.getCardAt(50).getSuit();
//getCardAt is a method within the Deck class, getSuit() is a method within the Card classor this way:
standardDeck.getSuitForCardAt(50);
//getSuitForCardAt() is a method within the Deck class. This method calls the getSuit() method within its method body.Cheers for any help guys.
Edited by: Faz_86 on Jul 10, 2010 9:53 AM

Hey Saish
Thanks for the response.
My Card class does indeed override hashCode(), equals() and toString().
The reason I am asking a card from the deck for its Suit is simply because of the rules of the game being played. The game I made is a 'Card Shredding' game where a player attempts to remove as many cards from their hand during each turn. The first to remove all their cards is the winner.
When the game starts, two decks are created. A standard 52 card deck and an empty deck. Then 8 cards are dealt to each player and one card is dealt into the empty deck. The suit and value of the card on the empty deck called the 'shredding deck' dictates which moves are valid during each turn; The played card must match the Suit or the Value of the current card on the 'shredding deck'
For example:
Card on the empty deck = 8 of Spades
The only card from a players hand which can be removed are any Spade or an Eight of any suit.
Going back to the Deck.getSuitOfCardAtIndex(int index) , this method is needed because both the AI player and human player need to have the ability to take a look at the cards which have been added to the 'shredding deck'. Again this is because of the rules of the game. Therefore I need a method to take a look at the Suit and Value for any card in the 'shredding deck'.
Taking all this into account, so far I have the following in my Deck class. Please comment on my design so far. As you can see I've tried to follow the Law Of Demter by creating many little wrapper methods. I understand totally wh getters and setters are bad but I cannot come up with a design solution to achieve what I need to based on the rules of the game without users getters. - Any tips on this would be great.
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Preventing hang on a method call in doGet ()

Hi,
I have the following problem.
Inside the doGet() method, I have a method call X which may take a long time or hand, what it does is do some calculations and return a object Obj. Then I can send this Obj back to client.
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Can anybody help me with some sample code or suggestion?
Any input will be appreciated.

Thanks, @Sujoy.
According to your suggestion, each expensive method will take AT LEAST the specified wait miliseconds to finish.
My solution was to start a timer thread before call the method, after the X number of miliseconds, the thread will check the return object from the method. but the problem is the thread has no way to access to the local varialbe inside the method. If you make the variable outside the doGet, which is an instance variable, every request thread will be capable of changing it, which is not acceptable.
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Method calls in switch and for statements

I have 2 questions concerning method calls in switch and for statements. Consider these two chunks of code:
1)
     switch (foo.getIntegerValue()){
          case 1:
          case 2:
     }My question is, is getIntegerValue() being called for every case statement (since it has to compare with each case) or is the method called only once?
2)
for (Foo bla : xyz.compileFoos()) {
}Is compileFoos called once or on every iteration?
I assume it gets called only once but I would like to be sure. The reason I ask is of course to avoid multiple method calls.
any help is appreciated

sdb2 wrote:
I have 2 questions concerning method calls in switch and for statements. Consider these two chunks of code:
1)
     switch (foo.getIntegerValue()){
          case 1:
          case 2:
     }My question is, is getIntegerValue() being called for every case statement (since it has to compare with each case) or is the method called only once?
     Once, and the value returned compared to each "case" in turn.
2)
for (Foo bla : xyz.compileFoos()) {
}Is compileFoos called once or on every iteration?
I assume it gets called only once but I would like to be sure. The reason I ask is of course to avoid multiple method calls.
any help is appreciatedAlso once, and the returned list/set/array is iterated over.

Display which method called the method (gives you a headache doesn't it)

Hi,
This question might sound a little weird, so maybe read it twice:
I would like to see which method called the method.
public void test1()
   test2();
public void test2()
   System.out.println(....);
The program output should be, test1 or classname.test1 or something like that. Is that possible?
Thanx in advance, Yvo van Beek

This should give you an idea: public static void main (String args[]) {
      wereAreWe();
      caller2();
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      catch (Exception ex) {
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I am wondering if the exported methods in app module are reliable. That is, when the method calls to the exported methods in AM fails for any reason, it will keep retrying until the method call succeeds. Also the marshalled method invocation packet is guaranteed to be received by the callee.

sdb2 wrote:
I have 2 questions concerning method calls in switch and for statements. Consider these two chunks of code:
1)
     switch (foo.getIntegerValue()){
          case 1:
          case 2:
     }My question is, is getIntegerValue() being called for every case statement (since it has to compare with each case) or is the method called only once?
     Once, and the value returned compared to each "case" in turn.
2)
for (Foo bla : xyz.compileFoos()) {
}Is compileFoos called once or on every iteration?
I assume it gets called only once but I would like to be sure. The reason I ask is of course to avoid multiple method calls.
any help is appreciatedAlso once, and the returned list/set/array is iterated over.

What's the chain of methods called for painting components?

Hi, I'm trying to find out at what point components are painted within a container, as in what methods are being called for that component to be rendered to the graphics context.
I've tried watching for calls going to paint, paintAll and paintComponents, but if a component has been added to a container it seems that even if I override all of those methods of the container the components that have been added still get displayed.
So I suppose I have two questions:
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* - What are the purpose of paintAll & paintComponents, I can't find anything that actually uses these calls.
Thanks in advance,
L

Well it seems that the paint method of the component is being called from sun.awt.RepaintArea.paint(...) which itself is being kicked off from handling an event that's been thrown.
That's clearer now....but has anyone seen when paintAll, paintComponents or the printXXX counterparts have actually been called by a part Sun's code? I can see how they (Sun) would advocate a practice lke this, but it would seem kinda lame for them to suggest it and then for them not to use it themselves.....that's why I think there's probably something in the JRE that does call these methods at sometime....can anyone cast some light on this?

Please help on how to use variables inside a method call

Hello guys,
How's it goin?
Pardon me if you find my question silly, but I am relatively
new in ActionScript 2.0 programming.
I have here a simple problem. It seems I can't use a variable
inside a method call of an object. Here's the code. Please note of
the authParams string variable below.
import AkamaiConnection;
import mx.services.WebService;
var GeneratedToken:String;
var authParams:String;
// Create a Web Service object
var TokGenService:WebService = new WebService("
http://webservice.asmx?wsdl");
// Call the web service method
var myToken:Object = TokGenService.GenerateToken();
// Create an AkamaiConnection object
var connection:AkamaiConnection = new AkamaiConnection();
connection.addEventListener("onConnect", this);
connection.addEventListener("onError", this);
// If you get a result from the web service, save the result
in a variable
myToken.onResult = function(result)
// If you get a result from the web service, save the result
in a variable
myToken.onResult = function(result)
GeneratedToken = result;
authParams = GeneratedToken +
"&aifp=v001&slist=37414/test/Streaming/";
//Call the Connect method of the AkamaiConnection class
connection.connect("cp37414.edgefcs.net/ondemand",true,true,5,true,false,"443","rtmpt",
authParams);
But then, if I use a hard-coded string value in lieu of the
variable, the method call works!
connection.connect("cp37414.edgefcs.net/ondemand",true,true,5,true,false,"443","rtmpt",
"testStringvalue");
I don't know what I'm missing or what I'm doing wrong... Can
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Flash CS3. Also, when I Trace output the variables, the values are
there. It just that they can't be read or recognize inside the
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The result param is a returned, “Decoded ActionScript
object version of the XML”. I am not exactly sure what that
means but I have had issues of returned XML values and their
datatype. When I did have these issues I had to cast or convert
into the desired datatype. Try one of the following, assuming the
problem is related to the code that you have bolded.
GeneratedToken = result.toString();
authParams = GeneratedToken +
"&aifp=v001&slist=37414/test/Streaming/";
Or
GeneratedToken = String(result);
authParams = GeneratedToken +
"&aifp=v001&slist=37414/test/Streaming/";
Or
GeneratedToken = result.toString();
authParams = String(GeneratedToken +
"&aifp=v001&slist=37414/test/Streaming/");

Native - Java Method Call problem - "Wrong Method ID..."

I am writing a 3d game engine using c++, with all the game logic code in Java, for the purpose of making the thing extendible, easily modifyable, etc...
I am using J2SE JDK 1.2.2.
Most things work fine (engine-wise), but i have a few questions about problems i am having getting the JNI to work correctly with calls to Java Methods.
1. If I use FindClass() to get a jclass reference to a named class, I get one number back. If I then instantiate this class, and then call GetObjectClass() with the instance, I get another number, **which doesnt appear to work for anything**. What is going on here? Can the JVM give different jclass numbers for the same class? Is GetObjectClass() supposed to work?
2. Is AllocObject() alright for instantiating Java objects? It does seem to allocate memory, and method calls work to the new object. I am aware that it doesn't call a constructor, but I like that, seeing as the initialization is handled through a different [network-synchronized] means.
3. Using a jclass retrieved using FindClass(), which I store in a global variable, I am able to call methods on an instance that I created in a certain function. I then make sure (?) that the GC can't reclaim the class or object memory by getting a NewGlobalReference to both of them [just to be safe]. However, in a later function, I am unable to call methods using my stored method IDs, ["Wrong Method ID....JVM has been asked to shut down this application in an unusual manner..."]. I am also unable to acquire new methodIDs, as the system returns 0xCCCCCCCC for all method ID queries. Obviously, attempting to use those bogus method IDs results in a JVM crash, in a segment called [2 deep in the untraceable depths of JVM.dll] from the JNI CallVoidMethodV() function. Why is this happening? Is the GC getting in there despite my best efforts? Is it illegal to cache methodIDs, jclass references or jobject references? aaarrggh! :)
Thanks
Chris Forbes
Lead Programmer
Sprocket Interactive
[email protected]

Hi Chris,
I hit the same sort of problem, when writing a JVMDI ( VM debugger hook ), in C++.
My question remained unanswered too
http://forum.java.sun.com/thread.jsp?forum=47&thread=461503&tstart=30&trange=30
I didn't try a call to NewGlobalRef, as you did... but it sounds like it could be what I was missing.
I've a couple of ideas, but nothing definite for you.
1) maybe there's more than one classloader, so that multiple copies of the class are loaded
2) ensure you're compiling your DLL with "quad-word" ( 8 byte ) alignment.
Otherwise all your JNI references will be misaligned !
Since the JNI reference maps to a C++ pointer, it's possible that you can't cache any JNI references.
That's my vague feeling on the subject.
As a workaround, you may have to keep requesting any JNI references, eg. jclass & jmethod's, as you need them.
regards,
Owen

Null reference method call behaving oddly

Hi all, and a very happy new year!!
My question concerns the null reference; simply, why does the following code chooses to call any other method than the Object version (try it out). No matter what type i choose to replace the current String version with... I have not paid much thought to this, but i would have guessed the null reference calls the Object version in such a situation.
If i leave only the Object method and comment out all others, the code compiles fine and calls the Object version at runtime - but in case there are sub class versions, those will be called. WHY?
(im running jre 1.4.1).
The code:
public class NullTest {
     public void method(Object o) {
          System.out.println("Object Version");
     public void method(String s) {
          System.out.println("String Version");
     public static void main(String args[]) {
NullTest nullTest = new NullTest();
          nullTest.method(null);
}

schapel, the question related specifically to
null, in a context where no runtime type can be
inferred. It wasn't about overloading in general.Yes, I understand that. But here is the rule from the JLS:
"If more than one method declaration is both accessible and applicable to a method invocation, it is necessary to choose one to provide the descriptor for the run-time method dispatch. The Java programming language uses the rule that the most specific method is chosen."
Note that it does not refer specifically to a null argument.
The question is "why is the most specific method called?" The reason is that there are only a few possibilities for this rule:
1. The least specific method should be called. In this case, overloaded methods with more specific types could not be called.
2. If there is more than one method, it is a compile time error. Again, this would cause overloading to be useless.
3. The most specific method is called. It is only with this rule that overloading works. That's why Java uses this rule.

A method call question.

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