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2 really easy questions

11 replies on 1 page. Most recent reply: Apr 13, 2003 9:01 PM by Greg

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Greg

Posts: 7
Nickname: nobel
Registered: Apr, 2003

2 really easy questions

Posted: Apr 12, 2003 6:07 PM

I am very poor when it comes to programming, but trying really hard to pass my exam, I have two quick questions I hope someone can answer for me please....

Implement the method sum that gives summation of the passed array. ie; the array has five elements 1,2,3,4,5, then 15 should be returned.

public int sum (int [] array)
{

}
________________________________________________________

and I have been trying to practice some code but keep getting errors.....

public class DebugTest3
{
public static void main (String args[])
{
One oneVar= new One();
int answer = oneVar.getResult(10);
System.out.println("Answer=" +answer);

public abstract class One()
{
public abstract void displayResult(int result);
public int getResult(int num)
{
return 2 * num;
}}

Anyone's help is greatly appreciated.....
Nobel...

Charles Bell

Posts: 519
Nickname: charles
Registered: Feb, 2002

Re: 2 really easy questions

Posted: Apr 12, 2003 6:54 PM

public class Summer{
    public static void main(String[] args){
        int[] firstFiveNumbers = {1, 2, 3, 4, 5};
        Summer summer = new Summer();
        System.out.println("The sum is: " + summer.sum(firstFiveNumbers));
    }
    
    public int sum(int[] array){
        int n = 0;
        for (int i = 0; i < array.length; i++){
            n = n + array[i];
        }
        return n;
    }
}

Greg

Posts: 7
Nickname: nobel
Registered: Apr, 2003

Re: 2 really easy questions

Posted: Apr 12, 2003 7:06 PM

Thank you very much, much apreciated, I don't want to seem pushy, but did my code for the 2nd question work????

Greg

Posts: 7
Nickname: nobel
Registered: Apr, 2003

Re: 2 really easy questions

Posted: Apr 12, 2003 7:10 PM

Summer summer = new Summer();

I don't understand this part of the code, could you please elaborate on it for me... Thank you very much

Charles Bell

Posts: 519
Nickname: charles
Registered: Feb, 2002

Re: 2 really easy questions

Posted: Apr 12, 2003 7:32 PM

You have to create an instance of the class in the main method so you can refer to a non-static method.

Greg

Posts: 7
Nickname: nobel
Registered: Apr, 2003

Re: 2 really easy questions

Posted: Apr 12, 2003 7:34 PM

okay. I see, thank you....

Any luck with the code regarding Debugtest3?

That would really help me out alot..

Thanks....

Charles Bell

Posts: 519
Nickname: charles
Registered: Feb, 2002

Re: 2 really easy questions

Posted: Apr 12, 2003 7:43 PM

Since the class One is abstract, you can not instantiate it.
But you can extend it and provide a non abstract or concrete implementation of the displayResult method.

public class DebugTest3 extends One{
    public static void main (String args[]){
        DebugTest3 oneVar= new DebugTest3();
        int answer = oneVar.getResult(10);
        oneVar.displayResult(answer);
    }
    
    public void displayResult(int result){
        System.out.println("Answer = " + String.valueOf(result));
    } 
    
}

Greg

Posts: 7
Nickname: nobel
Registered: Apr, 2003

Re: 2 really easy questions

Posted: Apr 12, 2003 7:52 PM

you really saved me...thank you very much Charles.....

Charles Bell

Posts: 519
Nickname: charles
Registered: Feb, 2002

Re: 2 really easy questions

Posted: Apr 12, 2003 7:56 PM

That's it for this old man for tonight.
Let me hear from you if there is anything else.

Charles
charbell@bellsouth.net

I've got a slew of java code samples from previous questions answered at:
http://www.quantumhyperspace.com/SourceBank/index.jsp

Its got an email feauture so you can email yourself anything you want.

Greg

Posts: 7
Nickname: nobel
Registered: Apr, 2003

Re: 2 really easy questions

Posted: Apr 12, 2003 8:07 PM

Sorry to bug you again, but I ran the code and got errors

C:\Java\DebugTest3.java:7: cannot resolve symbol
symbol : class one
location: class DebugTest3
public class DebugTest3 extends One{
^
C:\Java\DebugTest3.java:12: cannot resolve symbol
symbol : method getResult (int)
location: class DebugTest3
int answer = oneVar.getResult(10);
^
2 errors

Charles Bell

Posts: 519
Nickname: charles
Registered: Feb, 2002

Re: 2 really easy questions

Posted: Apr 13, 2003 1:17 PM

First compile the following:

public abstract class One {
    
    public abstract void displayResult(int result);
        
    public int getResult(int num){
        return 2 * num;
    }
}

Then, the other class which depends on the above.
Make sure they are in the same directory.

public class DebugTest3 extends One{
    public static void main (String args[]){
        DebugTest3 oneVar= new DebugTest3();
        int answer = oneVar.getResult(10);
        oneVar.displayResult(answer);
    }
    
    public void displayResult(int result){
        System.out.println("Answer = " + String.valueOf(result));
 
    }   
}

Greg

Posts: 7
Nickname: nobel
Registered: Apr, 2003

Re: 2 really easy questions

Posted: Apr 13, 2003 9:01 PM

Thank you very much Charles!!!!

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