访问另一个类中的数组？

Question

I am working on a program that will add randomly generated numbers to an array. I need to be able to track how many numbers are generated before a duplicate number is generated. I have an interface and and ArrayIntLog class. the class holds an int[].

I get an error before I run my program that says "array required, ArrayIntLog found. If i understand what i have done right, the ArrayIntLog is storing input into the array log, but I'm not sure how to access that array from my TestLuck Class? I've tried using the name myLog[index] and just log[index] but but those give me errors as well.

Here is my TestLuck class:

package arrayintlog;

import java.util.Random;

public class TestLuck 
{

    public static void main(String[] args)
    {
        int cycles = 0;
        String name = "myLog";
        int min = 1;
        int max = 10000;
        int duplicateCheck;

        Random rand = new Random();
        int random = rand.nextInt(max - min + 1) + min;

        ArrayIntLog newLog = new ArrayIntLog(name);

        for (int index = 0; index < newLog.size(); index++)
        {
            newLog.insert(random);
            for(int index2 = 0; index2 < newLog.size(); index2++)
            {
                if (newLog[index].contains(newLog[index2]))
                {
                    System.out.println("You had to generate " + index + "numbers get a match");
                }
            }
        }

    }
}

Here is my ArrayIntLog class:

package arrayintlog;


public class ArrayIntLog implements IntLogInterface
{
    protected String name; //name of the IntLog
    protected int[] log; //array that holds the integers
    protected int lastIndex = -1;

    //==========================Constructor=====================================
    public ArrayIntLog(String name, int maxSize)
    {
        log = new int[maxSize];
        this.name = name;
    }

    //==========================Constructor=====================================
    public ArrayIntLog(String name)
    {
        log = new int[100];
        this.name = name;
    }

    //===========================Insert=========================================
    public void insert(int element) 
    {
        lastIndex++;
        log[lastIndex] = element;
    }

    //===========================isFull=========================================
    public boolean isFull() 
    {
        if(lastIndex == (log.length - 1))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    //============================Size==========================================
    public int size() 
    {
        return lastIndex + 1;
    }

    //===========================Contains=======================================
    public boolean contains(int element) 
    {
        int location = 0;
        while (location <= lastIndex)
        {
            if (element == (log[location]))
            {
                return true;
            }
            else
            {
                location++;
            }
        }
        return false;
    }

    /*=============================Clear========================================
    public void clear() 
    {
        for (int index = 0; index <= lastIndex; index++)
        {
            log[index] = null;
        }
        lastIndex = -1;
    }*/

    //=============================getName======================================
    public String getName() 
    {
        return name;
    }

    public String toString()
    {
        String logString = "Log " + name +"/n/n";

        for (int index = 0; index <= lastIndex; index++)
        {
            logString = logString + (index+1) + ". " +
                    log[index] + "/n";
        }
        return logString;
    }
}

Here is my IntLogInterface:

package arrayintlog;


public interface IntLogInterface 
{
    void insert(int element);
    //precondition: IntLog is not full
    //places element into the log

    boolean isFull();
    //returns true if the IntLog is full

    int size();
    //returns the number of elements in this IntLg

    boolean contains(int element);
    //return true if the IntLog contatains an element

    //void clear();
    //makes this IntLog empty

    String getName();
    //returns the name of this IntLog

    String toString();
    //returns a formatted string representing this IntLog 
}

Answer 1

If you need to access a non public variable of other class you better call the getter method of that variable.

Add this in your ArrayIntLog class:-

public int get(int index) {
        return log[index];
    }

And change the if condition to the below in your main method:-

if (newLog.get(index) == (newLog.get(index2)))
                {
                    System.out.println("You had to generate " + index + "numbers get a match");
                }

Answer 2

I didn't compile your code, but I think the error is in the line : if (newLog[index].contains(newLog[index2])) You've defined the object of class ArrayIntLog like this:

ArrayIntLog newLog = new ArrayIntLog(name);

But then you're trying to access it by calling : newLog[index] its illegal in Java. You might want to define an additional method in class ArrayIntLog + in the interface, something like this:

public class ArrayIntLog {

  ///...... the rest of the code:

  public int get(int index) {
    // you might want to check bound here as well, its your decision...
    return log[index];
  } 
}

This would give you an acess to the array. BTW, even in this case, it would be an error, because you can't do something like if (newLog.get(index).contains(newLog.(index2))) . I assume you meant this: if (newLog.contains(newLog[index2])) or maybe : if (newLog.get(index) == newLog[index2])) , I didn't check the logic of the code.

BTW, just an advice, java compiler produces pretty good error messages, you should even have an exact line of code where the compile fails to do its job. So it really worth to reading these compilation errors and trying to understand them.

Hope this helps

Answer 3

To access a contents of the array 'log' from other object, the 'ArrayIntLog' class must have a public method which provide access to the aray 'log'.

For example:

Add following code into the 'ArrayIntLog' class, and add "int getData(int index);" into the interface IntLogInterface.

public getData(int index)
{
    return log(index);
}

Then you can get data from the array of newLog object which is an instance of 'ArrayIntLog' class as follows. This example accesses third element of the array.

  thirdDataInArray = newlog.getData(3);