Trying to 'simulate' an array of strings

Question

In pseudo-code what I would like to do is this:
Array[x][3]
Array[1][1] = "First"
Array[1][2] = "Data1"
Array[1][3] = true
Array[2][1] = "Second"
Array[2][2] = "Data2"
Array[2][3] = false
counter = 1
while(counter < 3) {
print Array[counter][1]
counter++
In Java-think I created a class of data, and wanted to create a series of elements (array) of this class. But, suprise, my code snippit below doesn't work....
class DataSaved {
String InputName;
String InputValue;
boolean IsHidden;
public class test {
public static void main(String [] args) {
DataSaved dataum;
int counter = 0;
dataum = (DataSaved) DataSaved.firstElement();
dataum.addElement("first","1data",true);
dataum.addElement("second","2data",true);
dataum.addElement("third","3data",true);
dataum.addElement("xxxfirst","4data",true);
dataum.addElement("fxxirst","5data",true);
dataum.addElement("sixfirst","6data",true);
dataum.addElement("7first","7data",true);
dataum.addElement("8first","8data",true);
dataum.addElement("9first","9data",true);
// move to the top element
datum.firstElement();
while (counter < 6 ){
System.out.println(dataum.nextElement());
counter++;
So....what am I not understanding, and how can I make this snippit work?

Answer 1

Great, now your DataSaved class is correct.
The next step is how to deal with arrays.
Suppose you have an array of Strings. Here's how it looks like:
String[] myArray;Before you can use it, you have to actually occupy the space it needs. (Arrays are objects in Java, so basically, but sloppily speaking, you have to instantiate an "array class"):
myArray = new String[15];The length of the arrays in Java is constant. You have to tell the length during construction time, and you won't be able to change it later.
Also, if you create an array as above, each of the elements will contain null (were it an array of primitive types, it would contain the appropriate version of zero for that primitive type). Therefore, you have to load the elements one by one:
myArray[0] = new String("first string");
myArray[1] = new String("second string");
myArray[14] = new String("last string");As you see, indexing starts with zero. I also have to note, that "new String(...)" is an unnecessary and in most cases poor programming technic, the string constants would do in this case (but not if the array is not an array of strings but array of some kind of objects).
Another note. It's usually a bad programming technic to reach the fields of another class. Sometimes we do, but only when we have good reason. It's better if you provide setXXX and getXXX methods, and let your fields to have private access:
class DataSaved {
   // your current code appears here
   public void setInputName(String name) {
      InputName = name;
   public String getInputName() {
      return InputName;
}Now, your cycle which retrieves the values should look something like this:
for (int cntr=0;  cntr<myArray.length;  cntr++) {
   System.out.println(myArray[cntr].getInputName());
}That myArray.length is an attribute of the arrays, which tells you the length of the array. Now, if you have to change the length later, you don't have to scrutinize your code, since the "magic number" appears in the code exactly once.
You may read about the arrays and how they're handled in Java here:
http://java.sun.com/docs/books/tutorial/java/data/arrays.html
That ArrayList is another story; if you have succeeded with your array, come back and ask. "Preview": ArrayList is a way how to deal with arrays which might be expanded and shrunk as needed.
You also might consider reading the tutorial about the collections (perhaps in a later time):
http://java.sun.com/docs/books/tutorial/collections/index.html