Java ME String array without size

Use ArrayList<String> when you don't know in advance the array size. What you are doing here is invalid (trying to access a null object).

Edit: as you can't use Vector and ArrayList, you'll have to roll you own implementation of dynamic array. You'll find one almost ready with some explanations on algolist.net. Simply replace the int storage by a String storage.

// Warning: not tested!
public class DynamicStringArray {
    private String[] storage;
    private int size;

    public DynamicArray() {
            storage = new String[10];
            size = 0;
    }

    public DynamicArray(int capacity) {
            storage = new String[capacity];
            size = 0;
    }

public void ensureCapacity(int minCapacity) {
    int capacity = storage.length;
    if (minCapacity > capacity) {
        int newCapacity = (capacity * 3) / 2 + 1;
        if (newCapacity < minCapacity)
            newCapacity = minCapacity;
        storage = Arrays.copyOf(storage, newCapacity);
    }
}

private void pack() {
    int capacity = storage.length;
    if (size <= capacity / 2) {
        int newCapacity = (size * 3) / 2 + 1;
        storage = Arrays.copyOf(storage, newCapacity);
    }
}

public void trim() {
    int newCapacity = size;
    storage = Arrays.copyOf(storage, newCapacity);
}

    //...
}

try

String[] names = new String[1];
names[0] = "Hello";

Use an ArrayList<String> if you don't know the size beforehand.

ArrayList<String> names = new ArrayList<String>();
names.add("hello");
names.add("another string");
...

looks like j2me has non-generic ArrayList that you could use like this.

ArrayList names = new ArrayList();
names.add("hello");
names.add("another string");
....

String name = (String) names.get(1);

How could i instantiate array as I dont know the the size limit

Sorry, that cannot be done. Arrays are of fixed size in Java, and you have to give the size when you create the array.

If you need a flexible buffer, consider using an ArrayList instead. That will grow as needed.

If you don't know the size limit (or more generally: almost always) you'll want to use a List instead of an array, because it's much more comfortable to handle.

List<String> names = new ArrayList<String>();
names.add("Hello");

The reason you're getting an exception (a NullPointerException) is that you only defined a variable to reference a String-array, but created no String array.

You'd have to initialize it like this:

String[] names = new String[10];

As you explained yo want to use it at J2ME there is no ArrayList provided for J2ME however there is an implementation here:

http://kickjava.com/src/j2me/util/ArrayList.java.htm

You can try it.

Also you should consider here too:

http://www1.j2mepolish.org/javadoc/j2me/de/enough/polish/util/ArrayList.html

As you are on J2ME and say you can't use arraylist I don't see you having any choice.

You need to choose a reasonable starting size for your array, watch the size, and if you need to add more objects than the size, copy it to a larger array.

With our constraints I cannot think of another way.

you can use with vector

Vector strings=new Vector();
strings.addElement("HELLO");
//then convert it to string array
String str[]=new String[strings.size()];
str[0]=(String)strings.get(0);

like this.. Hope this helpfull

String str[] = { "ABCde","xyZ","sdsdsdf"} ;

String str[][] = { {"ABC","abc"} ,
                {"pqr","qwerTY"}
              } ;