Q: how to declare null value to integer in android I want to know how I should declare a Integer with Null Value in Android.
Here is my code:
btnload.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            String getDate, getEpayee, getEcategory;
            int getEamt;
            getDate= "";

            getEamt="";  //This Eamt variable is of integer type and
                                       //this gives me a error.

            getEpayee ="";
            getEcategory="";


A: int is a primitive type in Java; hence you cannot set it to null (it is not an object).
if getEamt is an int, you cannot initialize it to a String. If you really want to set an integer to null you need to use the Integer class.

A: If you want to use some kind of "default" or initialization value with the int type, you might consider starting to count at 1 and interpret 0 or a negative int as the default value.

A: You have probably miss understand what null is. 
In the example you have posted you use empty string "". So you can initialize String instances to avoid NullPointerException. In case you do not initialize (assign at declaration) any value you have null value by default for Object types.
String message; is equal to String message = null;
What your are doing by String message = "" is that you set a reference to empty string. 

The null is applicable only for Object types not primitive ones. How ever each primitive has a wrapper class that allow null. 
You can do this 
Integer value = null;
You can not do this 
int value = null;
In general you should avoid the null. Usage of primitive assure that you will never pass a null. 
As in your code the declaration are local you should declare them just before usage with valid value instead of create a section of initialization and then a block of usage. 
btnload.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
           conductPaymentTransaction()
        }

private void conductPaymentTransaction() 
{

 Date          date = getDate();
 EPayee        paye = getEPayee()
 ECategory category = getECategory();
 int        ammount = getAmmount();

 //...

}

Note: you should not store your data structure in form of plain string. 
