Java null pointer exception in Android application?

[AC Question]

java null pointer exception in android application

This is my main activity code:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.next);
EditText ed1;
ed1=(EditText) findViewById(R.id.editText);
final String Fname=ed1.getText().toString();
EditText ed2;
ed2=(EditText)findViewById(R.id.editText2);
final String Lname=ed2.getText().toString();
EditText ed3;
ed3=(EditText)findViewById(R.id.editText3);
final String Email=ed3.getText().toString();
EditText ed4;
ed4=(EditText)findViewById(R.id.editText4);
final String Password=ed4.getText().toString();
Button btn3;
btn3=(Button) findViewById(R.id.button3);
btn3.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
registerUser(Fname, Lname, Email,Password);
}
});
}
public Integer registerUser(String Firstname,String Lastname,String Email,String Password){
//log.debug("In Register...");
Toast.makeText(getApplicationContext(), "1", Toast.LENGTH_LONG).show();

XmlRpcClient client = getXmlRpcClient();
try {

HashMap<String, Object> fields = new HashMap<String, Object>();
fields.put("name",Firstname );
fields.put("display_name", Lastname);
fields.put("email", Email);
fields.put("password", Password);
Toast.makeText(getApplicationContext(), "3", Toast.LENGTH_LONG).show();
log.debug("Got the customer fields, rpc call to create customer");

List<Object> callParams = getCallParameters("res.partner", MainActivity.ActionType.CREATE);
callParams.add(fields);

Object result = client.execute("execute", callParams);

Integer customerId = (result != null) ? (Integer) result : null;

log.debug("Customer/Partner record created, Id = " + customerId);

//log.debug("About to create a user login in res_users");
registerUser(Firstname, Lastname, Email, Password);

return customerId;

} catch (Exception e) {
Toast.makeText(getApplicationContext(), "7"+e, Toast.LENGTH_LONG).show();
System.out.println("Excpt" + e);
Log.d(null,Log.getStackTraceString(new Exception()));
//log.error(e.getMessage());
//log.error(e.fillInStackTrace());
}
return 0;
}
When i click the register button it just throws the java null pointer exception though i have called the method and passed values for method inside the onclick listener but still am getting the same error