Their are two methods you can use to pass an integer. One is as shown below.
A.class
Intent myIntent = new Intent(A.this, B.class);
myIntent.putExtra("intVariableName", intValue);
startActivity(myIntent);
B.class
Intent intent = getIntent();
int intValue = intent.getIntExtra("intVariableName", 0);
The other method converts the integer to a string and uses the following code.
A.class
Intent intent = new Intent(A.this, B.class);
Bundle extras = new Bundle();
extras.putString("StringVariableName", intValue + "");
intent.putExtras(extras);
startActivity(intent);
The code above will pass your integer value as a string to class B. On class B, get the string value and convert again as an integer as shown below.
B.class
Bundle extras = getIntent().getExtras();
String stringVariableName = extras.getString("StringVariableName");
int intVariableName = Integer.parseInt(stringVariableName);