Intent intent = new Intent(context, ActivityB.class);
intent.putExtra("my_value", 2); //2 is the value you want to pass
startActivity(intent);

int variable = getIntent().getIntExtra("my_value", 0);//0 is the default value if the getintExtra doesn't find the "my_value"

Intent intent = new Intent(ActivityA.this,
ActivityB.class);
intent.putExtra("myInt", myInt);

getIntent().getIntExtra("myInt");