Android butter knife in a activity

Question

I am just trying to use butter knife in my activity. Added the latest jar and run the application. But Nothing is working. Here is my code. Whats wrong in this

@InjectView(R.id.buttonClick) Button buttonClick;
@InjectView(R.id.textField) TextView textField;

@OnClick(R.id.buttonClick) void sayHello(){
    textField.setText("Hello");
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ButterKnife.inject(this);
}