Remove findViewById calls by using @Bind on widgets and fields.

Remove the click listeners by annotating methods with @OnClick and others.

    class MainActivity extends Activity {

      @Bind(R.id.user) EditText username;
      @Bind(R.id.pass) EditText password;

      @BindString(R.string.login_error)
      String loginErrorMessage;

      @OnClick(R.id.submit) void submit() {
        // TODO call server...
      }

      @Override public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.simple_activity);
        ButterKnife.bind(this);
        // TODO Use fields...
      }
    }

For Gradle dependency

compile 'com.jakewharton:butterknife:7.0.1'

NOTE: Don't forget to use ButterKnife.bind(this) in your Oncreate.