content: package com.alexjlockwood.example.delight;
  
  import android.os.Bundle;
  import android.support.v7.app.AppCompatActivity;
  import android.view.View;
  import android.widget.ImageView;
  
  import butterknife.BindView;
  import butterknife.ButterKnife;
  import butterknife.OnClick;
  
  public class FingerprintActivity extends AppCompatActivity {
    private static final int[] STATE_SET_ON =
        {R.attr.state_on, -R.attr.state_off, -R.attr.state_error};
    private static final int[] STATE_SET_OFF =
        {-R.attr.state_on, R.attr.state_off, -R.attr.state_error};
    private static final int[] STATE_SET_ERROR =
        {-R.attr.state_on, -R.attr.state_off, R.attr.state_error};
  
    @BindView(R.id.icon) ImageView iconView;
    @BindView(R.id.on) View onButton;
    @BindView(R.id.off) View offButton;
    @BindView(R.id.error) View errorButton;
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_fingerprint);
      ButterKnife.bind(this);
    }
  
    @OnClick(R.id.on)
    void setFingerprintOn() {
      onButton.setEnabled(false);
      offButton.setEnabled(true);
      errorButton.setEnabled(true);
      iconView.setImageState(STATE_SET_ON, true);
    }
  
    @OnClick(R.id.off)
    void setFingerprintOff() {
      onButton.setEnabled(true);
      offButton.setEnabled(false);
      errorButton.setEnabled(false);
      iconView.setImageState(STATE_SET_OFF, true);
    }
  
    @OnClick(R.id.error)
    void setFingerprintError() {
      onButton.setEnabled(true);
      offButton.setEnabled(false);
      errorButton.setEnabled(false);
      iconView.setImageState(STATE_SET_ERROR, true);
    }
  }
  