LayerView.java

package neocom.dealerbook.views;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.Transformation;
import android.widget.LinearLayout;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

import butterknife.Bind;
import butterknife.ButterKnife;
import butterknife.OnCheckedChanged;
import butterknife.OnClick;
import neocom.dealerbook.R;

/**
 * Created by wviana on 04/04/16.
 */
public class LayerView extends LinearLayout implements RadioGroup.OnCheckedChangeListener {

    public static final int DURATION_MILLIS = 250;
    @Bind(R.id.layer_options) LinearLayout layerOptions;
    @Bind(R.id.layer_name) TextView layerName;
    private boolean expanded = true;
    private LayerPropertiesChangeListener layerPropertiesChangeListener;
    @Bind(R.id.presenter_options) RadioGroup presenterSelector;

    public static class Builder {
        private String layerName;
        private boolean expanded;
        private LayerPropertiesChangeListener propertiesChangeListener;
        private List<Integer> presenterIcons = new ArrayList<>();
        private Context context;

        public Builder(Context context){
            this.context = context;
            expanded = false;
        }

        public Builder layerName(String name){
            this.layerName = name;
            return this;
        }

        public Builder addPresenterIcon(int icon){
            this.presenterIcons.add(icon);
            return this;
        }

        public Builder propertiesChangeListerner(LayerPropertiesChangeListener listener){
            this.propertiesChangeListener = listener;
            return this;
        }

        public LayerView build(){
            return new LayerView(this);
        }
    }

    private LayerView(Builder builder){
        this(builder.context);

        layerName.setText(builder.layerName);
        expanded = builder.expanded;
        layerPropertiesChangeListener = builder.propertiesChangeListener;

        for(int icon : builder.presenterIcons){
            addPresenter(icon);
        }

        updatePresenterSelectorBackground();

        if(presenterSelector.getChildCount() > 0 && presenterSelector.getCheckedRadioButtonId() == -1){
            presenterSelector.check(0);
        }
    }

    public LayerView(Context context) {
        super(context);

        LayoutInflater.from(context).inflate(R.layout.layer_view, this, true);
        ButterKnife.bind(this);

        presenterSelector.setOnCheckedChangeListener(this);
        setOrientation(VERTICAL);

    }

    @OnClick(R.id.layer_name)
    public void onLayerLabelClicked(){
        if (!expanded) {
            expand();
        } else {
            collapse();
        }
    }

    public void expand(){
        layerOptions.measure(LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        final int targetHeight = layerOptions.getMeasuredHeight();
        layerOptions.setVisibility(VISIBLE);
        layerOptions.requestLayout();

        Animation a = new Animation(){
            @Override
            protected void applyTransformation(float interpolatedTime, Transformation t) {
                layerOptions.getLayoutParams().height = (interpolatedTime == 1)
                        ? ViewGroup.LayoutParams.WRAP_CONTENT
                        : (int) (targetHeight * interpolatedTime);
                layerOptions.requestLayout();
            }

            @Override
            public boolean willChangeBounds() {
                return true;
            }
        };

        a.setDuration(DURATION_MILLIS);
        layerOptions.startAnimation(a);
        //layerOptions.animate().translationY(1f);
        expanded = !expanded;
    }

    public void collapse(){
        final int initialHeight = layerOptions.getMeasuredHeight();

        Animation a = new Animation(){
            @Override
            protected void applyTransformation(float interpolatedTime, Transformation t) {
                if (interpolatedTime == 1f) {
                    layerOptions.setVisibility(GONE);
                } else {
                    layerOptions.getLayoutParams().height = initialHeight - (int)(initialHeight * interpolatedTime);
                    layerOptions.requestLayout();
                }
            }

            @Override
            public boolean willChangeBounds() {
                return true;
            }
        };

        a.setDuration(DURATION_MILLIS);
        layerOptions.startAnimation(a);
        layerOptions.setVisibility(INVISIBLE);
        //layerOptions.animate().translationY(-100f);
        expanded = !expanded;
    }

    public void addPresenter(int icon){
        RadioButton presenter = new RadioButton(getContext());

        //Configura atributos padrão
        Drawable drawable = getResources().getDrawable(icon);
        presenter.setCompoundDrawables(drawable, null, null, null);

        presenterSelector.addView(presenter);

        presenter.measure(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        presenter.getLayoutParams().height = presenter.getMeasuredHeight();
        presenter.getLayoutParams().width = presenter.getMeasuredWidth();
        presenter.requestLayout();

        //updatePresenterSelectorBackground();
    }

    private void updatePresenterSelectorBackground(){
        int childCount = presenterSelector.getChildCount();
        for(int i = 0; i < childCount; i++){
            View rb = getChildAt(i);
            if(i == 0)
                rb.setBackgroundResource(R.drawable.presenter_radiobutton_left);
            else if (i == childCount - 1)
                rb.setBackgroundResource(R.drawable.presenter_radiobutton_right);
            else
                rb.setBackgroundResource(R.drawable.presenter_radiobutton_center);
        }
        presenterSelector.requestLayout();
    }

    @Override
    public void onCheckedChanged(RadioGroup radioGroup, int i) {
        if(layerPropertiesChangeListener != null){
            layerPropertiesChangeListener.onPresenterChange(i);
        }
    }

    @OnCheckedChanged(R.id.layer_switch)
    public void onChangeLayerEnabled(boolean isLayerOn){
        if(layerPropertiesChangeListener != null){
            layerPropertiesChangeListener.onLayerEnableChange(isLayerOn);
        }
    }

    //Presenter Change
    public interface LayerPropertiesChangeListener {
        void onPresenterChange(int presenterPosition);
        void onLayerEnableChange(boolean enabled);
    }

    public LayerPropertiesChangeListener getLayerPropertiesChangeListener() {
        return layerPropertiesChangeListener;
    }

    public void setLayerPropertiesChangeListener(LayerPropertiesChangeListener layerPropertiesChangeListener) {
        this.layerPropertiesChangeListener = layerPropertiesChangeListener;
    }
}

Strack

04-08 14:53:28.672 22193-22193/neocom.dealerbook E/AndroidRuntime: FATAL EXCEPTION: main
                                                                   Process: neocom.dealerbook, PID: 22193
                                                                   java.lang.RuntimeException: Unable to start activity ComponentInfo{neocom.dealerbook/neocom.dealerbook.activities.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setBackgroundResource(int)' on a null object reference
                                                                       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
                                                                       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
                                                                       at android.app.ActivityThread.access$800(ActivityThread.java:151)
                                                                       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
                                                                       at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                       at android.os.Looper.loop(Looper.java:135)
                                                                       at android.app.ActivityThread.main(ActivityThread.java:5254)
                                                                       at java.lang.reflect.Method.invoke(Native Method)
                                                                       at java.lang.reflect.Method.invoke(Method.java:372)
                                                                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
                                                                    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setBackgroundResource(int)' on a null object reference
                                                                       at neocom.dealerbook.views.LayerView.updatePresenterSelectorBackground(LayerView.java:185)
                                                                       at neocom.dealerbook.views.LayerView.<init>(LayerView.java:80)
                                                                       at neocom.dealerbook.views.LayerView.<init>(LayerView.java:28)
                                                                       at neocom.dealerbook.views.LayerView$Builder.build(LayerView.java:65)
                                                                       at neocom.dealerbook.models.layer.Layer.getView(Layer.java:216)
                                                                       at neocom.dealerbook.activities.MainActivity.onCreate(MainActivity.java:109)
                                                                       at android.app.Activity.performCreate(Activity.java:5990)
                                                                       at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
                                                                       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
                                                                       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
                                                                       at android.app.ActivityThread.access$800(ActivityThread.java:151) 
                                                                       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
                                                                       at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                       at android.os.Looper.loop(Looper.java:135) 
                                                                       at android.app.ActivityThread.main(ActivityThread.java:5254) 
                                                                       at java.lang.reflect.Method.invoke(Native Method) 
                                                                       at java.lang.reflect.Method.invoke(Method.java:372) 
                                                                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
                                                                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)