Unfortunately Interactive Story has Stopped

it gives me an error and ı cant not run it.

package com.example.hakan.interactivestory.ui;

import android.content.Intent; import android.graphics.drawable.Drawable; import android.support.v4.content.ContextCompat; import android.support.v4.content.res.ResourcesCompat; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.widget.Button; import android.widget.ImageView; import android.widget.TextView; import android.app.Activity; import android.graphics.drawable.Drawable;

import com.example.hakan.interactivestory.R; import com.example.hakan.interactivestory.model.Story; import com.example.hakan.interactivestory.model.page;

public class StoryActivity extends Activity {

public static final String TAG = StoryActivity.class.getSimpleName();

private Story mStory = new Story();

private TextView mTextView;
private ImageView mImageView;
private Button mChoise1;
private Button mChoise2;
private String mName;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_story4);

    Intent intent = getIntent();
    mName = intent.getStringExtra(getString(R.string.key_name));

    if (mName == null){
        mName = "Friend";
    }
    Log.d(TAG, mName);

    mTextView = (TextView) findViewById(R.id.storyTextView);
    mImageView = (ImageView) findViewById(R.id.storyImageView);
    mChoise1 = (Button) findViewById(R.id.choiseButton1);
    mChoise2 = (Button) findViewById(R.id.choiseButton2);

}

private void loadPage(){
    page Page = mStory.getPage(0);

    Drawable drawable = ResourcesCompat.getDrawable(getResources(), Page.getImageId(), null);
    mImageView.setImageDrawable(drawable);

    String pageText = Page.getText();
    pageText = String.format(pageText,mName);
    mTextView.setText(Page.getText());

    mChoise1.setText(Page.getChoice1().getText());
    mChoise2.setText(Page.getChoice2().getText());
}

}

here is logCat

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1880) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) at android.app.ActivityThread.access$600(ActivityThread.java:123) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4424) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.NullPointerException at com.example.hakan.interactivestory.model.Story.<init>(Story.java:13) at com.example.hakan.interactivestory.ui.StoryActivity.<init>(StoryActivity.java:26) at java.lang.Class.newInstanceImpl(Native Method) at java.lang.Class.newInstance(Class.java:1319) at android.app.Instrumentation.newActivity(Instrumentation.java:1023) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1871) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)  at android.app.ActivityThread.access$600(ActivityThread.java:123)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)  at android.os.Handler.dispatchMessage(Handler.java:99)  at android.os.Looper.loop(Looper.java:137)  at android.app.ActivityThread.main(ActivityThread.java:4424)  at java.lang.reflect.Method.invokeNative(Native Method)  at java.lang.reflect.Method.invoke(Method.java:511)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)  at dalvik.system.NativeStart.main(Native Method)