App keeps crashing...

09-19 22:17:54.262 19774-19774/com.teamtreehouse.interactivestory E/AndroidRuntime: FATAL EXCEPTION: main Process: com.teamtreehouse.interactivestory, PID: 19774 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.teamtreehouse.interactivestory/com.teamtreehouse.interactivestory.ui.StoryActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'com.teamtreehouse.interactivestory.model.Page com.teamtreehouse.interactivestory.model.Story.getPage(int)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6077) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'com.teamtreehouse.interactivestory.model.Page com.teamtreehouse.interactivestory.model.Story.getPage(int)' on a null object reference at com.teamtreehouse.interactivestory.ui.StoryActivity.loadPage(StoryActivity.java:51) at com.teamtreehouse.interactivestory.ui.StoryActivity.onCreate(StoryActivity.java:46) at android.app.Activity.performCreate(Activity.java:6662) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)  at android.app.ActivityThread.-wrap12(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:154)  at android.app.ActivityThread.main(ActivityThread.java:6077)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) 

package com.teamtreehouse.interactivestory.model;

import com.teamtreehouse.interactivestory.R;

/**

• Created by reevo on 9/18/2017. */

public class Story {

private Page[] pages;

public Story(){

    pages = new Page[7];

    pages[0] = new Page(R.drawable.page0,
                        R.string.page0,
                        new Choice(R.string.page0_choice1, 1),
                        new Choice(R.string.page0_choice2, 2));

    pages[1] = new Page(R.drawable.page1,
                        R.string.page1,
                        new Choice(R.string.page1_choice1, 3),
                        new Choice(R.string.page1_choice2, 4));

    pages[2] = new Page(R.drawable.page2,
                        R.string.page2,
                        new Choice(R.string.page2_choice1, 4),
                        new Choice(R.string.page2_choice2, 6));

    pages[3] = new Page(R.drawable.page3,
                        R.string.page3,
                        new Choice(R.string.page3_choice1, 4),
                        new Choice(R.string.page3_choice2, 5));

    pages[4] = new Page(R.drawable.page4,
                        R.string.page4,
                        new Choice(R.string.page4_choice1, 5),
                        new Choice(R.string.page4_choice2, 6));

    pages[5] = new Page(R.drawable.page5, R.string.page5);

    pages[6] = new Page(R.drawable.page6, R.string.page6);

}

public Page getPage(int pageNumber) {

    if(pageNumber >= pages.length){
        pageNumber = 0;
    }
    return pages[pageNumber];
}

}

package com.teamtreehouse.interactivestory.ui;

import android.content.Intent; import android.content.res.Resources; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.Button; import android.widget.EditText;

import com.teamtreehouse.interactivestory.R;

public class MainActivity extends AppCompatActivity {

private EditText nameField;
private Button startButton;

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

    nameField = (EditText)findViewById(R.id.nameEditText);
    startButton = (Button)findViewById(R.id.startButton);

    startButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String name = nameField.getText().toString();
            startStory(name);
        }
    });
}

private void startStory(String name) {
    Intent intent = new Intent(this, StoryActivity.class);
    Resources resources = getResources();
    String key = resources.getString(R.string.key_name);
    intent.putExtra(key, name);
    startActivity(intent);
}

}

package com.teamtreehouse.interactivestory.ui;

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

import com.teamtreehouse.interactivestory.R; import com.teamtreehouse.interactivestory.model.Choice; import com.teamtreehouse.interactivestory.model.Page; import com.teamtreehouse.interactivestory.model.Story;

public class StoryActivity extends AppCompatActivity {

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

private Story story;
private ImageView storyImageView;
private TextView storyTextView;
private Button choice1Button;
private Button choice2Button;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_story);


    storyImageView = (ImageView)findViewById(R.id.storageImageView);
    storyTextView = (TextView)findViewById(R.id.storyTextView);
    choice1Button = (Button)findViewById(R.id.choice1Button);
    choice2Button = (Button)findViewById(R.id.choice2Button);


    Intent intent = getIntent();
    String name = intent.getStringExtra(getString(R.string.key_name));
    if (name == null || name.isEmpty()) {
        name = "Friend";
    }
    Log.d(TAG, name);
    loadPage(0);
}

private void loadPage(int pageNumber) {

    Page page = story.getPage(pageNumber);

    Drawable image = ContextCompat.getDrawable(this, page.getImageId());
    storyImageView.setImageDrawable(image);

}

I really don't know how to solve it ...