I have this error : java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setI

package com.xstudios.interactivestoryapp.ui;

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

import com.xstudios.interactivestoryapp.R; import com.xstudios.interactivestoryapp.model.Page; import com.xstudios.interactivestoryapp.model.Story;

public class StoryActivity extends AppCompatActivity { public static final String TAG = StoryActivity.class.getSimpleName(); private ImageView mImageView; private TextView mTextView; private Button mchoice1; private Button mchoice2; private String mName;

private Story mStory = new Story();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_story);
    Intent intent = getIntent();
           mName= intent.getStringExtra(getString(R.string.key_name));
    if(mName==null)
    {
        mName ="Friend";
    }

    Log.d(TAG, mName);
    mImageView = (ImageView) findViewById(R.id.imageView);
    mTextView = (TextView) findViewById(R.id.storytextView);
    mchoice1 = (Button) findViewById(R.id.Choicebutton1);
    mchoice2 = (Button) findViewById(R.id.ChoiceButton2);
    loadPage(0);
}


private void loadPage(int choice)
{

    final Page mCurrentPage = mStory.getPage(0);
    Drawable drawable = ResourcesCompat.getDrawable(getResources(), mCurrentPage.getImageid(),null);

mImageView.setImageDrawable(drawable); String pageText = mCurrentPage.getText(); pageText = String.format(pageText, mName); if(mCurrentPage.isFinal()) { mchoice1.setVisibility(View.INVISIBLE); mchoice2.setText("Play Again"); mchoice2.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { finish(); } }); } else { mTextView.setText(pageText); mchoice1.setText(mCurrentPage.getMchoice1().getText()); mchoice2.setText(mCurrentPage.getChoice2().getText());

mchoice1.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        int nextPage = mCurrentPage.getMchoice1().getNextPage();
        loadPage(nextPage);
    }
});
mchoice2.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        int nextPage = mCurrentPage.getChoice2().getNextPage();
        loadPage(nextPage);
    }
});

} }

}

this is my code in StoryActivity.java.(Interactive story App by Ben) please help me