如何在viewpager中将edittext中的数据发送到按钮单击时的共享首选项

Question

我有一个viewpager，它由三个xml文件组成，但最后一个xml文件有一个EditText和一个Button.Now我希望用户在EditText中键入的内容在按钮点击时保存到共享首选项中：这些是我的类

public class CustomPagerAdapter extends PagerAdapter {

private   Context context;

public CustomPagerAdapter(Context context) {
    this.context = context;
}
@Override
public Object instantiateItem(ViewGroup collection, int position) {


    ModelObject mo = ModelObject.values()[position];
    LayoutInflater inflater = LayoutInflater.from(context);
    ViewGroup layout = (ViewGroup) inflater.inflate(mo.getLayoutResId(), collection, false);

   Button butIntro = (Button) layout.findViewById(R.id.introStart);
   EditText= (EditText) layout.findViewById(R.id.introUsername);


    butIntro.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
    SharedPreferences sharepreff = getSharedPreferences("StartUpInfo", Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = sharepreff.edit();
    editor.putString("username",introUser.getText().toString());
    editor.apply();
        }
    });
    collection.addView(layout);
    return layout;
}


@Override
public void destroyItem(ViewGroup collection, int position, Object view) {
    collection.removeView((View) view);
}
@Override
public int getCount() {
    return ModelObject.values().length;
}

@Override
public boolean isViewFromObject(View view, Object object) {
    return view == object;
}

@Override
public CharSequence getPageTitle(int position) {
    ModelObject customPagerEnum = ModelObject.values()[position];
    return context.getString(customPagerEnum.getTitleResId());
}

}

public class intro extends AppCompatActivity {
EditText introUser;
TextView username;

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

    SharedPreferences pref = getSharedPreferences("ActivityPREF", Context.MODE_PRIVATE);
    if(pref.getBoolean("activity_executed", false)){
        Intent intent = new Intent(this, homeActivity.class);
        startActivity(intent);
        finish();
    } else {
        SharedPreferences.Editor ed = pref.edit();
        ed.putBoolean("activity_executed", true);
        ed.commit();
    }

    ViewPager intro =(ViewPager) findViewById(R.id.introviewpager);
    intro.setAdapter(new CustomPagerAdapter(this));
     introUser= (EditText) findViewById(R.id.introUsername);

}

   public void newStart(View view){

       Intent intent1 = new Intent(this, homeActivity.class);
      this.startActivity(intent1);
  }
  }

每次运行时应用程序都会崩溃。请允许任何人帮助我弄清楚我在这里做错了什么。谢谢