title: HashMap<String, List<String>> may not contain objects of type 'integer'
body: <p>I have written the code for displaying an ExpandableListView on android studio.
  This is the code for the ExplandableListView:</p>
  
  <pre><code>public class Recipes extends AppCompatActivity implementsView.OnClickListener           {
  ExpandableListView exp;
  EditText t;
  Button b;
  
  
  HashMap&lt;String, List&lt;String&gt;&gt; Movies_category;
  List&lt;String&gt; Movies_list;
  ExpandableListView Exp_list;
  MoviesAdapter adapter;
  
  protected void onCreate(Bundle savedInstanceState) {
      setTheme(R.style.NoActionBar);
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_recipes);
      t = (EditText) findViewById(R.id.t);
      b = (Button) findViewById(R.id.b);
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_recipes);
      Exp_list = (ExpandableListView) findViewById(R.id.exp_list);
      Movies_category = DataProvider.getInfo();
      Movies_list = new ArrayList&lt;String&gt;(Movies_category.keySet());
      adapter = new MoviesAdapter(this, Movies_category, Movies_list);
      Exp_list.setAdapter(adapter);
      t.setOnClickListener(this);
      b.setOnClickListener(this);
  }
  
  @Override
  public void onClick(View v) {
      startActivity(new Intent(this, Choose.class));
      }
  }
  </code></pre>
  
  <p>And this for the methods to perform operations:</p>
  
  <pre><code>public class RecipeAda extends BaseExpandableListAdapter{
  private Context ctx;
  private HashMap&lt;String, List&lt;String&gt;&gt; recipes;
  private List&lt;String&gt; ingr;
  public RecipeAda(Context ctx,HashMap&lt;String, List&lt;String&gt;&gt;recipes, List&lt;String&gt; ingr)
  {
       this.ctx=ctx;
      this.recipes=recipes;
      this.ingr=ingr;
  }
  
  @Override
  public int getGroupCount() {
      return recipes.size();
  }
  
  @Override
  public int getChildrenCount(int groupPosition) {
      return recipes.get(ingr.get(groupPosition)).size();
  }
  
  
  @Override
  public Object getGroup(int groupPosition) {
      return recipes.get(groupPosition);
  }
  
  @Override
  public Object getChild(int parent, int child) {
      return recipes.get(ingr.get(parent)).get(child);
  }
  
  
  @Override
  public long getGroupId(int groupPosition) {
      return groupPosition;
  }
  
  
  @Override
  public long getChildId(int parent, int child) {
      return child;
  }
  
  @Override
  public boolean hasStableIds() {
      return false;
  }
  
  @Override
  public View getGroupView(int parent, boolean isExpanded, View convertView, ViewGroup parentview) {
      String grptit= (String) getGroup(parent);
      if (convertView==null)
      {
          LayoutInflater inf= (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
          convertView=inf.inflate(R.layout.parent_layout,parentview,false);
      }
      TextView pa= (TextView) convertView.findViewById(R.id.textView4);
      pa.setTypeface(null, Typeface.BOLD);
      pa.setText(grptit);
      return convertView;
  }
  
  
  @Override
  public View getChildView(int parent, int child, boolean lastChild, View convertView, ViewGroup parentview) {
      String childtitle= (String) getChild(parent,child);
      if (convertView==null)
      {
          LayoutInflater inf= (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
          convertView=inf.inflate(R.layout.child_layout,parentview,false);
      }
      TextView ch= (TextView) convertView.findViewById(exp_list);
      ch.setText(childtitle);
      return convertView;
  }
  
  @Override
  public boolean isChildSelectable(int groupPosition, int childPosition) {
      return false;
  }}
  </code></pre>
  
  <p>It shows warning at the "groupPosition" in function definition of:    </p>
  
  <pre><code>@Override
  public Object getGroup(int groupPosition) {
      return recipes.get(groupPosition);
  }
  </code></pre>
  
  <p>when hovered over it, says <code>HashMap&lt;String, List&lt;String&gt;&gt; may not contain objects of type 'integer'</code><br>
  How do I correct this?<br>
  Also, how do I accept the contents(string) from the user and save in the database?</p>