How to display data in an Android GridView?

To display data in an Android GridView, you need to follow these steps:

1. Create a layout file to display the view of each grid item. This layout file can contain an ImageView, a TextView, or any other view you want to display in each grid item.
2. Develop a custom adapter class that extends BaseAdapter and implements its methods. The adapter is responsible for binding data to each grid item in a GridView.
3. Instantiate a GridView in your activity or fragment, and set its adapter to the custom adapter you have created.
4. Set a click listener for the GridView in your activity or fragment to respond to user clicks on grid items.

Here is a simple example code to help you understand how to display data in a GridView.

Layout file grid_item.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/image_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

Custom adapter class GridAdapter.java:

public class GridAdapter extends BaseAdapter {
    private Context mContext;
    private List<DataItem> mDataItems;

    public GridAdapter(Context context, List<DataItem> dataItems) {
        mContext = context;
        mDataItems = dataItems;
    }

    @Override
    public int getCount() {
        return mDataItems.size();
    }

    @Override
    public Object getItem(int position) {
        return mDataItems.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view;
        ViewHolder holder;

        if (convertView == null) {
            LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = inflater.inflate(R.layout.grid_item, parent, false);

            holder = new ViewHolder();
            holder.imageView = view.findViewById(R.id.image_view);
            holder.textView = view.findViewById(R.id.text_view);

            view.setTag(holder);
        } else {
            view = convertView;
            holder = (ViewHolder) view.getTag();
        }

        DataItem dataItem = mDataItems.get(position);
        holder.imageView.setImageResource(dataItem.getImageResId());
        holder.textView.setText(dataItem.getText());

        return view;
    }

    private static class ViewHolder {
        ImageView imageView;
        TextView textView;
    }
}

Activity class MainActivity.java:

public class MainActivity extends AppCompatActivity {
    private GridView mGridView;
    private List<DataItem> mDataItems;
    private GridAdapter mAdapter;

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

        mGridView = findViewById(R.id.grid_view);

        mDataItems = new ArrayList<>();
        mDataItems.add(new DataItem(R.drawable.image1, "Item 1"));
        mDataItems.add(new DataItem(R.drawable.image2, "Item 2"));
        mDataItems.add(new DataItem(R.drawable.image3, "Item 3"));
        // 添加更多数据项...

        mAdapter = new GridAdapter(this, mDataItems);
        mGridView.setAdapter(mAdapter);

        mGridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                // 处理网格项点击事件
                DataItem dataItem = mDataItems.get(position);
                Toast.makeText(MainActivity.this, dataItem.getText(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}

This way, when you run this application, it will display data in a GridView and can respond to user clicking on each grid item.