android - 在 GridView 中面临问题

Question

这里我正在开发一个应用程序，我必须使用 GridView 来根据客户要求显示一些图像。

在那个 GridView 中，我一次显示 2 行和 2 列，因此一次可以看到 4 个图像。现在用户想要做一些更改，并希望我创建一个 EditText，他可以在其中输入数字，根据该数字，GridView 应该更改其列和行。

是否有可能，因为我已经浏览了很多在线示例，而我所得到的只是在运行时更改 GridView 但具有固定的预定义行数和列数。但我没有找到任何示例，例如在运行时从 EditText 更改 GridView。

和类型的帮助将是可观的。

Answer 1

正如我在评论中提到的，您可以为您的 gridview 使用自定义 baseadapter，并将图像数量作为适配器类构造函数中的参数。下面是您可以用来实现此目的的代码 fragment 。

自定义 BaseAdapter

public class Adapter extends BaseAdapter {

private final Context context;
private final LayoutInflater inflater;
private final int numbers;

public Adapter(Context context, int numberOfImages) {
    this.context = context;
    this.numbers = numberOfImages;
    this.inflater = (LayoutInflater) this.context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

}

@Override
public int getCount() {
    //You need to return the numberOfImages here for 
    //the adapter to determine how many view you need to create.
    return numbers;
}

private class viewHolder {
    ImageView image;
    TextView image_desc;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    viewHolder holder;

    if (convertView == null) {
        convertView = inflater.inflate(R.layout.grid_item, null);
        holder = new viewHolder();
        holder.image = (ImageView) convertView.findViewById(R.id.image);
        holder.image_desc = (TextView) convertView
                .findViewById(R.id.img_desc);
        convertView.setTag(holder);
    }
    holder = (viewHolder) convertView.getTag();
    if (position % 2 == 0) {
        holder.image.setImageResource(R.drawable.ic_action_add_person);
        holder.image_desc.setText("change");
    }

    return convertView;
}

@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return 0;
}

}

您的主要 Activity : 在此 Activity 中，您需要要求用户输入他们想要查看的图像数量。当用户未输入值时，我没有添加任何类型的验证或错误消息，而是我捕获了可能的错误并使用它来分配默认值。您可以根据需要在此处应用其他类型的逻辑。

public class MainActivity extends Activity implements OnClickListener {

EditText text;
Button button;
int number;
private static final String NUMBER_OF_IMAGES = "numbers";

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

    text = (EditText) findViewById(R.id.text);
    button = (Button) findViewById(R.id.button);
    button.setOnClickListener(this);
}

@Override
public void onClick(View v) {

    try {
        number = Integer.parseInt(text.getText().toString());

        // if user enters 0 or negative number then the default value is set
        // to 2
        if (number < 1) {
            number = 2;
        }
    } catch (Exception e) {
        e.printStackTrace();
        // if user doesn't enter anything then code will catch 
        // classCastException and assign 2 as default value here
        number = 2;
    }
    // start this intent by putting this number in the bundle
    Intent i = new Intent(getApplicationContext(), SecondActivity.class);
    Bundle bundle = new Bundle();
    bundle.putInt(NUMBER_OF_IMAGES, number);
    i.putExtras(bundle);
    startActivity(i);
}
}

第二个 Activity :这是您定义和初始化 gridview 和适配器的 Activity 。确保您从之前的 Activity 中检索包并正确检索用户输入的数字。

public class SecondActivity extends Activity {
GridView grid;
Adapter adapter;

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

    Bundle bundle = getIntent().getExtras();
    int numbers = bundle.getInt(MainActivity.NUMBER_OF_IMAGES);

    grid = (GridView) findViewById(R.id.gridview);
    // depending upon your requirement you can also add logic here to set
    // the number of columns based on the number entered by the user
    setColumns(numbers);
    adapter = new Adapter(getApplicationContext(), numbers);
    grid.setAdapter(adapter);
}

@Override
protected void onResume() {
    super.onResume();
    adapter.notifyDataSetChanged();
}

/**
 * Method to set the number of columns depending upon user input for desired
 * grids. other attributes for the grid view can also be set her such as
 * width, height, background etc.
 * 
 * @param number
 */
public void setColumns(int number) {
    if (number > 0 && number < 10) {
        grid.setNumColumns(2);
    } else if (number >= 10 && number < 20) {
        grid.setNumColumns(4);
    } else {
        grid.setNumColumns(5);
    }
}
}

注意:这不是针对性能进行高度优化的代码，只是提供了一个如何实现所需功能的示例。