Question

在 LoginActivity 中显示单个按钮
并且想要启动 UploadActivity ，如果 UploadActivity的列表包含任何其他数据显示提醒“在UploadActivity中找不到图像” < /强>

简而言之，我只想显示警告对话框，如果上传活动在列表中没有数据，则启动UploadActivity ...

btnCheckUpload.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub AlertDialog.Builder alertdialog = new AlertDialog.Builder(LoginActivity.this); alertdialog.setTitle(getResources().getString(R.string.app_name)); alertdialog.setMessage("No Images found in UploadActivity"); alertdialog.setPositiveButton("OK", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub } }); alertdialog.show(); } } });

UploadActivity.java： -

public class UploadActivity extends Activity { final private static int DIALOG_LOGIN = 1; EditText editPersonName, editPersonaEmail, editPersonTelephone, parental_email ; TextView editImageName ; String fileName; static ListView lstView; private Handler handler = new Handler();; static List <String> ImageList; String strPath; CheckBox chkOption3; TextView tv1, tv2; CheckBox chkOption1, chkOption2 ; int position ; static File f1; static String folder = null ; Intent i; Intent intent ; TextView textHeading1; static File[] files; static File file ; static List <String> it ; static String textHeading = null; // new Class DB final myDBClasss myDb = new myDBClasss(this); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_upload); textHeading1 = (TextView) findViewById(R.id.txtEventNameDate1); textHeading1.setText(CameraLauncherActivity.folder); /*** Get Images from SDCard ***/ ImageList = getSD(); // ListView and imageAdapter lstView = (ListView) findViewById(R.id.listView1); lstView.setAdapter(new ImageAdapter(this)); } public static List <String> getSD() { it = new ArrayList <String>(); String string = "/mnt/sdcard/Pictures/Awesome/"; f1 = new File (string+ CameraLauncherActivity.folder+ "/"); files = f1.listFiles (); for (int i = 0; i < files.length; i++) { file = files[i]; Log.d("Count",file.getPath()); it.add (file.getPath()); } return it; } public class ImageAdapter extends BaseAdapter { private Context context; public ImageAdapter(Context c) { // TODO Auto-generated method stub context = c; } public int getCount() { // TODO Auto-generated method stub return ImageList.size(); } public Object getItem(int position) { // TODO Auto-generated method stub return position; } public long getItemId(int position) { // TODO Auto-generated method stub return position; } public View getView(final int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub LayoutInflater inflater = (LayoutInflater) context .getSystemService(Context.LAYOUT_INFLATER_SERVICE); if (convertView == null) { convertView = inflater.inflate(R.layout.list_upload, null); } // ColImgName TextView txtName = (TextView) convertView.findViewById(R.id.ColImgName); strPath = ImageList.get(position).toString(); // Get File Name fileName = strPath.substring( strPath.lastIndexOf('/')+1, strPath.length() ); file = new File(strPath); @SuppressWarnings("unused") long length = file.length(); txtName.setText(fileName); // Image Resource ImageView imageView = (ImageView) convertView.findViewById(R.id.ColImgPath); final BitmapFactory.Options options = new BitmapFactory.Options(); options.inSampleSize = 8; Bitmap bm = BitmapFactory.decodeFile(strPath,options); imageView.setImageBitmap(bm); // ColStatus final ImageView txtStatus = (ImageView) convertView.findViewById(R.id.ColStatus); txtStatus.setImageResource(R.drawable.bullet_button); // progressBar final ProgressBar progress = (ProgressBar) convertView.findViewById(R.id.progressBar); progress.setVisibility(View.GONE); //btnUpload final ImageButton btnUpload = (ImageButton) convertView.findViewById(R.id.btnUpload); btnUpload.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { // Upload btnUpload.setEnabled(false); startUpload(position); } }); return convertView; } }

Answer 1

lstView.getChildCount()将返回组中的子项数。您可以查看。还存储ImageAdapter的引用然后使用adapter.getcount();

您也可以检查ImageList尺寸。

而不是

if (UploadActivity.lstView.getChildCount() > 0)

使用

if (imageList.size) > 0)

或 if (adapter.getcount() > 0)

Answer 2

ListView是一个View，调用listView.getChildCount（）表示：

<ListView>
  <TextView></TextView>
</ListView>

没有意义，因为ListView没有孩子。您需要做的是调用Adapter.getCount（）;

如果你很好地创建了适配器，它应该可以正常工作。

Answer 3

将您的getSD()设为公共静态，然后尝试在LogincActivity中访问它，如下所示：

 btnCheckUpload.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub
                   List<String> dt=new ArrayList<String>();
                    dt=UploadActivity.getSD();
                    if (dt.size()> 0) {
                    Intent intentUpload = new Intent(LoginActivity.this, UploadActivity.class);
                    startActivity(intentUpload);
                } else {
                    AlertDialog.Builder alertdialog = new AlertDialog.Builder(LoginActivity.this);
                    alertdialog.setTitle(getResources().getString(R.string.app_name));
                    alertdialog.setMessage("No Images found in UploadActivity");
                    alertdialog.setPositiveButton("OK", new DialogInterface.OnClickListener() 
                    {
                        public void onClick(DialogInterface dialog, int which) {
                            // TODO Auto-generated method stub
                            }
                        });
                    alertdialog.show();
                }
                }
            });

<强>编辑：

另一种方法是仅检查UploadActivity中的条件，如果没有找到数据，则只需显示提醒并点击提醒完成活动，如下所示：

   ImageAdapter adapter=new ImageAdapter(this);
  if(adapter.getCount()>0)
 {
     // ListView and imageAdapter
     lstView = (ListView) findViewById(R.id.listView1);
     lstView.setAdapter(new ImageAdapter(this));      
  else
  {

  AlertDialog.Builder alertdialog = new AlertDialog.Builder(LoginActivity.this);
                alertdialog.setTitle(getResources().getString(R.string.app_name));
                alertdialog.setMessage("No Images found in UploadActivity");
                alertdialog.setPositiveButton("OK", new DialogInterface.OnClickListener() 
                {
                    public void onClick(DialogInterface dialog, int which) {
                        finish(); //Finish your UploadActivity here.
                        }
                    });
                alertdialog.show();
       }

显示列表是否包含其他AlertDialog数据

3 个答案: