Try this way:
Mails attachment open
File file = new File(yourdownloadfilePATH);
if ((download_file_name.endsWith(".pdf")) || (download_file_name.endsWith(".PDF"))){
if(file.exists() && file.length()!=0){
Intent intent = new Intent();
intent.setClassName("com.adobe.reader","com.adobe.reader.AdobeReader");
intent.setAction(android.content.Intent.ACTION_VIEW);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
Uri uri = Uri.fromFile(file);
intent.setDataAndType(uri, "application/pdf");
try {
startActivity(intent);
} catch (Exception e) {
AlertDialog.Builder builder = new AlertDialog.Builder(youractivity.this);
builder.setTitle("No Application Found");
builder.setMessage("Download application from Android Market?");
builder.setPositiveButton(
"Yes, Please",
new DialogInterface.OnClickListener() {
@Override
public void onClick(
DialogInterface dialog,
int which) {
Intent marketIntent = new Intent(
Intent.ACTION_VIEW);
marketIntent.setData(Uri
.parse("market://details?id=com.adobe.reader"));
startActivity(marketIntent);
}
});
builder.setNegativeButton("No, Thanks",
null);
builder.create().show();
}
}
} else if ((download_file_name.endsWith(".jpg"))|| (download_file_name.endsWith(".bmp"))||
(download_file_name.endsWith(".BMP"))||(download_file_name.endsWith(".png"))|| (download_file_name.endsWith(".PNG"))||(download_file_name.endsWith(".gif"))|| (download_file_name.endsWith(".GIF"))||
(download_file_name.endsWith(".JPG"))) {
Intent intent = new Intent();
intent.setAction(android.content.Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(file), "image/*");
startActivity(intent);
}
else if ((download_file_name.endsWith(".txt"))) {
Intent intent = new Intent();
intent.setAction(android.content.Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(file), "text/html");
startActivity(intent);
}