[英]Cannot cast EditText into TextView in a custom adapter
我们目前正在开发一个项目,无法解决这个怪异的NullPointerException。 我们必须将特定的EditText转换为TextView才能使GridView正常工作。 现在的问题是,所有教程似乎都在使用Activity,而我们在使用Fragment。 我们的“ MainActivity”就在这里初始化一些启动器(启动画面,简介滑块等)。 所有其他内容都发生在我们的“ HomeFragment”中。 目的是捕获图片,写标题和一些内容,然后将其保存到SQLite数据库中,该数据库以后可用于在GridView中显示它。
我们使用了这个家伙(github)模板来创建我们自己的数据库(并重写了一些东西,因为我们正在使用Fragments)。
阅读代码时请耐心等待,它尚未最终确定。 大量垃圾代码仍在其中。
FragmentHome.class
public class FragmentHome extends Fragment {
private ImageButton mUnicornButton;
private ImageButton mBaseballbatButton;
private ImageButton mExplosionButton;
private ImageButton mCowButton;
private ImageButton mShitButton;
private ImageButton mPenguinButton;
private final int REQUEST_GALLERY_CODE = 999;
EditText edtTitle, edtContent;
Button btnAdd, btnChoose;
private ImageView mImageView;
protected View mView;
private static final int CAMERA_REQUEST = 1888;
public FragmentHome() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
}
public static SQLiteHelper sqLiteHelper;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_home, container, false);
this.mView = v;
initUI(v);
sqLiteHelper = new SQLiteHelper(getActivity().getApplicationContext(), "ListDB.sqlite",null,1);
sqLiteHelper.queryData("CREATE TABLE IF NOT EXISTS DBLIST(Id INTEGER PRIMARY KEY AUTOINCREMENT, title VARCHAR, content VARCHAR, image BLOB)");
btnChoose.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
ActivityCompat.requestPermissions(getActivity(),new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},REQUEST_GALLERY_CODE);
}
});
Button photoButton = v.findViewById(R.id.add_foto);
photoButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, CAMERA_REQUEST);
}
});
btnAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
try{
sqLiteHelper.insertData(
edtTitle.getText().toString().trim(),
edtContent.getText().toString().trim(),
imageViewToByte(mImageView)
);
Toast.makeText(getActivity().getApplicationContext(),"Added",Toast.LENGTH_SHORT).show();
edtTitle.setText("");
edtContent.setText("");
mImageView.setImageResource(R.mipmap.ic_launcher_round);
} catch(Exception e){
e.printStackTrace();
}
}
});
return v;
}
private byte[] imageViewToByte(ImageView image) {
Bitmap bitmap = ((BitmapDrawable)image.getDrawable()).getBitmap();
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG,0,stream);
byte[] byteArray = stream.toByteArray();
return byteArray;
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults){
if(requestCode == REQUEST_GALLERY_CODE){
if(grantResults.length >0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
Intent intent = new Intent(Intent.ACTION_PICK);
intent.setType("image/*");
startActivityForResult(intent, REQUEST_GALLERY_CODE);
}
else {
Toast.makeText(getActivity().getApplicationContext(),"No Permissions",Toast.LENGTH_SHORT).show();
}
return;
}
super.onRequestPermissionsResult(requestCode,permissions,grantResults);
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data){
if(requestCode == CAMERA_REQUEST){
if(resultCode == Activity.RESULT_OK){
Bitmap bmp = (Bitmap) data.getExtras().get("data");
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
Bitmap bitmap = BitmapFactory.decodeByteArray(byteArray,0,byteArray.length);
mImageView.setImageBitmap(bitmap);
}
}
}
private void initUI(View v) {
[...] //initializes everything using findViewById()
}
}
DBListAdapter.class(我们的自定义适配器)
public class DBListAdapter extends BaseAdapter{
private Context context;
private int layout;
private ArrayList<DBList> dblistsList;
public DBListAdapter(Context context, int layout, ArrayList<DBList> dblistsList) {
this.context = context;
this.layout = layout;
this.dblistsList = dblistsList;
}
@Override
public int getCount() {
return dblistsList.size();
}
@Override
public Object getItem(int position) {
return dblistsList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
private class ViewHolder{
ImageView imageView;
TextView txtTitle, txtContent;
}
@Override
public View getView(int position, View view, ViewGroup viewGroup) {
View row = view;
ViewHolder holder = new ViewHolder();
if(row==null){
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(layout, null);
holder.txtTitle = row.findViewById(R.id.input_title);
holder.txtContent = row.findViewById(R.id.input_content);
holder.imageView = row.findViewById(R.id.fotoView);
row.setTag(holder);
}
else{
holder = (ViewHolder) row.getTag();
}
DBList dbList = dblistsList.get(position);
holder.txtTitle.setText(dbList.getTitle());
holder.txtContent.setText(dbList.getContent());
byte[] dblistImage = dbList.getImage();
Bitmap bitmap = BitmapFactory.decodeByteArray(dblistImage, 0, dblistImage.length);
holder.imageView.setImageBitmap(bitmap);
return row;
}
}
问题出在此适配器中。
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference at s***.d***.u***.th***ive.DBListAdapter.getView(DBListAdapter.java:78)
我们无法弄清楚如何将EditText从fragment_home.xml强制转换为TextView,这是ViewHolder所需的。
fragment_home.xml
[...]
<ImageView
android:id="@+id/fotoView"
android:layout_width="match_parent"
android:layout_height="250dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:background="@color/Gainsboro"
app:srcCompat="@android:drawable/ic_menu_camera" />
<EditText
android:id="@+id/input_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Title"
android:inputType="text"
android:maxLines="1"
android:textAlignment="center"
android:layout_above="@+id/input_content"
android:layout_alignParentStart="true" />
<EditText
android:id="@+id/input_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/hint_what"
android:inputType="textMultiLine"
android:textAlignment="center"
android:layout_above="@+id/linearLayout"
android:layout_alignParentStart="true"
android:layout_marginBottom="33dp" /> [...]
任何帮助将不胜感激,我的头脑现在正在燃烧,我当然不知道如何解决这个问题。 如果您需要更多,请问我。 Kinda现在很累,因此可能会重播。
okey ..首先,您需要创建一个新的xml文件并根据需要命名它。...假设它的名称是list_reycle_view,然后将这些视图传输到该文件。
<ImageView
android:id="@+id/fotoView"
android:layout_width="match_parent"
android:layout_height="250dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:background="@color/Gainsboro"
app:srcCompat="@android:drawable/ic_menu_camera" />
<EditText
android:id="@+id/input_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Title"
android:inputType="text"
android:maxLines="1"
android:textAlignment="center"
android:layout_above="@+id/input_content"
android:layout_alignParentStart="true" />
<EditText
android:id="@+id/input_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/hint_what"
android:inputType="textMultiLine"
android:textAlignment="center"
android:layout_above="@+id/linearLayout"
android:layout_alignParentStart="true"
android:layout_marginBottom="33dp" />
然后..替换这些行
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(layout, null);
用这条线
row= LayoutInflater.from(context).inflate(R.layout.list_recycle_view,viewGroup,false);
并运行您的程序
ViewHolder holder = null;
if (row == null) {
LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(layout, null);
holder = new ViewHolder();
holder.txtTitle = row.findViewById(R.id.input_title);
holder.txtContent = row.findViewById(R.id.input_content);
holder.imageView = row.findViewById(R.id.fotoView);
row.setTag(holder);
}
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