另一个类调用下面的 GridView 类，该类填充了来自解析服务器的图像，如果用户点击网格项，它会启动相同的 GridView 类不同的捆绑字符串，因此它可以从不同的解析数据库类中提取。现在，此时，当用户单击GridView项目（来自设置的第二个gridview）时，我希望它启动另一个活动类。
我尝试在onItemClick中执行if / else if语句，该语句采用＆＃34; PARSE_CLASS ＆＃34;捆绑的字符串，但我似乎无法让它工作。我对android编程比较陌生，所以我不知道最好的方法。
public class DisplayGrid extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
GridView gridView = null;
List<ParseObject> obj;
ProgressDialog loadProgress;
GridViewAdapter adapter;
Bundle extras = new Bundle();
GridViewAdapter itemGridAdapter;
private List<ImageList> imageArrayList = null;
private List<String> categoryNameArrayList = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.ws_display_grid);
imageArrayList = new ArrayList<ImageList>();
categoryNameArrayList = new ArrayList<String>();
gridView = (GridView) findViewById(R.id.gridView);
itemGridAdapter = new GridViewAdapter(DisplayGrid.this, imageArrayList);
gridView.setAdapter(itemGridAdapter);
new RemoteDataTask().execute();
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
Intent i = getIntent();
Bundle itemExtras = i.getExtras();
final String activeSupplier = itemExtras.getString("SUPPLIER");
String parseClass = extras.getString("PARSE_CLASS");
@Override
public void onItemClick(AdapterView<?> arg0, View v, int position,
long arg3) {
Intent t = new Intent(getApplicationContext(), DisplayGrid.class);
extras.putString("SUPPLIER", activeSupplier);
extras.putString("PARSE_CLASS", "Items");
t.putExtras(extras);
startActivity(t);
}
});
}//end onCreate method
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
@Override
public void onStart() {
super.onStart();
}
@Override
public void onStop() {
super.onStop();
}
//RemoteDataTask
private class RemoteDataTask extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
loadProgress = new ProgressDialog(DisplayGrid.this);
loadProgress.setTitle("Images");
loadProgress.setMessage("Loading...");
loadProgress.setIndeterminate(false);
loadProgress.show();
}
@Override
protected Void doInBackground(Void... params) {
try {
Intent i = getIntent();
Bundle extras = i.getExtras();
String parseClass = extras.getString("PARSE_CLASS");
String activeSupplier = extras.getString("SUPPLIER");
String category;
ParseQuery<ParseObject> query = new ParseQuery<>(parseClass);
query.whereEqualTo("username", activeSupplier);
obj = query.find();
if (parseClass == "Items") {
category = extras.getString("CATEGORY");
query.whereEqualTo("category", category);
}
for (ParseObject categories : obj) {
//get image
ParseFile image = (ParseFile) categories.get("image");
ImageList gridBlock = new ImageList();
gridBlock.setImage(image.getUrl());
imageArrayList.add(gridBlock);
Log.i("AppInfo", "image sent to imageArrayList");
String categoryName = null;
//get category name
if (categoryName == null) {
} else {
categoryName = categories.getString("categoryName");
categoryNameArrayList.add(categoryName);
Log.i("AppInfo", categoryName);
}
}
} catch (ParseException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void result) {
gridView = (GridView) findViewById(R.id.gridView);
adapter = new GridViewAdapter(DisplayGrid.this, imageArrayList);
gridView.setAdapter(adapter);
loadProgress.dismiss();
Log.i("AppInfo", "CategoryGrid Populated");
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1 && resultCode == RESULT_OK && data != null) {
Uri selectedImage = data.getData();
try {
Bitmap bitmapImage =
MediaStore.Images.Media.getBitmap
(this.getContentResolver(), selectedImage);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmapImage.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
//convert to parse file
ParseFile file = new ParseFile("Img.png", byteArray);
ParseObject object = new ParseObject("Categories");
object.put("username", ParseUser.getCurrentUser().getUsername());
object.put("image", file);
object.saveInBackground(new SaveCallback() {
@Override
public void done(ParseException e) {
if (e == null) {
Toast.makeText(getApplication().getBaseContext(), "Your image has been saved", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(getApplication().getBaseContext(), "Upload failed, please try again", Toast.LENGTH_SHORT).show();
}
}
});
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getApplication().getBaseContext(), "Upload failed, please try again", Toast.LENGTH_SHORT).show();
}
}
}
//begin getTitle method
//begin createMenu
@Override
public boolean onCreateOptionsMenu(Menu menu) {
new MenuInflater(getApplication())
.inflate(R.menu.options, menu);
return (super.onCreateOptionsMenu(menu));
}
//end createMenu
//begin onOptionsItemSelected
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.manufacturers) {
Intent i = new Intent(getApplicationContext(), SupplierList.class);
startActivity(i);
return true;
} else if (item.getItemId() == R.id.add) {
Intent i = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(i, 1);
return true;
} else if (item.getItemId() == R.id.sign_out) {
ParseUser.logOut();
Intent i = new Intent(getApplicationContext(), MainActivity.class);
startActivity(i);
return true;
}
return (super.onOptionsItemSelected(item));
}
//end onOptionsItemSelected
}
这就是我尝试过的。当我尝试这个时，第二个 GridView 将无法加载。因此，我猜测我第二次无法检索＆＃34; PARSE_CLASS＆＃34; 捆绑字符串。
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
Intent i = getIntent();
Bundle itemExtras = i.getExtras();
final String activeSupplier = itemExtras.getString("SUPPLIER");
String parseClass = extras.getString("PARSE_CLASS");
@Override
public void onItemClick(AdapterView<?> arg0, View v, int position,
long arg3) {
if (parseClass == "Categories") {
Intent t = new Intent(getApplicationContext(), DisplayGrid.class);
extras.putString("SUPPLIER", activeSupplier);
extras.putString("PARSE_CLASS", "Items");
t.putExtras(extras);
startActivity(t);
} else if(parseClass == "Items"){
Intent t = new Intent(getApplicationContext(), ItemDisplay.class);
//extras.putString("SUPPLIER", activeSupplier);
//extras.putString("PARSE_CLASS", "Items");
//t.putExtras(extras);
startActivity(t);
}
}
});
ANSWER 有人在reddit上学习编程很好，可以指出我遇到了字符串比较的问题。不得不使用
if(parseClass.equals("Categories")){}
而不是
if(parseClass == "Categories"){}
我觉得自己像个白痴，希望其他人能从这个长期的灾难性努力中受益。
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
Intent t = getIntent();
Bundle itemExtras = t.getExtras();
String activeSupplier = itemExtras.getString("SUPPLIER");
String parseClass = itemExtras.getString("PARSE_CLASS");
@Override
public void onItemClick(AdapterView<?> arg0, View v, int position,
long arg3) {
Log.i("AppInfo", parseClass);
if (parseClass.equals("Categories")) {
Log.i("AppInfo", parseClass);
Intent t = new Intent(getApplicationContext(), DisplayGrid.class);
String categoryName = categoryNameArrayList.get(position);
itemExtras.putString("SUPPLIER", activeSupplier);
itemExtras.putString("PARSE_CLASS", "Items");
itemExtras.putString("CATEGORY_NAME", categoryName);
t.putExtras(itemExtras);
startActivity(t);
} else if (parseClass.equals("Items")) {
Intent t = new Intent(getApplicationContext(), ItemDisplay.class);
//extras.putString("SUPPLIER", activeSupplier);
//extras.putString("PARSE_CLASS", "Items");
//t.putExtras(extras);
startActivity(t);
}
}
});
答案 0 :(得分：0)
public class DisplayGrid extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
GridView gridView = null;
List<ParseObject> obj;
ProgressDialog loadProgress;
GridViewAdapter adapter;
Bundle extras = new Bundle();
GridViewAdapter itemGridAdapter;
private List<ImageList> imageArrayList = null;
private List<String> categoryNameArrayList = null;
String activeSupplier;
String parseClass;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.ws_display_grid);
imageArrayList = new ArrayList<ImageList>();
categoryNameArrayList = new ArrayList<String>();
Intent i = getIntent();
if (null != i) {
Bundle itemExtras = i.getExtras();
activeSupplier = itemExtras.getString("SUPPLIER");
parseClass = itemExtras.getString("PARSE_CLASS");
}
RemoteDataTask remoteDataAsync = new RemoteDataTask();
remoteDataAsync.execute();
if(remoteDataAsync.getStatus() == AsyncTask.Status.PENDING){
// My AsyncTask has not started yet
}
if(remoteDataAsync.getStatus() == AsyncTask.Status.RUNNING){
// My AsyncTask is currently doing work in doInBackground()
}
if(remoteDataAsync.getStatus() == AsyncTask.Status.FINISHED){
// My AsyncTask is done and onPostExecute was called
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View v, int position,
long arg3) {
Intent t = new Intent(getApplicationContext(), DisplayGrid.class);
extras.putString("SUPPLIER", activeSupplier);
extras.putString("PARSE_CLASS", parseClass);
t.putExtras(extras);
startActivity(t);
}
});
}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
@Override
public void onStart() {
super.onStart();
}
@Override
public void onStop() {
super.onStop();
}
//RemoteDataTask
private class RemoteDataTask extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
loadProgress = new ProgressDialog(DisplayGrid.this);
loadProgress.setTitle("Images");
loadProgress.setMessage("Loading...");
loadProgress.setIndeterminate(false);
loadProgress.show();
}
@Override
protected Void doInBackground(Void... params) {
try {
Intent i = getIntent();
Bundle extras = i.getExtras();
String parseClass = extras.getString("PARSE_CLASS");
String activeSupplier = extras.getString("SUPPLIER");
String category;
ParseQuery<ParseObject> query = new ParseQuery<>(parseClass);
query.whereEqualTo("username", activeSupplier);
obj = query.find();
if (parseClass == "Items") {
category = extras.getString("CATEGORY");
query.whereEqualTo("category", category);
}
for (ParseObject categories : obj) {
//get image
ParseFile image = (ParseFile) categories.get("image");
ImageList gridBlock = new ImageList();
gridBlock.setImage(image.getUrl());
imageArrayList.add(gridBlock);
Log.i("AppInfo", "image sent to imageArrayList");
String categoryName = null;
//get category name
if (categoryName == null) {
} else {
categoryName = categories.getString("categoryName");
categoryNameArrayList.add(categoryName);
Log.i("AppInfo", categoryName);
}
}
} catch (ParseException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void result) {
adapter = new GridViewAdapter(DisplayGrid.this, imageArrayList);
gridView.setAdapter(adapter);
loadProgress.dismiss();
Log.i("AppInfo", "CategoryGrid Populated");
}//end onCreate method
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1 && resultCode == RESULT_OK && data != null) {
Uri selectedImage = data.getData();
try {
Bitmap bitmapImage =
MediaStore.Images.Media.getBitmap
(this.getContentResolver(), selectedImage);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmapImage.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
//convert to parse file
ParseFile file = new ParseFile("Img.png", byteArray);
ParseObject object = new ParseObject("Categories");
object.put("username", ParseUser.getCurrentUser().getUsername());
object.put("image", file);
object.saveInBackground(new SaveCallback() {
@Override
public void done(ParseException e) {
if (e == null) {
Toast.makeText(getApplication().getBaseContext(), "Your image has been saved", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(getApplication().getBaseContext(), "Upload failed, please try again", Toast.LENGTH_SHORT).show();
}
}
});
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getApplication().getBaseContext(), "Upload failed, please try again", Toast.LENGTH_SHORT).show();
}
}
}
//begin getTitle method
//begin createMenu
@Override
public boolean onCreateOptionsMenu(Menu menu) {
new MenuInflater(getApplication())
.inflate(R.menu.options, menu);
return (super.onCreateOptionsMenu(menu));
}
//end createMenu
//begin onOptionsItemSelected
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.manufacturers) {
Intent i = new Intent(getApplicationContext(), SupplierList.class);
startActivity(i);
return true;
} else if (item.getItemId() == R.id.add) {
Intent i = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(i, 1);
return true;
} else if (item.getItemId() == R.id.sign_out) {
ParseUser.logOut();
Intent i = new Intent(getApplicationContext(), MainActivity.class);
startActivity(i);
return true;
}
return (super.onOptionsItemSelected(item));
}
//end onOptionsItemSelected
}