[英]Check if a property of a custom object ArrayList is an empty string or not?
如果自定義對象Arraylist（arrQues）的代碼屬性不包含任何內容，我想隱藏WebView對象（txtCode）。
if (arrQues.get(count).code.isEmpty())
txtCode.setVisibility(View.GONE);
它是從數據庫表中獲取的自定義對象的ArrayList，如下所示
如果代碼屬性包含代碼，那么我已動態添加規則到布局，如下所示：
if (!(arrQues.get(count).code.isEmpty())) {
submit_params.removeRule(RelativeLayout.BELOW);
submit_params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
submit_params.bottomMargin = (int) convertPxToDp(getContext(), convertDpToPx(getContext(), 15));
main_params.addRule(RelativeLayout.ABOVE, submitContainer.getId());
mainContainer.setLayoutParams(main_params);
submitContainer.setLayoutParams(submit_params);
}
這兩個問題只出現在我使用的時候出現... arrQues.get（count）.code.isEmpty（）我還嘗試使用“”代替isEmpty（）甚至是null，但結果是相同的。
另外我注意到的只是那些從數據庫中加載的問題，這些問題在代碼列中都有。
下面是Java文件的完整代碼
public class QuestionsFragment extends Fragment implements View.OnClickListener {
TextView txtTimer, txtStatus;
LinearLayout boxA, boxB, boxC, boxD, mainContainer;
RelativeLayout submitContainer;
RelativeLayout.LayoutParams submit_params;
RelativeLayout.LayoutParams main_params;
ScrollView scrollView;
Button btnSubmit;
DBHelper dbHelper;
SharedPreferences sharedPreferences;
TextView txtQues;
WebView txtCode;
TextView txtOptA, txtOptB, txtOptC, txtOptD;
String ans;
ArrayList<QuestionModal> arrQues = new ArrayList<>();
ArrayList<String> arrAnswers = new ArrayList<>();
CountDownTimer countDownTimer;
boolean timerSwitch;
int selectedVal, id;
int curr_quesNo = 0;
int count = 0;
int right = 0;
int non_attempted = 0;
public QuestionsFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_questions, container, false);
txtQues = view.findViewById(R.id.txtQues);
txtOptA = view.findViewById(R.id.txtOptionA);
txtOptB = view.findViewById(R.id.txtOptionB);
txtOptC = view.findViewById(R.id.txtOptionC);
txtOptD = view.findViewById(R.id.txtOptionD);
txtCode = view.findViewById(R.id.txtCode);
txtStatus = view.findViewById(R.id.txtStatus);
boxA = view.findViewById(R.id.boxA);
boxB = view.findViewById(R.id.boxB);
boxC = view.findViewById(R.id.boxC);
boxD = view.findViewById(R.id.boxD);
scrollView = view.findViewById(R.id.scrollView);
btnSubmit = view.findViewById(R.id.btnSubmit);
submitContainer = view.findViewById(R.id.submitContainer);
mainContainer = view.findViewById(R.id.mainContainer);
submit_params = new RelativeLayout.LayoutParams(MATCH_PARENT, WRAP_CONTENT);
main_params = new RelativeLayout.LayoutParams(MATCH_PARENT, WRAP_CONTENT);
sharedPreferences = getActivity().getSharedPreferences("PrefFile", MODE_PRIVATE);
timerSwitch = sharedPreferences.getBoolean("timer_switch", true);
selectedVal = sharedPreferences.getInt("selectedVal", 10);
dbHelper = DBHelper.getDB(getActivity(), sharedPreferences.getString("db_name", null));
if (!dbHelper.checkDB()) {
dbHelper.createDB(getActivity());
}
dbHelper.openDB();
String levelKey = sharedPreferences.getString("level_key", null);
arrQues = dbHelper.getQues(levelKey, selectedVal);
loadQues(timerSwitch);
txtTimer = view.findViewById(R.id.txtTimer);
switch (sharedPreferences.getString("db_name", null)) {
case "Android":
((MainActivity) getActivity()).setFragTitle("Android Quiz");
// topicLogo.setImageResource(R.drawable.ic_nature_people_black_24dp);
break;
case "Java":
((MainActivity) getActivity()).setFragTitle("Java Quiz");
// topicLogo.setImageResource(R.drawable.ic_nature_people_black_24dp);
break;
case "C":
((MainActivity) getActivity()).setFragTitle("C Quiz");
((MainActivity) getActivity()).setFragLogo(R.drawable.ic_home_black_24dp);
break;
case "C++":
((MainActivity) getActivity()).setFragTitle("C++ Quiz");
break;
case "Python":
((MainActivity) getActivity()).setFragTitle("Python Quiz");
break;
case "Kotlin":
((MainActivity) getActivity()).setFragTitle("Kotlin Quiz");
break;
}
btnSubmit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (timerSwitch)
countDownTimer.cancel();
if (id == 0) {
non_attempted++;
arrAnswers.add("NotAttempted");
Toast.makeText(getActivity(), "Not Attempted!", Toast.LENGTH_SHORT).show();
}
switch (id) {
case R.id.boxA:
arrAnswers.add("A");
break;
case R.id.boxB:
arrAnswers.add("B");
break;
case R.id.boxC:
arrAnswers.add("C");
break;
case R.id.boxD:
arrAnswers.add("D");
break;
}
if ((id == R.id.boxA && ans.equals("A"))
|| (id == R.id.boxB && ans.equals("B"))
|| (id == R.id.boxC && ans.equals("C"))
|| (id == R.id.boxD && ans.equals("D"))) {
right++;
count++;
Toast.makeText(getActivity(), "RIGHT!", Toast.LENGTH_SHORT).show();
if (count < arrQues.size()) {
loadQues(timerSwitch);
} else {
sendResult();
}
} else {
count++;
if (count < arrQues.size()) {
loadQues(timerSwitch);
} else {
sendResult();
}
}
}
});
return view;
}
public void setBtnDefault() {
boxA.setBackgroundColor(getResources().getColor(android.R.color.transparent));
boxB.setBackgroundColor(getResources().getColor(android.R.color.transparent));
boxC.setBackgroundColor(getResources().getColor(android.R.color.transparent));
boxD.setBackgroundColor(getResources().getColor(android.R.color.transparent));
}
public void sendResult() {
int attempted = selectedVal - non_attempted;
Gson gson = new Gson();
String jsonAnswers = gson.toJson(arrAnswers);
String jsonQues = gson.toJson(arrQues);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putInt("right_key", right);
editor.putInt("wrong_key", attempted - right);
editor.putInt("total_key", selectedVal);
editor.putInt("attempted_key", attempted);
editor.putString("arr_answers", jsonAnswers);
editor.putString("arr_ques", jsonQues);
editor.commit();
((MainActivity) getActivity()).AddFrag(new ResultFragment(), 1);
}
public void LoadTimer() {
countDownTimer = new CountDownTimer(60000, 1000) {
@Override
public void onTick(long millisUntilFinished) {
txtTimer.setText("0:" + millisUntilFinished / 1000);
}
@SuppressLint("SetTextI18n")
@Override
public void onFinish() {
txtTimer.setText("Time Over");
}
};
}
@SuppressLint("NewApi")
public void loadQues(boolean timer_switch) {
try {
id = 0;
setBtnDefault();
if (timer_switch) {
LoadTimer();
countDownTimer.start();
}
curr_quesNo++;
txtStatus.setText(curr_quesNo + "/" + selectedVal);
txtOptC.setVisibility(View.VISIBLE);
txtOptD.setVisibility(View.VISIBLE);
txtCode.setVisibility(View.VISIBLE);
main_params.removeRule(RelativeLayout.ABOVE);
submit_params.removeRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
submit_params.addRule(RelativeLayout.BELOW, mainContainer.getId());
submit_params.topMargin = (int) convertPxToDp(getContext(), convertDpToPx(getContext(), 70));
mainContainer.setLayoutParams(main_params);
submitContainer.setLayoutParams(submit_params);
txtQues.setText(arrQues.get(count).ques);
txtOptA.setText(arrQues.get(count).optionA);
txtOptB.setText(arrQues.get(count).optionB);
txtOptC.setText(arrQues.get(count).optionC);
txtOptD.setText(arrQues.get(count).optionD);
txtCode.loadDataWithBaseURL(null, arrQues.get(count).code, "text/html", null, null);
if (txtOptC.getText().toString().isEmpty())
txtOptC.setVisibility(View.GONE);
if (txtOptD.getText().toString().isEmpty())
txtOptD.setVisibility(View.GONE);
if (arrQues.get(count).code.isEmpty())
txtCode.setVisibility(View.GONE);
if (!(arrQues.get(count).code.isEmpty())) {
submit_params.removeRule(RelativeLayout.BELOW);
submit_params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
submit_params.bottomMargin = (int) convertPxToDp(getContext(), convertDpToPx(getContext(), 15));
main_params.addRule(RelativeLayout.ABOVE, submitContainer.getId());
mainContainer.setLayoutParams(main_params);
submitContainer.setLayoutParams(submit_params);
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
scrollView.arrowScroll(View.FOCUS_DOWN);
}
}, 1000);
}
ans = arrQues.get(count).answer;
boxA.setOnClickListener(this);
boxB.setOnClickListener(this);
boxC.setOnClickListener(this);
boxD.setOnClickListener(this);
} catch (Exception e) {
((MainActivity) getActivity()).AddFrag(new QuestionsFragment(), 1);
}
}
@Override
public void onClick(View v) {
setBtnDefault();
id = v.getId();
v.setBackgroundColor(getResources().getColor(R.color.colorPrimary));
}
public float convertDpToPx(Context context, float dp) {
return dp * context.getResources().getDisplayMetrics().density;
}
public float convertPxToDp(Context context, float px) {
return px / context.getResources().getDisplayMetrics().density;
}
}
我解決了所有問題，因為arrQues.get（count）.code從數據庫中獲取空值（“Code”列具有空值）。 一旦我用空字符串替換空值“”isEmpty（）完美地工作。 我猜isEmpty（）不能使用空值，只適用於空字符串。
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