如何使用tablayout和片段管理java文件[关闭]
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【中文标题】如何使用tablayout和片段管理java文件[关闭]【英文标题】：How to manage java file with tablayout and fragments [closed] 【发布时间】：2021-10-09 03:47:05 【问题描述】：我正在使用 firestore 开发一个简单的应用程序。在这种情况下，为了更好的功能和客户友好性，我将带有片段的 tablayout 概念输入到我的应用程序中。当我使用时，出现了一些错误。我试过了，但我无法修复它。所以我想要的是，影响这种错误的情况是什么？如果你熟悉我所说的，请帮助我。
this is the java file that i want to code in one fragment.
package com.example.work_home;
import android.app.AlertDialog;
import android.app.DatePickerDialog;
import android.content.Intent;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.Toast;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.google.android.material.textfield.TextInputEditText;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.firestore.DocumentReference;
import com.google.firebase.firestore.FirebaseFirestore;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;
import static android.content.ContentValues.TAG;
import static com.example.work_home.R.id.txt_select_leave;
public class Apply extends Fragment
private AutoCompleteTextView SelectLeave, LeaveType;
TextInputEditText FromDate, ToDate;
EditText Reason;
private DatePickerDialog dataPickerDialog_from;
private DatePickerDialog dataPickerDialog_to;
Button BtnSubmit;
BottomNavigationView BtnBottom;
View v;
FirebaseAuth auth = FirebaseAuth.getInstance();
FirebaseUser FUser = auth.getCurrentUser();
public String UserId = FUser.getUid();
private FirebaseFirestore db = FirebaseFirestore.getInstance();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
// Inflate the layout for this fragment
v = inflater.inflate(R.layout.fragment_apply, container, false);
return v;
SelectLeave = v.findViewById(txt_select_leave);
LeaveType = v.findViewById(R.id.txt_leave_type);
FromDate = v.findViewById(R.id.txt_from_user);
ToDate = v.findViewById(R.id.txt_to_user);
Reason = v.findViewById(R.id.txt_reason_user);
BtnSubmit = v.findViewById(R.id.btn_submit);
BtnBottom = v.findViewById(R.id.btn_bottom_navigation_leave);
BtnSubmit.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
String selectLeave = SelectLeave.getText().toString();
String leaveType = LeaveType.getText().toString();
String fromDate = FromDate.getText().toString();
String toDate = ToDate.getText().toString();
String reason = Reason.getText().toString();
DocumentReference documentReference = db.collection("users").document(UserId);
DocumentReference documentReference_two = documentReference.collection("ApplyLeave").document();
Map<String, Object> LeaveData = new HashMap<>();
LeaveData.put("u_select_leave", selectLeave);
LeaveData.put("u_leave-type", leaveType);
LeaveData.put("u_from_date", fromDate);
LeaveData.put("u_to_date", toDate);
LeaveData.put("u_reason", reason);
documentReference_two.set(LeaveData);
);
FromDate.setText(getTodayDate());
ToDate.setText(getTodayDate());
initDatePicker_from();
initDatePicker_to();
String[] Select_Leave = new String[]
"Casual Leave", "Sick Leave", "Annual Leave ", "Maternity Leave", "Paternity Leave"
, "Compensatory Off", "Other";
ArrayAdapter adapter = new ArrayAdapter<>(
Apply.this, R.layout.dropdown_item, Select_Leave
);
SelectLeave.setAdapter(adapter);
String[] Leave_Type = new String[]
"Full Day", "Half Day", "Other";
ArrayAdapter<String> adapter_one = new ArrayAdapter<>(
Apply.this, R.layout.dropdown_item, Leave_Type
);
LeaveType.setAdapter(adapter_one);
/*BtnBottom.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener()
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item)
switch (item.getItemId())
case R.id.logout:
Intent logout = new Intent(Apply.this, Login.class);
startActivity(logout);
overridePendingTransition(0, 0);
return true;
case R.id.home:
Intent home = new Intent(Apply_leave.this, Home.class);
startActivity(home);
overridePendingTransition(0, 0);
return true;
case R.id.user:
Intent user = new Intent(Apply_leave.this, UserProfile.class);
startActivity(user);
overridePendingTransition(0, 0);
return true;
/*case R.id.alerts:
Intent alerts = new Intent(Apply_leave.this, Notifications.class);
startActivity(alerts);
overridePendingTransition(0, 0);
return true;
return false;
);*/
private String getTodayDate()
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR);
int month = cal.get(Calendar.MONTH);
month = month + 1;
int day = cal.get(Calendar.DAY_OF_MONTH);
return makeDataString(day, month, year);
private void initDatePicker_from()
DatePickerDialog.OnDateSetListener dataSetListener_from = new DatePickerDialog.OnDateSetListener()
@Override
public void onDateSet(DatePicker view, int year, int month, int dayOfMonth)
month = month + 1;
String date_from = makeDataString(dayOfMonth, month, year);
FromDate.setText(date_from);
;
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR);
int month = cal.get(Calendar.MONTH);
int day = cal.get(Calendar.DAY_OF_MONTH);
int style = AlertDialog.THEME_HOLO_LIGHT;
dataPickerDialog_from = new DatePickerDialog(this, style, dataSetListener_from, year, month, day);
dataPickerDialog_from.getDatePicker().setMaxDate(System.currentTimeMillis());
private void initDatePicker_to()
DatePickerDialog.OnDateSetListener dataSetListener_to = new DatePickerDialog.OnDateSetListener()
@Override
public void onDateSet(DatePicker view, int year, int month, int dayOfMonth)
month = month + 1;
String date_to = makeDataString(dayOfMonth, month, year);
ToDate.setText(date_to);
;
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR);
int month = cal.get(Calendar.MONTH);
int day = cal.get(Calendar.DAY_OF_MONTH);
int style = AlertDialog.THEME_HOLO_LIGHT;
dataPickerDialog_to = new DatePickerDialog(this, style, dataSetListener_to, year, month, day);
dataPickerDialog_to.getDatePicker().setMaxDate(System.currentTimeMillis());
private String makeDataString(int dayOfMonth, int month, int year)
return getMonthFormat(month) + " " + dayOfMonth + " " + year;
private String getMonthFormat(int month)
if (month == 1)
return "JAN";
if (month == 2)
return "FEB";
if (month == 3)
return "MAR";
if (month == 4)
return "APR";
if (month == 5)
return "MAY";
if (month == 6)
return "JUN";
if (month == 7)
return "JUL";
if (month == 8)
return "AUG";
if (month == 9)
return "SEP";
if (month == 10)
return "OCT";
if (month == 11)
return "NOV";
if (month == 12)
return "DEC";
return "JAN";
public void openDatePicker_from(View view)
dataPickerDialog_from.show();
public void openDatePicker_to(View view)
dataPickerDialog_to.show();
*****这是我的 tablayout(main.xml) 文件的布局[在此处输入图片描述][1]
******这是apply.xml文件的布局******** [在此处输入图片描述][2]
这是我的适配器文件*****
package com.example.work_home;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentPagerAdapter;
import java.util.ArrayList;
public class VPAdapter extends FragmentPagerAdapter
private final ArrayList<Fragment> fragmentArrayList = new ArrayList<>();
private final ArrayList<String> fragmentTitle = new ArrayList<>();
public VPAdapter(@NonNull FragmentManager fm, int behavior)
super(fm, behavior);
@NonNull
@Override
public Fragment getItem(int position)
return fragmentArrayList.get(position);
@Override
public int getCount()
return fragmentArrayList.size();
public void addFragment(Fragment fragment, String title)
fragmentArrayList.add(fragment);
fragmentTitle.add(title);
@Nullable
@Override
public CharSequence getPageTitle(int position)
return fragmentTitle.get(position);
So if You are familiar with these kind of problem please help me..
*代码错误强>
error: cannot infer type arguments for ArrayAdapter<>
ArrayAdapter<String> adapter_one = new ArrayAdapter<>(
^
error: incompatible types: Apply cannot be converted to Context
dataPickerDialog_from = new DatePickerDialog(this, style, dataSetListener_from, year, month, day);
^
error: unreachable statement
SelectLeave = v.findViewById(txt_select_leave);
^
******************errors****************************
[enter image description here][3]
[enter image description here][4]
[1]: https://i.stack.imgur.com/hDZcQ.png
[2]: https://i.stack.imgur.com/sAVCB.png
[3]: https://i.stack.imgur.com/vbChu.png
[4]: https://i.stack.imgur.com/uuDg3.png
【问题讨论】：
“我使用的时候，出现了一些错误。我试过了，但我无法修复它。” - 请清楚地告诉我们和准确地这些错误是什么。 我想做这个斯蒂芬，只是我想将 apply.java 文件添加到我上面提到的片段之一。我可以把我的代码的图像？我可以告诉你... 没有。我们希望您提供错误消息、堆栈跟踪、任何 AS TEXT ...而不是屏幕截图或图像。 我认为java文件无法被android studio识别...... 注意：以上不是我不理解你。这完全是关于您根据堆栈溢出要求正确提出问题。 （希望......你学会了如何去做。） 【参考方案1】：这些是 Java 编译错误。
error: cannot infer type arguments for ArrayAdapter<>
ArrayAdapter<String> adapter_one = new ArrayAdapter<>(
Apply.this, R.layout.dropdown_item, Select_Leave
);
所以问题是ArrayAdapter 的所有构造函数都需要Context 作为第一个参数。但是你给了它一个Apply。 Apply 已被声明为 Fragment ... 而 Fragment 不是 Context。
error: incompatible types: Apply cannot be converted to Context
dataPickerDialog_from = new DatePickerDialog(
this, style, dataSetListener_from, year, month, day);
这几乎是相同的问题。 DatePickerDialog 构造函数都需要 Context 作为第一个参数，但 this 是 Apply 而不是 Context。
我对此不是 100% 确定，但我认为您应该在您的 Apply / Fragment 实例上调用 getContext() 并将结果传递给这两个构造函数...
请注意，您可以（并且应该）查找并阅读 Android 库类的 javadocs 以了解如何使用它们。例如，Fragment 的 javadocs 告诉您 Fragment 不是 Context ...但它确实有 getContext() 方法。
【讨论】：
好的，你能告诉我getContext()在代码中应用的地方吗？？？ 在第一个 ... 将Apply.this 更改为 Apply.this.getContext()。第二个你应该能够自己锻炼。
所以这些错误现在得到修复。但在 findviewbyid 部分设置了错误。我是复制并粘贴错误。我可以得到帮助吗？？
这是我要给你的最后帮助。 return 之后的任何语句都无法访问。查看给出该编译错误的行之前的行。修复很明显。以上是关于如何使用tablayout和片段管理java文件[关闭]的主要内容，如果未能解决你的问题，请参考以下文章
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