如何在Android的同一活動中將日期從一個片段傳遞到另一個片段？

Question

我在將數據（用戶從“日期”小部件中選擇的日期”）從小部件傳遞回調用片段並將其設置在“按鈕”上時遇到麻煩。 起始片段成功地將當前日期傳遞給窗口小部件，但是將用戶選擇的日期傳遞回調用片段時遇到麻煩。

這是開始片段的代碼，即CrimeFragment

package com.khalsa.gurankassingh.criminalintent;


import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.text.Editable;
import android.text.TextWatcher;
import android.text.format.DateFormat;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.EditText;

import java.util.Date;
import java.util.UUID;

/**
 * Created by Gurankas Singh on 3/12/2017.
 */

public class CrimeFragment extends Fragment
{
    public static final String ARG_CRIME_ID = "crime_id";
    public static final String DIALOG_DATE = "DialogDate";

private static final int REQUEST_DATE = 0;

private Crime mCrime;               //instance of the Crime class
private EditText mTitleField;       // The editable text field in the fragment
private Button mDateButton;         //Displays the date of the crime on the button
private CheckBox mSolvedCheckBox;   //Displays the current status of the crime; solved or unsolved

public static CrimeFragment newInstance(UUID crimeID)           //to pass value to the fragment via an arguement to another fragment
{
    Bundle args = new Bundle();
    args.putSerializable(ARG_CRIME_ID,crimeID);

    CrimeFragment fragment = new CrimeFragment();
    fragment.setArguments(args);
    return fragment;
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    UUID crimeId = (UUID)getArguments().getSerializable(ARG_CRIME_ID);
    mCrime = CrimeLab.get(getActivity()).getCrime(crimeId);

}

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState)
{
    View v = inflater.inflate(R.layout.fragment_crime,container,false);

    mTitleField = (EditText) v.findViewById(R.id.crime_title);
    mTitleField.setText(mCrime.getTitle());
    mTitleField.addTextChangedListener(new TextWatcher()
    {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after)
        {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count)
        {
            mCrime.setTitle(s.toString());
        }

        @Override
        public void afterTextChanged(Editable s)
        {

        }
    });

    mDateButton = (Button) v.findViewById(R.id.crime_date);
    updateDate();
    mDateButton.setOnClickListener(new View.OnClickListener()
    {

        @Override
        public void onClick(View v)
        {
            FragmentManager fragmentManager = getFragmentManager();
            DatePickerFragment dialog = DatePickerFragment.newInstance(mCrime.getDate());
            setTargetFragment(CrimeFragment.this,REQUEST_DATE);
            dialog.show(fragmentManager, DIALOG_DATE);
        }
    });

    mSolvedCheckBox = (CheckBox) v.findViewById(R.id.crime_solved);
    mSolvedCheckBox.setChecked(mCrime.isSolved());
    mSolvedCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener()
    {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked)
        {
            //set the crime's solved property
            mCrime.setSolved(isChecked);
        }
    });

    return v;
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data)
{
    if (resultCode != Activity.RESULT_OK)
    {
        return;
    }
    if (requestCode == REQUEST_DATE)
    {
        Date date = (Date)data.getSerializableExtra(DatePickerFragment.EXTRA_DATE);
        mCrime.setDate(date);
        updateDate();
    }
}

private void updateDate()
{
    mDateButton.setText(DateFormat.format("EEEE, d MMMM, yyy", mCrime.getDate()));
}
}

這是由DatePickerFragment托管的datePicker小部件的代碼

package com.khalsa.gurankassingh.criminalintent;

import android.app.Activity;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.DialogFragment;
import android.support.v7.app.AlertDialog;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.DatePicker;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

/**
 * Created by Gurankas Singh on 4/9/2017.
 */

public class DatePickerFragment extends DialogFragment
{
    private static final String DATE_ARG = "date";
public static final String EXTRA_DATE = "com.khalsa.gurankassingh.criminalintent.date";

private DatePicker mDatePicker;

public static DatePickerFragment newInstance(Date date)
{
    Bundle args = new Bundle();
    args.putSerializable(DATE_ARG,date);

    DatePickerFragment fragment = new DatePickerFragment();
    fragment.setArguments(args);
    return fragment;
}

@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState)
{
    Date date = (Date)getArguments().getSerializable(DATE_ARG);

    Calendar calendar = Calendar.getInstance();
    calendar.setTime(date);
    int year = calendar.get(Calendar.YEAR);
    int month = calendar.get(Calendar.MONTH);
    int day = calendar.get(Calendar.DAY_OF_MONTH);

    View v = LayoutInflater.from(getActivity()).inflate(R.layout.dialog_date,null);

    mDatePicker = (DatePicker)v.findViewById(R.id.dialog_date_date_picker);
    mDatePicker.init(year,month,day,null);

    return new AlertDialog.Builder(getActivity()).setView(v).setTitle(R.string.date_picker_title).setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener()
    {
        @Override
        public void onClick(DialogInterface dialog, int which)
        {
            int year = mDatePicker.getYear();
            int month = mDatePicker.getMonth();
            int day = mDatePicker.getDayOfMonth();
            Date date = new GregorianCalendar(year, month, day).getTime();
            sendResult(Activity.RESULT_OK, date);
        }
    }).create();
}
private void sendResult(int resultCode, Date date)
{
    if (getTargetFragment() == null)
    {
        return;
    }
    Intent intent = new Intent();
    intent.putExtra(EXTRA_DATE,date);

    getTargetFragment().onActivityResult(getTargetRequestCode(), resultCode, intent);
}

}

Answer 1

要在Fragments之間傳遞數據，您需要知道的是：

1-若要將數據從Activity傳遞到Fragment使用對象實例，在Activity創建Fragment ，您需要從其中獲得一個實例，因此可以使用它來傳遞數據，如下所示：

class Activity1 extend AppCompatActivity {

   Fragment1 fragment;

   void doSomethingInFramgent() {

      fragment.doSomething();
   }
}

2-要將數據從Fragment傳遞到Activity ，請使用Interface ，創建一個Interface並使用以下步驟：

2-1-創建一個Interface文件：

public interface FragmentInteraction {
     void doSomethingInActivity();
}

2-2-在Activity實現Interface ：

 class Activity1 extend AppCompatActivity implement FragmentInteraction {

    void doSomethingInActivity() {
       // do whatever you need
    }
 }

2-3-從Interface創建一個對象， onAttach像下面這樣在onAttach初始化它：

   class Fragment1 extend Fragment {

   FragmentInteraction fragmentInteraction;

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        if (context instanceof FragmentInteraction) {
            fragmentInteraction = (FragmentInteraction) context;
        }
    }

}

2-4-使用Interface實例在Activity調用方法，例如：

fragmentInteraction.doSomethinInActivity();

有了這個概念，您就可以在Fragments和Activity之間傳遞數據，例如，如果要將數據從一個片段傳遞到另一個Activity中的另一個片段，則可以：

活動1，片段1。 活動2，片段2

與通過數據Interface從Fragment1至Activity1 ，啟動Activity2與startActivityForResult ，通過與數據fragment2對象，具有返回數據Interface到Activity2然后使用setResult並返回到Activity1

PS：如果要在創建Fragment對象時傳遞數據，則可以使用Argument傳遞數據。

為此，您可以使用以下方法：

1-為獲取片段實例創建靜態方法：

 public static Fragment1 getInstance(String data1) {

        Fragment1 fragment = new Fragment1();

        Bundle bundle = new Bundle();
        bundle.putString(KEY, data1);
        fragment.setArguments(bundle);

        return fragment;
    }

然后在onCreateView上onViewCreate讓您的數據，如：

 if (getArguments() != null) {
     data = getArguments().getString(KEY);    
 }

Answer 2

您可以嘗試以下解決方案：-

=>更改CrimeFragment中的以下代碼

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data)
{
    if (resultCode != Activity.RESULT_OK)
    {
        return;
    }
    if (requestCode == REQUEST_DATE)
    {
        long dateValue = data.getLongExtra(DatePickerFragment.EXTRA_DATE,System.currentTimeMillis());
        Date date = new Date(dateValue);
        mCrime.setDate(date);
        updateDate();
    }
}

並在DatePickerFragment中更改以下代碼：-

private void sendResult(int resultCode, Date date)
        {
            if (getTargetFragment() == null)
            {
                return;
            }
            Intent intent = new Intent();
            intent.putExtra(EXTRA_DATE, date.getTime());

            getTargetFragment().onActivityResult(getTargetRequestCode(), resultCode, intent);
        }

....

Answer 3

您好，嘗試這種方法，

您可以使用共享首選項存儲日期，以后可以在需要時訪問它，這很容易處理。請記住日期格式，並相應地選擇SimpleDateFormat，因為如果輸入日期的格式不正確，則會出現解析錯誤相同。

寫入共享首選項

SharedPreferences sharedpreferences;
sharedpreferences = getSharedPreferences("myPref", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedpreferences.edit();
            editor.putString("Date",String.valueOf(date);
            editor.commit();

必要時閱讀SharedPreferences

SharedPreferences prefs = this.getSharedPreferences("myPref", Context.MODE_PRIVATE);
String dateCrime = prefs.getString("Date", null);  

//Chose Date format depending on your date
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");  
try {  
    Date date = format.parse(dateCrime);   
} catch (ParseException e) {    
    e.printStackTrace();  
}