我该如何使用DialogFragment从MainActivity中获取TextView？

Question

我正在写一个简单的应用程序，它会打开一个时间选择器对话框，要求输入，对照系统时间检查它，并告诉您它是否正确。 但是，我需要获取显示是true还是false的TextView，并在作为DialogFragment的TimePickerFragment中进行更改。 我该怎么办？

TimePickerFragment.java

package com.example.timechecker;
import java.util.Calendar;

import android.app.Dialog;
import android.app.TimePickerDialog;
import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.text.format.DateFormat;
import android.widget.TimePicker;

public class TimePickerFragment extends DialogFragment
                        implements TimePickerDialog.OnTimeSetListener {
int hour;
int minutes;


@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    // Use the current time as the default values for the picker
    final Calendar c = Calendar.getInstance();
    hour = c.get(Calendar.HOUR_OF_DAY);
    minutes = c.get(Calendar.MINUTE);

    // Create a new instance of TimePickerDialog and return it
    return new TimePickerDialog(getActivity(), this, 12, 00,
            DateFormat.is24HourFormat(getActivity()));
}

public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

    //Grab the Text View from the Main Activity
//      MainActivity m = new MainActivity();
//      m.grabText text = new m.grabText();

    //Check if given Picker value is == to the system time, display whether or          not it is so
    if (hourOfDay == hour && minutes == minute) {
        text.setText("You are correct!");
    } else {
        text.setText("You are incorrect!");
    }
}
}

MainActivity.java

package com.example.timechecker;

import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.support.v4.app.FragmentActivity;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends FragmentActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}
//Creates the dialog with the Time Picker
public void checkTime(View view) {
    DialogFragment newFragment = new TimePickerFragment();
    newFragment.show(getSupportFragmentManager(), "timePicker");

}

//Class to grab the Text View for the Dialog Fragment
public class grabText {
    TextView text = (TextView) findViewById(R.id.whatTime);

    //Uses a method to set the Text View text
    public void setText(String string) {
        text.setText(string);
    }
}

}

Answer 1

当您在任何活动中调用findViewById时，我只会在活动布局中进行搜索。 因此，要从对话框中获取TextView，您需要对该对话框的引用，然后调用dialog.findViewById（id_of_field），这将为您提供所需的TextView。

希望这可以帮助

Answer 2

我最近做了这个，我可以通过将MainActivity.java设置为DialogFragment的父级来DialogFragment 。

MainActivity.Java

将此添加到MainActivity ：

@Override
protected void onCreate(Bundle savedInstanceState) {
    mActivity = this;

之后，将其设置为全局：

public class MainActivity extends Activity {
    MainActivity mActivity;

对话片段

将此添加到DialogFragment ：

public void setParent(MainActivity parent) {
    mParent = parent;
}

之后，将其设置为全局：

public class ClearDialogModern extends DialogFragment {
    MainActivity mParent;

编辑：在这里您setParent 。 将其放在您的MainActivity.java onCreate ：

newDialogFragment = new DialogFragment();
newDialogFragment.setParent(mActivity);

如何使用：

现在，您可以使用mParent引用MainActivity.java。