[JAVA] Android Development-Try to display a dialog-

Introduction

Hello. I'm Wataku, a server-side programmer who is studying programming at a certain school. : relaxed: Let's develop Android this time as well.

Target person

--A person who can write Java somehow. --Someone who is ambiguous in Android development but can do it a little.

Display dialog

Dialog configuration

public class SimpleDialogFragment  extends DialogFragment {

** 2) Describe the dialog body generation process in the onCreateDialog () method. ** **

public Dialog onCreateDialog( ... ) { 
Dialog generation process(See below)
}

** 3) Write the following code when displaying a dialog for activities etc. **

--New the above class.

SimpleDialogFragment dialog = new SimpleDialogFragment();

--Get Fragment Manager.

FragmentManager manager = getSupportedFragmentManager();

--Display the dialog with the show () method.

<The following two arguments.>
1st:Fragment manager
No. 2:Tag string that identifies the dialog(Arbitrary string)
dialog . show ( manager , “ ... ” );

(note) Both DialogFragment.FragmentManager import the v4 package.

○ import android.support.v4.app.FragmentManager 

× import android.app.FragmentManager

Dialog body generation procedure

Follow the procedure below to generate the error dialog body described in the onCreateDialog () method of the dialog fragment class you created.

** 1) Create an alert dialog builder object. ** **

AlertDialog.Builder builder = new AlertDialog.Builder(context);

** 2) Set the display contents. ** **

・ Content area
builder.setMessage( ... );
·title
builder.setTitle( ... );

** 3) Set the action button. ** **

builder . setPositiveButton(“Button label”,Listener object when the button is tapped(See below)); 

There are also * setNegativeButton () * and * setNeutralButton () *.

** 4) Create a dialog object. ** **

AlertDialog dialog = builder.create( ) ;

(note) ʻThe AlertDialog class imports from the v7 package `

Click processing

The process when the action button is tapped in the alert dialog is described in the listener class. The procedure is as follows. ** 1) Create a nested class that implements the DialogInterface.OnClickListener interface. ** **

** 2) Describe the process in the onClick () method. ** **

private class DialogButtonClickListener implements DialogInterface.OnClickListener {
        @Override
        public void onClick(DialogInterface dialog (dialog body),int which (constant value of tapped button)) {
            //Click processing
        }
}

(note) If there are multiple action buttons, a listener class may be prepared for each button, but it may be branched using the second argument (int which).

Cooperation with activities

** (1) Get activity **

To get the activity that the dialog body is displayed in the dialog fragment, use the ** getActivity () ** method.

Activity parent = getActivity();

** (2) Data I **

To pass data from an activity to a dialog fragment, use the following method. ** 1) Create a Bundle object. ** **

Bundle extras = new Bundle();

** 2) Describe the process in the onClick () method. ** **

extends.put data type("name",value);

** 3) Set the Bundle object of 2) in the dialog fragment object. ** **

dialog.setArgments(extends);

** 4) In the dialog fragment, get the above Bundle object with the getArgments () method and retrieve the data. → The extraction method is the same as for Intent (null check in advance) **

Sample code

FullDialogFragment.java

public class FullDialogFragment extends DialogFragment {
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        builder.setTitle("Normal dialog");
        builder.setMessage("Is it OK?");
        builder.setPositiveButton("ok", new DialogButtonClickListener());
        builder.setNeutralButton("??", new DialogButtonClickListener());
        builder.setNegativeButton("NG", new DialogButtonClickListener());
        AlertDialog dialog = builder.create();
        return dialog;
    }

    /**
     *A member class that describes what happens when a dialog button is pressed.
     */
    private class DialogButtonClickListener implements DialogInterface.OnClickListener {

        @Override
        public void onClick(DialogInterface dialog, int which) {
            Activity parent = getActivity();
            String msg = "";
            switch (which) {
                case DialogInterface.BUTTON_POSITIVE:
                    msg = "Normal dialog:OK is selected.";
                    break;
                case DialogInterface.BUTTON_NEUTRAL:
                    msg = "Normal dialog: ??Was selected.";
                    break;
                case DialogInterface.BUTTON_NEGATIVE:
                    msg = "Normal dialog:NG has been selected.";
                    break;
            }
            Toast.makeText(parent, msg, Toast.LENGTH_SHORT).show();
        }
    }
}

Activity class (excerpt)

FullDialogFragment dialog = new FullDialogFragment(); 
FragmentManager manager = getSupportFragmentManager();
dialog.show(manager,"FullDialogFragment");

TIPS

Date selection dialog

For the date selection dialog, "new" ** DatePickerDialog ** and ** show () **. The arguments are as follows.

-① Context -② Listener object -③ Initial value "year" -④ Initial value "month" → Java "month" starts * 0 * internally. -⑤ Initial value "day"

The listener object * implements * the ** DatePickerDialog.OnDateSetListener ** interface and describes the process in the ** onDateSet () ** method. The arguments are as follows.

-① Date specification screen parts -② Selected "year" -③ Selected "month" -④ Selected "day"

Sample code

public void showDatePickerDialog(View view){
        Calendar cal = Calendar.getInstance();
        int nowYear = cal.get(Calendar.YEAR);
        int nowMonth = cal.get(Calendar.MONTH);
        int nowDayOfMonth = cal.get(Calendar.DAY_OF_MONTH);

        DatePickerDialog dialog = new DatePickerDialog(DialogSampleActivity.this, new DatePickerDialogDateSetListener(),nowYear,nowMonth,nowDayOfMonth);
        dialog.show();
}

private class DatePickerDialogDateSetListener implements DatePickerDialog.OnDateSetListener {

        @Override
        public void onDateSet(DatePicker view,int year,int month,int dayOfMonth) {
            String msg = "Date selection dialog:" + year + "Year" + (month + 1) + "Month" + dayOfMonth + "Day";
            Toast.makeText(DialogSampleActivity.this, msg, Toast.LENGTH_SHORT).show();
        }
}

Time selection dialog

For the time selection dialog, "new" ** TimePickerDialog ** and ** show () **. The arguments are as follows.

-① Context -② Listener object -③ Initial value "hour" (24-hour unit) -④ Initial value "minute" -⑤ Whether to display 24 hours (true is 24 hours notation)

The listener object * implements * the ** TimePickerDialog.OnTimeSetListener ** interface and describes the process in the ** onTimeSet () ** method. The arguments are as follows.

-① Time specification screen parts -② Selected "time" --③ Selected "minutes"

Sample code

public void showTimePickerDialog(View view){
        TimePickerDialog dialog = new TimePickerDialog(DialogSampleActivity.this, new TimePickerDialogTimeSetListener(),0,0,true );
        dialog.show();
}

private class TimePickerDialogTimeSetListener implements TimePickerDialog.OnTimeSetListener {

        @Override
        public void onTimeSet(TimePicker view,int hourOfDay,int minute) {
            String msg = "Time selection dialog:" + hourOfDay + "Time" + minute + "Minutes";
            Toast.makeText(DialogSampleActivity.this, msg, Toast.LENGTH_SHORT).show();
        }
}

that's all. It was how to display the dialog on Android. If you have any suggestions such as something wrong, please contact us. Thank you for reading to the end.