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Die Anleitung zu Android DialogFragment

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1- Android DialogFragment

Android DialogFragment ist ein Fragment, das einen Dialog enthält. Es steuert den Betrieb des Dialog, z.B es legt fest, wann dieses Dialog ausgeblendet, angezeigt oder geschlossen werden soll. Sie sollten mit dem Dialog über die Methoden von DialogFragment interagieren, anstatt direkt zu interagieren.
Sie können die Frage stellen: "Warum brauchen wir DialogFragment wenn wir bereits einen Dialog haben?". Die Antwort lautet: DialogFragment wurde erstellt, um einige der Schwächen von Dialog zu überwinden.
  • TODO

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Es ist sehr leicht für Sie, ein DialogFragment zu erhalten. Führen Sie einfach zwei Schritte wie folgt durch:
Schreiben Sie eine Klasse von YourDialogFragment, die aus der Klasse DialogFragment erweitert wurde. Überschreiben Sie dann die Methode onCreateDialog(Bundle), die einen Dialog (YourDialog) zurückgibt.Deshalb spielt YourDialogFragment jetzt die Rolle eines Containers von YourDialog.
Android DialogFragment Javadocs:

2- Das Beispiel von DialogFragment

In diesem Beispiel werden wir die Klasse YesNoDialogFragment erstellen, die aus der Klasse DialogFragment erweitert wurde. Diese Klasse enthält ein AlertDialog mit 2 Buttons: YES/NO.
Dieses Beispiel zeigt, wie Sie YesNoDialogFragment aus einer Activity erstellen und anzeigen. Sie können YesNoDialogFragment aus einem anderen Fragment mit einer kleinen Änderung im Code erstellen und anzeigen.
OK, Auf Android Studio erstellen Sie ein Projekt:
  • File > New > New Project > Empty Activity
    • Name: DialogFragmentExample
    • Package name: org.o7planning.dialogfragmentexample
    • Language: Java
Die Interface der Anwendung sieht aus:
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button_show"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="Show Dialog Fragment"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="24dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:gravity="center"
        android:text="---"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button_show" />
</androidx.constraintlayout.widget.ConstraintLayout>
YesNoDialogFragment.java
package org.o7planning.dialogfragmentexample;

import android.app.Activity;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;
import androidx.fragment.app.DialogFragment;

public class YesNoDialogFragment extends DialogFragment {

    public static final String ARG_TITLE = "YesNoDialog.Title";
    public static final String ARG_MESSAGE = "YesNoDialog.Message";

    private YesNoDialogFragmentListener listener;

    public interface YesNoDialogFragmentListener {
        /**
         *
         * @param resultCode - Activity.RESULT_OK, Activity.RESULT_CANCEL
         * @param data
         */
         public void onYesNoResultDialog(int resultCode, @Nullable Intent data);
    }

    public YesNoDialogFragment() {

    }

    public void setOnYesNoDialogFragmentListener(YesNoDialogFragmentListener listener) {
        this.listener = listener;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        Bundle args = getArguments();
        String title = args.getString(ARG_TITLE);
        String message = args.getString(ARG_MESSAGE);

        return new AlertDialog.Builder(getActivity())
                .setTitle(title)
                .setMessage(message)
                .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        buttonOkClick();
                    }
                })
                .setNegativeButton("No", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        buttonNoClick();
                    }
                })
                .create();
    }

    private void buttonOkClick() {
        int resultCode = Activity.RESULT_OK;

        Bundle bundle = new Bundle();
        bundle.putString("key1", "Value 1");
        bundle.putString("key2", "Value 2");
        Intent data  = new Intent().putExtras(bundle);

        // Open this DialogFragment from an Activity.
        if(this.listener != null)  {
            this.listener.onYesNoResultDialog(Activity.RESULT_OK, data);
        }
        // Open this DialogFragment from another Fragment.
        else {
            // Send result to your TargetFragment.
            // See (Your) TargetFragment.onActivityResult()
            getTargetFragment().onActivityResult(getTargetRequestCode(), resultCode, data);
        }
    }

    private void buttonNoClick() {
        int resultCode = Activity.RESULT_CANCELED;
        Intent data  = null;

         // Open this DialogFragment from an Activity.
        if(this.listener != null)  {
            this.listener.onYesNoResultDialog(resultCode, data);
        }
        // Open this DialogFragment from another Fragment.
        else {
            // Send result to your TargetFragment.
            // See (Your) TargetFragment.onActivityResult()
            getTargetFragment().onActivityResult(getTargetRequestCode(), resultCode, data);
        }
    }

}
MainActivity.java
package org.o7planning.dialogfragmentexample;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.DialogFragment;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity
        implements YesNoDialogFragment.YesNoDialogFragmentListener {

    private Button buttonShow;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        this.buttonShow = (Button) this.findViewById(R.id.button_show);
        this.textView = (TextView) this.findViewById(R.id.textView);

        this.buttonShow.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                buttonShowClicked();
            }
        });
    }

    // User click on "Show Dialog" button.
    private void buttonShowClicked()  {
        this.textView.setText("---");

        // Create YesNoDialogFragment
        DialogFragment dialogFragment = new YesNoDialogFragment();

        // Arguments:
        Bundle args = new Bundle();
        args.putString(YesNoDialogFragment.ARG_TITLE, "Confirmation");
        args.putString(YesNoDialogFragment.ARG_MESSAGE, "Do you like this example?");
        dialogFragment.setArguments(args);

        FragmentManager fragmentManager = this.getSupportFragmentManager();

        // Show:
        dialogFragment.show(fragmentManager, "Dialog");
    }

    @Override
    public void onAttachFragment(Fragment fragment) {
        if (fragment instanceof YesNoDialogFragment) {
            YesNoDialogFragment yesNoDialogFragment = (YesNoDialogFragment) fragment;
            yesNoDialogFragment.setOnYesNoDialogFragmentListener(this);
        }
    }

    // Implement method of YesNoDialogFragment.YesNoDialogFragmentListener
    @Override
    public void onYesNoResultDialog(int resultCode, @Nullable Intent data) {
        if(resultCode == Activity.RESULT_OK) {
            String value1 = data.getStringExtra("key1"); // ...
            this.textView.setText("You select YES");
        } else if(resultCode == Activity.RESULT_CANCELED) {
            this.textView.setText("You select NO");
        } else {
            this.textView.setText("You don't select");
        }
    }

}
Unten ist die Code zur Erstellung und Anzeigen vom YesNoDialogFragment aus einem anderen Fragment.
ExampleFragment.java
package org.o7planning.dialogfragmentexample;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;

import androidx.annotation.Nullable;
import androidx.fragment.app.DialogFragment;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

public class ExampleFragment extends Fragment {

    private static final int REQUEST_CODE_YESNO_DIALOG_FRAGMENT = 1000;
    
    public ExampleFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_example, container, false);
    }

    // Call this method to show YesNoDialogFragment
    private void showYesNoDialogFragment() {
        // Create YesNoDialogFragment
        DialogFragment dialogFragment = new YesNoDialogFragment();

        // Arguments:
        Bundle args = new Bundle();
        args.putString(YesNoDialogFragment.ARG_TITLE, "Confirmation");
        args.putString(YesNoDialogFragment.ARG_MESSAGE, "Do you like this example?");
        dialogFragment.setArguments(args);

        // YesNoDialogFragment will return results for targetFragment.
        // So, Need to Override onActivityResult() method, to get results.
        Fragment targetFragment = this;

        // IMPORTANT!!
        dialogFragment.setTargetFragment(targetFragment, REQUEST_CODE_YESNO_DIALOG_FRAGMENT);

        FragmentManager fragmentManager = this.getFragmentManager();
        // Show:
        dialogFragment.show(fragmentManager, "Dialog");
    }

    // Results are returned by YesNoDialogFragment.
    @Override
    public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == REQUEST_CODE_YESNO_DIALOG_FRAGMENT) {
            if(resultCode == Activity.RESULT_OK) {
                Toast.makeText(this.getContext(), "You select YES", Toast.LENGTH_LONG).show();
            } else if(resultCode == Activity.RESULT_CANCELED) {
                Toast.makeText(this.getContext(), "You select NO", Toast.LENGTH_LONG).show();
            }
        }
    }
}

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