activity_example_app_widget_config.xmlExampleAppWidgetConfig.javaexample_widget.xmlExampleAppWidgetProvider.javaexample_appwidget_info.xmlAndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:gravity="center_horizontal"
    android:orientation="vertical"
    tools:context="com.codinginflow.widgetexample.ExampleAppWidgetConfig">

    <EditText
        android:id="@+id/edit_text_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:hint="Button text" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="confirmConfiguration"
        android:text="Confirm" />

</LinearLayout>

package com.codinginflow.widgetexample;

import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.RemoteViews;

public class ExampleAppWidgetConfig extends AppCompatActivity {
    public static final String SHARED_PREFS = "prefs";
    public static final String KEY_BUTTON_TEXT = "keyButtonText";

    private int appWidgetId = AppWidgetManager.INVALID_APPWIDGET_ID;
    private EditText editTextButton;

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

        Intent configIntent = getIntent();
        Bundle extras = configIntent.getExtras();
        if (extras != null) {
            appWidgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID,
                    AppWidgetManager.INVALID_APPWIDGET_ID);
        }

        Intent resultValue = new Intent();
        resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
        setResult(RESULT_CANCELED, resultValue);

        if (appWidgetId == AppWidgetManager.INVALID_APPWIDGET_ID) {
            finish();
        }

        editTextButton = findViewById(R.id.edit_text_button);
    }

    public void confirmConfiguration(View v) {
        AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(this);

        Intent intent = new Intent(this, MainActivity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);

        String buttonText = editTextButton.getText().toString();

        RemoteViews views = new RemoteViews(this.getPackageName(), R.layout.example_widget);
        views.setOnClickPendingIntent(R.id.example_widget_button, pendingIntent);
        views.setCharSequence(R.id.example_widget_button, "setText", buttonText);

        appWidgetManager.updateAppWidget(appWidgetId, views);

        SharedPreferences prefs = getSharedPreferences(SHARED_PREFS, MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putString(KEY_BUTTON_TEXT + appWidgetId, buttonText);
        editor.apply();

        Intent resultValue = new Intent();
        resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
        setResult(RESULT_OK, resultValue);
        finish();
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/example_widget_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="Press me" />

</RelativeLayout>

package com.codinginflow.widgetexample;

import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.widget.RemoteViews;

import static com.codinginflow.widgetexample.ExampleAppWidgetConfig.KEY_BUTTON_TEXT;
import static com.codinginflow.widgetexample.ExampleAppWidgetConfig.SHARED_PREFS;


public class ExampleAppWidgetProvider extends AppWidgetProvider {

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        for (int appWidgetId : appWidgetIds) {
            Intent intent = new Intent(context, MainActivity.class);
            PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);

            SharedPreferences prefs = context.getSharedPreferences(SHARED_PREFS, Context.MODE_PRIVATE);
            String buttonText = prefs.getString(KEY_BUTTON_TEXT + appWidgetId, "Press me");

            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.example_widget);
            views.setOnClickPendingIntent(R.id.example_widget_button, pendingIntent);
            views.setCharSequence(R.id.example_widget_button, "setText", buttonText);

            appWidgetManager.updateAppWidget(appWidgetId, views);
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:configure="com.codinginflow.widgetexample.ExampleAppWidgetConfig"
    android:initialLayout="@layout/example_widget"
    android:minHeight="40dp"
    android:minResizeWidth="40dp"
    android:minWidth="110dp"
    android:previewImage="@drawable/widget_preview"
    android:resizeMode="vertical|horizontal"
    android:updatePeriodMillis="3600000"
    android:widgetCategory="home_screen">

</appwidget-provider>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.codinginflow.widgetexample">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:launchMode="singleTop">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <receiver android:name=".ExampleAppWidgetProvider">
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
            </intent-filter>

            <meta-data
                android:name="android.appwidget.provider"
                android:resource="@xml/example_appwidget_info" />
        </receiver>

        <activity android:name=".ExampleAppWidgetConfig">
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_CONFIGURE" />
            </intent-filter>
        </activity>
    </application>

</manifest>