Added missing files for previous commit

src/main/java/com/nutomic/syncthingandroid/activities/FirstStartActivity.java

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+package com.nutomic.syncthingandroid.activities;
+
+import android.Manifest;
+import android.app.Activity;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.content.pm.PackageManager;
+import android.os.Bundle;
+import android.preference.PreferenceManager;
+import android.support.annotation.NonNull;
+import android.support.v4.app.ActivityCompat;
+import android.support.v4.content.ContextCompat;
+import android.view.View;
+import android.widget.Button;
+import android.widget.Toast;
+import com.nutomic.syncthingandroid.R;
+
+public class FirstStartActivity extends Activity implements Button.OnClickListener {
+
+    private static final String TAG = "FirstStartActivity";
+
+    private static final int REQUEST_WRITE_STORAGE = 142;
+
+    private SharedPreferences mPreferences;
+
+    /**
+     * Handles activity behaviour depending on {@link #isFirstStart()} and {@link #haveStoragePermission()}.
+     */
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_first_start);
+
+        mPreferences = PreferenceManager.getDefaultSharedPreferences(this);
+        Button cont = (Button) findViewById(R.id.cont);
+        cont.setOnClickListener(this);
+
+        if (!isFirstStart()) {
+            if (haveStoragePermission()) {
+                startApp();
+            }
+            else {
+                requestStoragePermission();
+            }
+        }
+    }
+
+    private boolean isFirstStart() {
+        return mPreferences.getBoolean("first_start", true);
+    }
+
+    private void startApp() {
+        boolean isFirstStart = isFirstStart();
+        if (isFirstStart) {
+            mPreferences.edit().putBoolean("first_start", false).apply();
+        }
+        Intent intent = new Intent(this, MainActivity.class);
+        intent.putExtra(MainActivity.EXTRA_FIRST_START, isFirstStart);
+        startActivity(intent);
+        finish();
+
+    }
+
+    private boolean haveStoragePermission() {
+        int permissionState = ContextCompat.checkSelfPermission(this,
+                Manifest.permission.WRITE_EXTERNAL_STORAGE);
+        return permissionState == PackageManager.PERMISSION_GRANTED;
+    }
+
+    private void requestStoragePermission() {
+        ActivityCompat.requestPermissions(this,
+                new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
+                REQUEST_WRITE_STORAGE);
+    }
+
+    @Override
+    public void onClick(View v) {
+        if (!haveStoragePermission()) {
+            requestStoragePermission();
+        }
+        else {
+            startApp();
+        }
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
+                                           @NonNull int[] grantResults) {
+        switch (requestCode) {
+            case REQUEST_WRITE_STORAGE:
+                if (grantResults.length == 0 ||
+                        grantResults[0] != PackageManager.PERMISSION_GRANTED) {
+                    Toast.makeText(this, R.string.toast_write_storage_permission_required,
+                            Toast.LENGTH_LONG).show();
+                } else {
+                    startApp();
+                }
+                break;
+            default:
+                super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+        }
+    }
+
+}

src/main/res/layout/activity_first_start.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout
+        xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:padding="16dp"
+        tools:context="com.nutomic.syncthingandroid.activities.FirstStartActivity">
+
+    <TextView
+            android:id="@+id/title"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/welcome_title"
+            android:layout_centerHorizontal="true"
+            android:gravity="center"
+            android:textColor="@color/primary_dark"
+            android:textSize="30sp"
+            android:layout_margin="30dp" />
+
+    <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/welcome_text"
+            android:layout_below="@id/title"
+            android:textSize="16sp"
+            android:lineSpacingExtra="5sp"
+            android:layout_marginStart="30dp"
+            android:layout_marginLeft="30dp"
+            android:layout_marginEnd="30dp"
+            android:layout_marginRight="30dp" />
+
+    <Button
+            android:id="@+id/cont"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/cont"
+            android:background="?android:selectableItemBackground"
+            android:textColor="@color/accent"
+            android:layout_alignParentEnd="true"
+            android:layout_alignParentRight="true"
+            android:layout_alignParentBottom="true"/>
+
+</RelativeLayout>