Add a button to change the backup storage location

app/src/main/java/com/stevesoltys/backup/activity/MainActivity.java

@@ -5,26 +5,46 @@ import android.content.Intent;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
+import android.widget.Button;
 
 import com.stevesoltys.backup.R;
 
+import static android.view.View.GONE;
+import static android.view.View.VISIBLE;
+
 public class MainActivity extends Activity implements View.OnClickListener {
 
     public static final int OPEN_DOCUMENT_TREE_REQUEST_CODE = 1;
 
-    public static final int LOAD_DOCUMENT_REQUEST_CODE = 2;
+    public static final int OPEN_DOCUMENT_TREE_BACKUP_REQUEST_CODE = 2;
+
+    public static final int LOAD_DOCUMENT_REQUEST_CODE = 3;
 
     private MainActivityController controller;
+    private Button changeLocationButton;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
 
+        controller = new MainActivityController();
+
         findViewById(R.id.create_backup_button).setOnClickListener(this);
         findViewById(R.id.restore_backup_button).setOnClickListener(this);
 
-        controller = new MainActivityController();
+        changeLocationButton = findViewById(R.id.change_backup_location_button);
+        changeLocationButton.setOnClickListener(this);
+    }
+
+    @Override
+    protected void onStart() {
+        super.onStart();
+        if (controller.isChangeBackupLocationButtonVisible(this)) {
+            changeLocationButton.setVisibility(VISIBLE);
+        } else {
+            changeLocationButton.setVisibility(GONE);
+        }
     }
 
     @Override
@@ -40,6 +60,10 @@ public class MainActivity extends Activity implements View.OnClickListener {
             case R.id.restore_backup_button:
                 controller.showLoadDocumentActivity(this);
                 break;
+
+            case R.id.change_backup_location_button:
+                controller.onChangeBackupLocationButtonClicked(this);
+                break;
         }
     }
 
@@ -54,7 +78,11 @@ public class MainActivity extends Activity implements View.OnClickListener {
         switch (requestCode) {
 
             case OPEN_DOCUMENT_TREE_REQUEST_CODE:
-                controller.handleChooseFolderResult(result, this);
+                controller.handleChooseFolderResult(result, this, false);
+                break;
+
+            case OPEN_DOCUMENT_TREE_BACKUP_REQUEST_CODE:
+                controller.handleChooseFolderResult(result, this, true);
                 break;
 
             case LOAD_DOCUMENT_REQUEST_CODE:

app/src/main/java/com/stevesoltys/backup/activity/MainActivityController.java

@@ -24,6 +24,7 @@ import static android.content.Intent.FLAG_GRANT_WRITE_URI_PERMISSION;
 import static android.provider.DocumentsContract.buildDocumentUriUsingTree;
 import static android.provider.DocumentsContract.createDocument;
 import static android.provider.DocumentsContract.getTreeDocumentId;
+import static com.stevesoltys.backup.activity.MainActivity.OPEN_DOCUMENT_TREE_BACKUP_REQUEST_CODE;
 import static com.stevesoltys.backup.activity.MainActivity.OPEN_DOCUMENT_TREE_REQUEST_CODE;
 import static com.stevesoltys.backup.settings.SettingsManager.getBackupFolderUri;
 import static com.stevesoltys.backup.settings.SettingsManager.setBackupFolderUri;
@@ -40,26 +41,32 @@ class MainActivityController {
     void onBackupButtonClicked(Activity parent) {
         Uri folderUri = getBackupFolderUri(parent);
         if (folderUri == null) {
-            showChooseFolderActivity(parent);
+            showChooseFolderActivity(parent, true);
         } else {
             try {
                 Uri fileUri = createBackupFile(parent.getContentResolver(), folderUri);
                 showCreateBackupActivity(parent, fileUri);
+
             } catch (IOException e) {
                 e.printStackTrace();
-                showChooseFolderActivity(parent);
+                showChooseFolderActivity(parent, true);
             }
         }
     }
 
-    private void showChooseFolderActivity(Activity parent) {
+    boolean isChangeBackupLocationButtonVisible(Activity parent) {
-        Intent createDocumentIntent = new Intent(ACTION_OPEN_DOCUMENT_TREE);
+        return getBackupFolderUri(parent) != null;
-        createDocumentIntent.addFlags(FLAG_GRANT_PERSISTABLE_URI_PERMISSION |
+    }
+
+    private void showChooseFolderActivity(Activity parent, boolean continueToBackup) {
+        Intent openTreeIntent = new Intent(ACTION_OPEN_DOCUMENT_TREE);
+        openTreeIntent.addFlags(FLAG_GRANT_PERSISTABLE_URI_PERMISSION |
                 FLAG_GRANT_READ_URI_PERMISSION | FLAG_GRANT_WRITE_URI_PERMISSION);
 
         try {
-            Intent documentChooser = Intent.createChooser(createDocumentIntent, "Select the backup location");
+            Intent documentChooser = Intent.createChooser(openTreeIntent, "Select the backup location");
-            parent.startActivityForResult(documentChooser, OPEN_DOCUMENT_TREE_REQUEST_CODE);
+            int requestCode = continueToBackup ? OPEN_DOCUMENT_TREE_BACKUP_REQUEST_CODE : OPEN_DOCUMENT_TREE_REQUEST_CODE;
+            parent.startActivityForResult(documentChooser, requestCode);
 
         } catch (ActivityNotFoundException ex) {
             Toast.makeText(parent, "Please install a file manager.", Toast.LENGTH_SHORT).show();
@@ -80,7 +87,11 @@ class MainActivityController {
         }
     }
 
-    void handleChooseFolderResult(Intent result, Activity parent) {
+    void onChangeBackupLocationButtonClicked(Activity parent) {
+        showChooseFolderActivity(parent, false);
+    }
+
+    void handleChooseFolderResult(Intent result, Activity parent, boolean continueToBackup) {
 
         if (result == null || result.getData() == null) {
             return;
@@ -97,18 +108,19 @@ class MainActivityController {
         // store backup folder location in settings
         setBackupFolderUri(parent, folderUri);
 
-        // create a new backup file in folder
+        if (!continueToBackup) return;
-        Uri fileUri;
+
         try {
-            fileUri = createBackupFile(contentResolver, folderUri);
+            // create a new backup file in folder
+            Uri fileUri = createBackupFile(contentResolver, folderUri);
+
+            showCreateBackupActivity(parent, fileUri);
+
         } catch (IOException e) {
             // TODO show better error message once more infrastructure is in place
             Toast.makeText(parent, "Error creating backup file", Toast.LENGTH_SHORT).show();
             e.printStackTrace();
-            return;
         }
-
-        showCreateBackupActivity(parent, fileUri);
     }
 
     private void showCreateBackupActivity(Activity parent, Uri fileUri) {
@@ -134,6 +146,7 @@ class MainActivityController {
             Uri fileUri = createDocument(contentResolver, documentUri, DOCUMENT_MIME_TYPE, getBackupFileName());
             if (fileUri == null) throw new IOException();
             return fileUri;
+
         } catch (SecurityException e) {
             // happens when folder was deleted and thus Uri permission don't exist anymore
             throw new IOException(e);

app/src/main/res/layout/activity_main.xml

@@ -1,29 +1,37 @@
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-              xmlns:tools="http://schemas.android.com/tools"
+    xmlns:tools="http://schemas.android.com/tools"
-              android:id="@+id/activity_main"
+    android:id="@+id/activity_main"
-              android:layout_width="match_parent"
+    android:layout_width="match_parent"
-              android:layout_height="match_parent"
+    android:layout_height="match_parent"
-              android:orientation="vertical"
+    android:orientation="vertical"
-              android:weightSum="1"
+    tools:context="com.stevesoltys.backup.activity.MainActivity">
-              tools:context="com.stevesoltys.backup.activity.MainActivity">
 
     <Button
         android:id="@+id/create_backup_button"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginLeft="@dimen/button_horizontal_margin"
-        android:layout_marginRight="@dimen/button_horizontal_margin"
         android:layout_marginTop="@dimen/button_vertical_margin"
-        android:text="@string/create_backup_button"/>
+        android:layout_marginRight="@dimen/button_horizontal_margin"
+        android:text="@string/create_backup_button" />
 
     <Button
         android:id="@+id/restore_backup_button"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginLeft="@dimen/button_horizontal_margin"
-        android:layout_marginRight="@dimen/button_horizontal_margin"
         android:layout_marginTop="@dimen/button_vertical_margin"
-        android:text="@string/restore_backup_button"/>
+        android:layout_marginRight="@dimen/button_horizontal_margin"
+        android:text="@string/restore_backup_button" />
+
+    <Button
+        android:id="@+id/change_backup_location_button"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginLeft="@dimen/button_horizontal_margin"
+        android:layout_marginTop="72dp"
+        android:layout_marginRight="@dimen/button_horizontal_margin"
+        android:text="@string/change_backup_location_button" />
 
 </LinearLayout>

app/src/main/res/values/strings.xml

@@ -3,6 +3,7 @@
 
     <string name="create_backup_button">Create backup</string>
     <string name="restore_backup_button">Restore backup</string>
+    <string name="change_backup_location_button">Change backup location</string>
 
     <string name="backup_success">Backup success</string>
     <string name="backup_failure">Backup failure</string>