handle onBackPressed() in Fragment

library/src/main/java/com/nononsenseapps/filepicker/FilePickerActivity.java

@@ -8,13 +8,19 @@ package com.nononsenseapps.filepicker;
 
 import android.annotation.SuppressLint;
 import android.os.Environment;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 
 import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
 
 @SuppressLint("Registered")
 public class FilePickerActivity extends AbstractFilePickerActivity<File> {
 
+    @NonNull
+    private final List<OnBackPressedListener> onBackPressedListeners = new ArrayList<>();
+
     public FilePickerActivity() {
         super();
     }
@@ -30,4 +36,39 @@ public class FilePickerActivity extends AbstractFilePickerActivity<File> {
                 mode, allowMultiple, allowCreateDir, allowExistingFile, singleClick);
         return fragment;
     }
+
+    public void addOnBackPressedListener(@NonNull final OnBackPressedListener onBackPressedListener) {
+        onBackPressedListeners.add(onBackPressedListener);
+    }
+
+    public void removeOnBackPressedListener(@NonNull final OnBackPressedListener onBackPressedListener) {
+        onBackPressedListeners.remove(onBackPressedListener);
+    }
+
+    @Override
+    public void onBackPressed() {
+        for (final OnBackPressedListener onBackPressedListener : onBackPressedListeners) {
+            if (onBackPressedListener.onBackPressed()) {
+                return;
+            }
+        }
+
+        if (getSupportFragmentManager().getBackStackEntryCount() <= 1) {
+            supportFinishAfterTransition();
+        } else {
+            getSupportFragmentManager().popBackStack();
+        }
+    }
+
+    public interface OnBackPressedListener {
+
+        /**
+         * Calls when user presses device back button.
+         *
+         * @return True if it is processed by this object.
+         */
+        boolean onBackPressed();
+
+    }
+
 }

library/src/main/java/com/nononsenseapps/filepicker/FilePickerFragment.java

@@ -9,6 +9,7 @@ package com.nononsenseapps.filepicker;
 import android.Manifest;
 import android.content.pm.PackageManager;
 import android.net.Uri;
+import android.os.Bundle;
 import android.os.FileObserver;
 import android.support.annotation.NonNull;
 import android.support.v4.content.AsyncTaskLoader;
@@ -24,7 +25,7 @@ import java.io.File;
  * An implementation of the picker which allows you to select a file from the internal/external
  * storage (SD-card) on a device.
  */
-public class FilePickerFragment extends AbstractFilePickerFragment<File> {
+public class FilePickerFragment extends AbstractFilePickerFragment<File> implements FilePickerActivity.OnBackPressedListener {
 
     private static final String[] extensions = new String[]{".doc", ".docx", ".xlsx", ".xls", ".png", ".jpg", ".tif", ".pdf", ".jpeg"};
 
@@ -35,6 +36,12 @@ public class FilePickerFragment extends AbstractFilePickerFragment<File> {
     public FilePickerFragment() {
     }
 
+    @Override
+    public void onCreate(final Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        ((FilePickerActivity) getActivity()).addOnBackPressedListener(this);
+    }
+
     /**
      * This method is used to dictate whether hidden files and folders should be shown or not
      *
@@ -367,4 +374,21 @@ public class FilePickerFragment extends AbstractFilePickerFragment<File> {
             return lhs.getName().compareToIgnoreCase(rhs.getName());
         }
     }
+
+    @Override
+    public boolean onBackPressed() {
+        if ("/".equals(mCurrentPath.toString())) {
+            return false;
+        } else {
+            goUp();
+            return true;
+        }
+    }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        ((FilePickerActivity) getActivity()).removeOnBackPressedListener(this);
+    }
+
 }