Prefer AppCompat classes

AppCompat is the preferred way to go for any app targetting
a wider range of SDKs.

Replace all activities and fragments with their AppCompat
variants and fixup method calls to use support variants.

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

app/src/main/java/com/wireguard/android/activity/BaseActivity.java

@@ -1,10 +1,10 @@
 package com.wireguard.android.activity;
 
-import android.app.Activity;
 import android.content.Intent;
 import android.databinding.CallbackRegistry;
 import android.databinding.CallbackRegistry.NotifierCallback;
 import android.os.Bundle;
+import android.support.v7.app.AppCompatActivity;
 
 import com.wireguard.android.Application;
 import com.wireguard.android.backend.GoBackend;
@@ -17,7 +17,7 @@ import java.util.Objects;
  * Base class for activities that need to remember the currently-selected tunnel.
  */
 
-public abstract class BaseActivity extends Activity {
+public abstract class BaseActivity extends AppCompatActivity {
     private static final String KEY_SELECTED_TUNNEL = "selected_tunnel";
 
     private final SelectionChangeRegistry selectionChangeRegistry = new SelectionChangeRegistry();

app/src/main/java/com/wireguard/android/activity/MainActivity.java

@@ -1,9 +1,10 @@
 package com.wireguard.android.activity;
 
-import android.app.Fragment;
-import android.app.FragmentTransaction;
 import android.content.Intent;
 import android.os.Bundle;
+import android.support.v4.app.Fragment;
+import android.support.v4.app.FragmentManager;
+import android.support.v4.app.FragmentTransaction;
 import android.util.Log;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -28,6 +29,7 @@ public class MainActivity extends BaseActivity {
     private State state = State.EMPTY;
 
     private boolean moveToState(final State nextState) {
+        final FragmentManager fragmentManager = getSupportFragmentManager();
         Log.i(TAG, "Moving from " + state.name() + " to " + nextState.name());
         if (nextState == state) {
             return false;
@@ -37,16 +39,16 @@ public class MainActivity extends BaseActivity {
             return true;
         } else if (nextState.layer == state.layer + 1) {
             final Fragment fragment = Fragment.instantiate(this, nextState.fragment);
-            final FragmentTransaction transaction = getFragmentManager().beginTransaction()
+            final FragmentTransaction transaction = fragmentManager.beginTransaction()
                     .replace(R.id.master_fragment, fragment)
                     .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
             if (state.layer > 0)
                 transaction.addToBackStack(null);
             transaction.commit();
         } else if (nextState.layer == state.layer - 1) {
-            if (getFragmentManager().getBackStackEntryCount() == 0)
+            if (fragmentManager.getBackStackEntryCount() == 0)
                 return false;
-            getFragmentManager().popBackStack();
+            fragmentManager.popBackStack();
         } else if (nextState.layer < state.layer - 1) {
             moveToState(State.ofLayer(state.layer - 1));
             moveToState(nextState);
@@ -121,8 +123,8 @@ public class MainActivity extends BaseActivity {
     }
 
     private void updateActionBar() {
-        if (getActionBar() != null)
-            getActionBar().setDisplayHomeAsUpEnabled(state.layer > State.LIST.layer);
+        if (getSupportActionBar() != null)
+            getSupportActionBar().setDisplayHomeAsUpEnabled(state.layer > State.LIST.layer);
     }
 
     private enum State {

app/src/main/java/com/wireguard/android/activity/SettingsActivity.java

@@ -1,10 +1,11 @@
 package com.wireguard.android.activity;
 
-import android.app.Activity;
 import android.content.pm.PackageManager;
 import android.os.Bundle;
-import android.preference.Preference;
-import android.preference.PreferenceFragment;
+import android.support.annotation.NonNull;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceFragmentCompat;
 
 import com.wireguard.android.Application;
 import com.wireguard.android.R;
@@ -19,7 +20,7 @@ import java.util.List;
  * Interface for changing application-global persistent settings.
  */
 
-public class SettingsActivity extends Activity {
+public class SettingsActivity extends AppCompatActivity {
     @FunctionalInterface
     public interface PermissionRequestCallback {
         void done(String[] permissions, int[] grantResults);
@@ -56,7 +57,7 @@ public class SettingsActivity extends Activity {
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         final PermissionRequestCallback f = permissionRequestCallbacks.get(requestCode);
         if (f != null) {
             permissionRequestCallbacks.remove(requestCode);
@@ -67,17 +68,16 @@ public class SettingsActivity extends Activity {
     @Override
     protected void onCreate(final Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        if (getFragmentManager().findFragmentById(android.R.id.content) == null) {
-            getFragmentManager().beginTransaction()
+        if (getSupportFragmentManager().findFragmentById(android.R.id.content) == null) {
+            getSupportFragmentManager().beginTransaction()
                     .add(android.R.id.content, new SettingsFragment())
                     .commit();
         }
     }
 
-    public static class SettingsFragment extends PreferenceFragment {
+    public static class SettingsFragment extends PreferenceFragmentCompat {
         @Override
-        public void onCreate(final Bundle savedInstanceState) {
-            super.onCreate(savedInstanceState);
+        public void onCreatePreferences(final Bundle savedInstanceState, final String key) {
             addPreferencesFromResource(R.xml.preferences);
             if (Application.getComponent().getBackendType() != WgQuickBackend.class) {
                 final Preference toolsInstaller =

app/src/main/java/com/wireguard/android/activity/TunnelCreatorActivity.java

@@ -14,8 +14,8 @@ public class TunnelCreatorActivity extends BaseActivity {
     @SuppressWarnings("UnnecessaryFullyQualifiedName")
     protected void onCreate(final Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        if (getFragmentManager().findFragmentById(android.R.id.content) == null) {
-            getFragmentManager().beginTransaction()
+        if (getSupportFragmentManager().findFragmentById(android.R.id.content) == null) {
+            getSupportFragmentManager().beginTransaction()
                     .add(android.R.id.content, new TunnelEditorFragment())
                     .commit();
         }