NavGraphNavigator.java
/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.navigation;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
/**
* A Navigator built specifically for {@link NavGraph} elements. Handles navigating to the
* correct destination when the NavGraph is the target of navigation actions.
*/
@Navigator.Name("navigation")
public class NavGraphNavigator extends Navigator<NavGraph> {
private final NavigatorProvider mNavigatorProvider;
/**
* Construct a Navigator capable of routing incoming navigation requests to the proper
* destination within a {@link NavGraph}.
*
* @param navigatorProvider NavigatorProvider used to retrieve the correct
* {@link Navigator} to navigate to the start destination
*/
public NavGraphNavigator(@NonNull NavigatorProvider navigatorProvider) {
mNavigatorProvider = navigatorProvider;
}
/**
* Creates a new {@link NavGraph} associated with this navigator.
* @return
*/
@NonNull
@Override
public NavGraph createDestination() {
return new NavGraph(this);
}
@Nullable
@Override
public NavDestination navigate(@NonNull NavGraph destination, @Nullable Bundle args,
@Nullable NavOptions navOptions, @Nullable Extras navigatorExtras) {
int startId = destination.getStartDestination();
if (startId == 0) {
throw new IllegalStateException("no start destination defined via"
+ " app:startDestination for "
+ destination.getDisplayName());
}
NavDestination startDestination = destination.findNode(startId, false);
if (startDestination == null) {
final String dest = destination.getStartDestDisplayName();
throw new IllegalArgumentException("navigation destination " + dest
+ " is not a direct child of this NavGraph");
}
Navigator<NavDestination> navigator = mNavigatorProvider.getNavigator(
startDestination.getNavigatorName());
return navigator.navigate(startDestination, startDestination.addInDefaultArgs(args),
navOptions, navigatorExtras);
}
@Override
public boolean popBackStack() {
return true;
}
}