Flutter 中的 pushReplacementNamed 和 popAndPushNamed 有什么区别? [英] What is the difference between pushReplacementNamed and popAndPushNamed in Flutter?

问题描述

Flutter#navigator.dart 中的 NavigatorState 类有 2 个具有类似行为的方法.Flutter中的pushReplacementNamed和popAndPushNamed有什么区别?

pushReplacementNamed

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通过推送名为 [routeName] 的路线替换导航器的当前路线，然后在新路线完成动画处理后处理先前的路线.

popAndPushNamed

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从导航器中弹出当前路线并在其位置推送命名路线.

解决方案

如果你有数据结构方面的知识，那么你就知道堆栈.如果你对stacks有基本的了解，那么你就知道push和pop了.

如果你不这样做，推入是将元素添加到元素堆栈的顶部，而弹出是从同一堆栈中移除顶部元素.

所以在 Flutter 的情况下，当我们导航到另一个屏幕时，我们使用 push 方法和 Navigatorwidget 将新屏幕添加到堆栈的顶部.自然地，pop 方法会从堆栈中删除该屏幕.

让我们转到

现在，当我们想要摆脱最后访问的屏幕时，在这种情况下是 Screen2，我们需要使用 pop 从导航器的堆栈中 popRoutes方法.

Navigator.of(context).pop();

请记住，这行代码位于您的 onPressed 方法中.

当使用 Scaffold 时，通常不需要显式弹出路由，因为 Scaffold 会自动在其 AppBar 中添加一个返回"按钮，该按钮会在按下时调用 Navigator.pop().即使在 Android 中，按下设备后退按钮也会执行相同的操作.但是，您可能需要将此方法用于其他用例，例如当用户单击取消"按钮时弹出 AlertDialog.

用例:pushReplacementNamed

当用户成功登录并且现在可能在 DashboardScreen 上时，无论如何您都不希望用户返回 LoginScreen.所以登录路由应该完全被仪表板路由代替.另一个例子是从 SplashScreen 转到 HomeScreen.它应该只显示一次，并且用户不能再次从 HomeScreen 回到它.在这种情况下，由于我们要进入一个全新的屏幕，我们可能希望将这个方法用于它的 enter 动画属性.

用例:popAndPushNamed

假设，您正在构建一个购物应用程序，该应用程序在其 ProductsListScreen 中显示产品列表，并且用户可以在 FiltersScreen 中应用过滤器.当用户单击 Apply Changes 按钮时，FiltersScreen 应该会弹出并使用新的过滤器值推送回 ProductsListScreen.这里 popAndPushNamed 的退出动画属性看起来更合适.

pushReplacementNamed 将执行进入动画，popAndPushNamed 将执行退出动画.Navigator.of(context).pushReplacementNamed('/screen4');//和Navigator.popAndPushNamed(context, '/screen4');

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The NavigatorState class in Flutter#navigator.dart have 2 method with the similar behavior. What is the difference between pushReplacementNamed and popAndPushNamed in Flutter?

pushReplacementNamed

Replace the current route of the navigator by pushing the route named [routeName] and then disposing the previous route once the new route has finished animating in.

popAndPushNamed

Pop the current route off the navigator and push a named route in its place.

解决方案

If you have any knowledge in Data Structures, then you know about Stacks. If you have even basic knowledge of stacks, then you know about pushand pop.

If you don’t, pushing is adding element to the top of a stack of elements and popping is removing the top element from the same stack.

So in case of Flutter, when we navigate to another screen, we use the pushmethods and Navigatorwidget adds the new screen onto the top of the stack. Naturally, the popmethods would remove that screen from the stack.

So lets move to the codebase of our Sample_Project and let’s see how we can move from Screen1 to Screen2. You can experiment with the methods by running the sample app.

new RaisedButton(
   onPressed:(){
   Navigator.of(context).pushNamed('/screen2');
},
   child: new Text("Push to Screen 2"),
),

That was short.

That was indeed. With the help of pushNamedmethods, we can navigate to any screen whose route is defined in main.dart. We call them namedRoutefor reference. The use-case of this method is pretty straightforward. To simply navigate.

Pop it

Now when we want to get rid of the last visited screen, which is Screen2in this case, we would need to popRoutes from the Navigator’s stack using the pop methods.

Navigator.of(context).pop();

Remember, this line of code goes inside your onPressedmethod.

When using Scaffold, it usually isn’t necessary to explicitly pop the route, because the Scaffold automatically adds a ‘back’ button to its AppBar, which would call Navigator.pop() on pressed. Even in Android, pressing the device back button would do the same. But nevertheless, you might need this method for other usecases such as popping an AlertDialog when user clicks on Cancel button.

Use-case : pushReplacementNamed

When the user has logged in successfully, and are now on the DashboardScreenperhaps, then you don’t want the user to go back to LoginScreen in any case. So login route should be completely replaced by the dashboard route. Another example would be going to HomeScreen from SplashScreen. It should only display once and the user should not be able to go back to it from HomeScreen again. In such cases, since we are going to a completely new screen, we may want to use this method for its enter animation property.

Use-case: popAndPushNamed

Suppose, you are building a Shopping app that displays a list of the products in its ProductsListScreen and user can apply filters in the FiltersScreen. When the user clicks on the Apply Changes button, the FiltersScreenshould pop and push back to the ProductsListScreen with the new filter values. Here the exit animation property of popAndPushNamed would look more appropriate.

pushReplacementNamed will execute the enter animation and popAndPushNamed will execute the exit animation.

Navigator.of(context).pushReplacementNamed('/screen4');
                       //and
Navigator.popAndPushNamed(context, '/screen4');

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