小编Gud*_*guy的帖子

我有两个值，一个是 X 的基数，一个是 N 的幂，如何才能得到 X 的 N 次幂 ans。

任何代码将不胜感激。

我试图在启动后重新打开上次打开的屏幕，有什么简单的方法吗？欢迎提供示例代码！

到目前为止，我尝试了一个代码（我在某处找到了）SharedPreferences，但它不起作用。

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

String lastRouteKey = 'last_route';

void main() async {
  SharedPreferences preferences = await SharedPreferences.getInstance();
  String lastRoute = preferences.getString(lastRouteKey);
  runApp(MyApp(lastRoute));
}

class MyApp extends StatelessWidget {
  final String lastRoute;

  MyApp(this.lastRoute);

  @override
  Widget build(BuildContext context) {
    bool hasLastRoute = getWidgetByRouteName(lastRoute) != null;

    return MaterialApp(
      home: Foo(),
      initialRoute: hasLastRoute ? lastRoute : '/',
      onGenerateRoute: (RouteSettings route) {
        persistLastRoute(route.name);
        return MaterialPageRoute(
          builder: (context) => getWidgetByRouteName(route.name),
        );
      },
    );
  }

  Widget getWidgetByRouteName(String routeName) {
    switch (routeName) {
      case …

我遵循了Flutter官方网站上的所有步骤，并认为我已正确完成了所有操作，但是在构建时无法找到密钥库文件。

这是我显示的错误消息，而不是错误的路径 D:\flutterapps\testapp\key.jks：

PS D:\flutterapps\testapp> flutter build apk
Initializing gradle...                                       1.3s
Resolving dependencies...                                    4.3s
Gradle task 'assembleRelease'...

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:validateSigningRelease'.
> Keystore file 'D:\flutterapps\testapp\android\app\ D: lutterappspublishkey.jks' not found for signing config 'release'.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org …