Question

此.NET C＃应用程序存在以下问题。

我有这个字符串数组：

string[] uorsList = uors.Split(';');

有时此数组包含与空字符串（“”）对应的元素。

从此 uorsList 数组中删除所有为空字符串的元素的聪明方法是什么？

Answer 1

您可以使用LINQ来过滤出空的整体：

using System.Linq;
...

string[] uorsList = uors.Split(';');
var filtered = uorsList.Where(s=> !string.IsNullOrWhiteSpace(s)).ToArray();

编辑：

正如注释中指出的那样，使用string.Split时，以下选项是更好的选择，因为空条目永远不会进入数组：


string[] uorsList = uors.Split(new[] { ";" }, StringSplitOptions.RemoveEmptyEntries);

Answer 2

您可以尝试以下操作：

import 'package:flutter/material.dart';

  void main() => runApp(MyApp());

  class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        title: 'Flutter Demo',
        home: MyHomePage(),
      );
    }
  }

  class MyHomePage extends StatefulWidget {
    @override
    _MyHomePageState createState() => _MyHomePageState();
  }

  class _MyHomePageState extends State<MyHomePage> {
    List<String> data = ['Page 0', 'Page 1', 'Page 2'];
    int initPosition = 1;

    @override
    Widget build(BuildContext context) {
      return Scaffold(
        body: SafeArea(
          child: CustomTabView(
            initPosition: initPosition,
            itemCount: data.length,
            tabBuilder: (context, index) => Tab(text: data[index]),
            pageBuilder: (context, index) => Center(child: Text(data[index])),
            onPositionChange: (index){
              print('current position: $index');
              initPosition = index;
            },
            onScroll: (position) => print('$position'),
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            setState(() {
              data.add('Page ${data.length}');
            });
          },
          child: Icon(Icons.add),
        ),
      );
    }
  }

  /// Implementation

  class CustomTabView extends StatefulWidget {
    final int itemCount;
    final IndexedWidgetBuilder tabBuilder;
    final IndexedWidgetBuilder pageBuilder;
    final Widget stub;
    final ValueChanged<int> onPositionChange;
    final ValueChanged<double> onScroll;
    final int initPosition;

    CustomTabView({
      @required this.itemCount,
      @required this.tabBuilder,
      @required this.pageBuilder,
      this.stub,
      this.onPositionChange,
      this.onScroll,
      this.initPosition,
    });

    @override
    _CustomTabsState createState() => _CustomTabsState();
  }

  class _CustomTabsState extends State<CustomTabView> with TickerProviderStateMixin {
    TabController controller;
    int _currentCount;
    int _currentPosition;

    @override
    void initState() {
      _currentPosition = widget.initPosition ?? 0;
      controller = TabController(
        length: widget.itemCount,
        vsync: this,
        initialIndex: _currentPosition,
      );
      controller.addListener(onPositionChange);
      controller.animation.addListener(onScroll);
      _currentCount = widget.itemCount;
      super.initState();
    }

    @override
    void didUpdateWidget(CustomTabView oldWidget) {
      if (_currentCount != widget.itemCount) {
        controller.animation.removeListener(onScroll);
        controller.removeListener(onPositionChange);
        controller.dispose();

        if (widget.initPosition != null) {
          _currentPosition = widget.initPosition;
        }

        if (_currentPosition > widget.itemCount - 1) {
            _currentPosition = widget.itemCount - 1;
            _currentPosition = _currentPosition < 0 ? 0 : 
            _currentPosition;
            if (widget.onPositionChange is ValueChanged<int>) {
               WidgetsBinding.instance.addPostFrameCallback((_){
                if(mounted) {
                  widget.onPositionChange(_currentPosition);
                }
               });
            }
         }

        _currentCount = widget.itemCount;
        setState(() {
          controller = TabController(
            length: widget.itemCount,
            vsync: this,
            initialIndex: _currentPosition,
          );
          controller.addListener(onPositionChange);
          controller.animation.addListener(onScroll);
        });
      } else if (widget.initPosition != null) {
        controller.animateTo(widget.initPosition);
      }

      super.didUpdateWidget(oldWidget);
    }

    @override
    void dispose() {
      controller.animation.removeListener(onScroll);
      controller.removeListener(onPositionChange);
      controller.dispose();
      super.dispose();
    }

    @override
    Widget build(BuildContext context) {
      if (widget.itemCount < 1) return widget.stub ?? Container();

      return Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: <Widget>[
          Container(
            alignment: Alignment.center,
            child: TabBar(
              isScrollable: true,
              controller: controller,
              labelColor: Theme.of(context).primaryColor,
              unselectedLabelColor: Theme.of(context).hintColor,
              indicator: BoxDecoration(
                border: Border(
                  bottom: BorderSide(
                    color: Theme.of(context).primaryColor,
                    width: 2,
                  ),
                ),
              ),
              tabs: List.generate(
                widget.itemCount,
                    (index) => widget.tabBuilder(context, index),
              ),
            ),
          ),
          Expanded(
            child: TabBarView(
              controller: controller,
              children: List.generate(
                widget.itemCount,
                    (index) => widget.pageBuilder(context, index),
              ),
            ),
          ),
        ],
      );
    }

    onPositionChange() {
      if (!controller.indexIsChanging) {
        _currentPosition = controller.index;
        if (widget.onPositionChange is ValueChanged<int>) {
          widget.onPositionChange(_currentPosition);
        }
      }
    }

    onScroll() {
      if (widget.onScroll is ValueChanged<double>) {
        widget.onScroll(controller.animation.value);
      }
    }
  }

Answer 3

以下是一些方法：

    @PostMapping("/testCal")
    public void testCal(@RequestBody TestCal test) {

    // do your stuff
    test.getCalendar();


   }

如何从C＃中的字符串数组中删除空字符串？

3 个答案: