小编Liu*_*ong的帖子

我正在使用Flutter列出有关电影的信息.现在我想要左边的封面图片是圆角图片.我做了以下,但它没有奏效.谢谢!

    getItem(var subject) {
    var row = Container(
      margin: EdgeInsets.all(8.0),
      child: Row(
        children: <Widget>[
          Container(
            width: 100.0,
            height: 150.0,
            decoration: BoxDecoration(
              borderRadius: BorderRadius.all(Radius.circular(8.0)),
              color: Colors.redAccent,
            ),
            child: Image.network(
              subject['images']['large'],
              height: 150.0,
              width: 100.0,
            ),
          ),
        ],
      ),
    );
    return Card(
      color: Colors.blueGrey,
      child: row,
    );
  }

如下

我想使用Flutter web上传文件，但是遇到了一些问题，我的步骤如下：

/// choose file
  void _chooseFile() {
    InputElement uploadInput = FileUploadInputElement();
    uploadInput.accept = ".mp4";
    uploadInput.multiple = true;
    uploadInput.click();
    uploadInput.onChange.listen((event) {
      final files = uploadInput.files;
      if (files.length == 1) {
        final file = files[0];
        final reader = FileReader();
        reader.onLoadEnd.listen((event) {
          print('loaded: ${file.name}');
          print('type: ${reader.result.runtimeType}');
          print('file size = ${file.size}');
          _uploadFile(file);
        });
        reader.onError.listen((event) {
          print(event);
        });
        reader.readAsArrayBuffer(file);
      }
    });
  }

/// upload file
/// file: in dart:html package not in dart:io package
  void _uploadFile(File file) async {
    FormData data = FormData.fromMap({
      'file': …

Flutter 可以使用dart:ffi. 换句话说，Dart 可以调用 C++ 的方法，但是 C++ 可以调用 Dart 的方法吗？

如下？

我ConstraintLayout用作RecyclerView项目.但是现在有一些问题显示在真机上并且在预览中不一样

recyclerView项目布局如下:

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/foreground_item_undo"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white"
    android:orientation="horizontal"
    app:layout_constraintWidth_default="spread">

    <com.lsl.wordhelper.view.RoundBgTextView
        android:id="@+id/tv_item_icon"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_marginStart="8dp"
        android:gravity="center"
        android:padding="4dp"
        android:text="G"
        android:textColor="@android:color/white"
        android:textSize="30sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/tv_item_explain"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="???"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="@id/tv_item_original"
        app:layout_constraintTop_toTopOf="parent" />


    <TextView
        android:id="@+id/tv_item_original"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:text="Good"
        android:textColor="@android:color/black"
        android:textSize="24sp"
        app:layout_constraintBottom_toTopOf="@id/tv_item_explain"
        app:layout_constraintLeft_toRightOf="@id/tv_item_icon"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/tv_item_translate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="??"
        android:textColor="@android:color/black"
        android:textSize="16sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="@id/tv_item_original"
        app:layout_constraintTop_toBottomOf="@id/tv_item_explain" />

    <TextView
        android:id="@+id/tv_item_date"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="16dp"
        android:gravity="right"
        android:text="2018/01/19"
        android:textColor="@color/text_color_date"
        app:layout_constraintBottom_toBottomOf="@id/tv_item_original"
        app:layout_constraintRight_toRightOf="parent" />
</android.support.constraint.ConstraintLayout>

在Android Studio预览中.

但是在电话里

有什么问题？

大家好？我有一个问题，我不明白之间的差别AnimatedWidget和AnimatedBuilder。源码中的注释如下：

动画小部件：

/// For more complex case involving additional state, consider using
/// [AnimatedBuilder].

动画生成器：

/// For simple cases without additional state, consider using
/// [AnimatedWidget].

我想知道如何在它们之间进行选择，因为我不太了解文档，谢谢！

用dart编写构造函数时遇到问题。我有一个带有两个最终变量的类，在构造函数中对其进行初始化，以下是错误的，因为最终变量没有setter方法？

class Person{
  final String name;
  final int age; 

  // Error
  Person(String name, int age) {
    this.name = name;
    this.age = age;
  }
}

但这是正确的，为什么

class Person{
  final String name;
  final int age; 

  // Correct
  Person(String name, int age): this.name = name, this.age = age;
}

我使用Android Studio和Unity开发,将Library打包成aar文件,然后将aar文件作为Unity插件.当我使用Java时没问题,但是当使用Kotlin时,它会引发异常.谢谢!

例外:

 AndroidJavaException: java.lang.NoClassDefFoundError: Failed resolution of: Lkotlin/jvm/internal/Intrinsics;
                                    java.lang.NoClassDefFoundError: Failed resolution of: Lkotlin/jvm/internal/Intrinsics;
                                        at com.lsl.plugin.PluginActivity.showToast(PluginActivity.kt)
                                        at com.unity3d.player.UnityPlayer.nativeRender(Native Method)
                                        at com.unity3d.player.UnityPlayer.c(Unknown Source)
                                        at com.unity3d.player.UnityPlayer$c$1.handleMessage(Unknown Source)
                                        at android.os.Handler.dispatchMessage(Handler.java)
                                        at android.os.Looper.loop(Looper.java)
                                        at com.unity3d.player.UnityPlayer$c.run(Unknown Source)
                                     Caused by: java.lang.ClassNotFoundException: Didn't find class "kotlin.jvm.internal.Intrinsics" on path: DexPathList[[zip file "/data/app/com.lsl.aardemo-1/base.apk"],nativeLibraryDirectories=[/data/app/com.lsl.aardemo-1/lib/arm, /data/app/com.lsl.aardemo-1/base.apk!/lib/armeabi-v7a, /vendor/lib, /system/lib]]
                                        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
                                        at java.lang.ClassLoader.loadClass(ClassL

活动

class PluginActivity : UnityPlayerActivity() {
fun showToast(msg: String) {
    runOnUiThread {
        Toast.makeText(this@PluginActivity.applicationContext, msg, Toast.LENGTH_SHORT).show()
    }
}

}

.cs脚本

    public static AndroidTools GetInstance(){
    if (instance == null) {
        lock …