相关疑难解决方法(0)

以前，我正在构建和运行 Flutter 应用程序。我不记得做了任何更改，但最近，我在通过 Android Studio 在智能手机上构建和运行应用程序时遇到了这样的错误：

Launching lib\main.dart on SM N900 in debug mode...
Running Gradle task 'assembleDebug'...
E/AndroidRuntime(12731): FATAL EXCEPTION: main
E/AndroidRuntime(12731): Process: io.flutter.demo.gallery, PID: 12731
E/AndroidRuntime(12731): java.lang.RuntimeException: Unable to start activity ComponentInfo{io.flutter.demo.gallery/io.flutter.demo.gallery.MainActivity}: android.content.res.Resources$NotFoundException: File res/drawable-v21/launch_background.xml from drawable resource ID #0x7f040000
E/AndroidRuntime(12731):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2693)
E/AndroidRuntime(12731):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2758)
E/AndroidRuntime(12731):    at android.app.ActivityThread.access$900(ActivityThread.java:177)
E/AndroidRuntime(12731):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1448)
E/AndroidRuntime(12731):    at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(12731):    at android.os.Looper.loop(Looper.java:145)
E/AndroidRuntime(12731):    at android.app.ActivityThread.main(ActivityThread.java:5942)
E/AndroidRuntime(12731):    at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(12731):    at java.lang.reflect.Method.invoke(Method.java:372)
E/AndroidRuntime(12731):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1400)
E/AndroidRuntime(12731):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1195)
E/AndroidRuntime(12731): Caused by: android.content.res.Resources$NotFoundException: …

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <stroke android:width="1px" android:color="#696969"/>
</shape>

此代码用于动态创建按钮，问题是我想设置背景颜色并设置背景可绘制对象。

Button btnTag = new Button(alltable.this);
btnTag.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, 
                       LinearLayout.LayoutParams.WRAP_CONTENT));
try {
    btnTag.setWidth(130);
    btnTag.setBackground(getResources().getDrawable(R.color.blue));

} catch (Exception e){
    e.printStackTrace();
}

这是一类，我想设置btn的背景色，然后使用我的drawable。