java - 微调器，如果再次选择项目

Question

我在包中创建了一个名为 NoDefaultSpinner 的类文件。但是，当我尝试在我的 Android 应用程序中使用它时，我遇到了导致程序崩溃的异常。

我从 this link 复制了 Dimitar Vukman 和 Blundell 提供的代码然后在 Alex Miragall 指示一些帖子时更新此代码(因为现在我正在为 Android 4.0 创建应用程序)。我删除了 Dimitar 的 onClick 方法并在类(class)末尾粘贴了 Alex 的代码。

然后我用旋转器编辑我的 Activity ，我改变了

static Spinner spinner1;

到

static NoDefaultSpinner spinner1;

和

variables.spinner1 = (Spinner) findViewById(R.id.spinner1); 

到

variables.spinner1 = (NoDefaultSpinner) findViewById(R.id.spinner1); 

我也试着改变

<Spinner
        android:id="@+id/spinner1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/place" />

到

<NoDefaultSpinner
        android:id="@+id/spinner1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/place" />

问题:我做错了什么，为什么我的应用程序崩溃了，我该怎么做才能让它正常工作？

如果我不更新布局，这些是错误:

01-08 01:50:48.835: E/AndroidRuntime(13362): FATAL EXCEPTION: main
01-08 01:50:48.835: E/AndroidRuntime(13362): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.life/com.example.life.search_activity}: java.lang.ClassCastException: android.widget.Spinner cannot be cast to com.example.life.NoDefaultSpinner
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.app.ActivityThread.access$600(ActivityThread.java:141)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.os.Handler.dispatchMessage(Handler.java:99)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.os.Looper.loop(Looper.java:137)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.app.ActivityThread.main(ActivityThread.java:5039)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at java.lang.reflect.Method.invokeNative(Native Method)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at java.lang.reflect.Method.invoke(Method.java:511)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at dalvik.system.NativeStart.main(Native Method)
01-08 01:50:48.835: E/AndroidRuntime(13362): Caused by: java.lang.ClassCastException: android.widget.Spinner cannot be cast to com.example.life.NoDefaultSpinner
01-08 01:50:48.835: E/AndroidRuntime(13362):    at com.example.life.search_activity.onCreate(search_activity.java:181)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.app.Activity.performCreate(Activity.java:5104)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
01-08 01:50:48.835: E/AndroidRuntime(13362):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
01-08 01:50:48.835: E/AndroidRuntime(13362):    ... 11 more

如果我更新布局(将 Spinner 更改为 NoDefaultSpinner)，这些都是错误

01-08 01:53:22.803: E/AndroidRuntime(13417): FATAL EXCEPTION: main
01-08 01:53:22.803: E/AndroidRuntime(13417): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.life/com.example.life.search_activity}: android.view.InflateException: Binary XML file line #7: Error inflating class NoDefaultSpinner
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.app.ActivityThread.access$600(ActivityThread.java:141)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.os.Handler.dispatchMessage(Handler.java:99)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.os.Looper.loop(Looper.java:137)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.app.ActivityThread.main(ActivityThread.java:5039)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at java.lang.reflect.Method.invokeNative(Native Method)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at java.lang.reflect.Method.invoke(Method.java:511)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at dalvik.system.NativeStart.main(Native Method)
01-08 01:53:22.803: E/AndroidRuntime(13417): Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class NoDefaultSpinner
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:698)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:270)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.app.Activity.setContentView(Activity.java:1881)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at com.example.life.search_activity.onCreate(search_activity.java:177)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.app.Activity.performCreate(Activity.java:5104)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
01-08 01:53:22.803: E/AndroidRuntime(13417):    ... 11 more
01-08 01:53:22.803: E/AndroidRuntime(13417): Caused by: java.lang.ClassNotFoundException: Didn't find class "android.view.NoDefaultSpinner" on path: /data/app/com.example.life-1.apk
01-08 01:53:22.803: E/AndroidRuntime(13417):    at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:65)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.view.LayoutInflater.createView(LayoutInflater.java:552)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.view.LayoutInflater.onCreateView(LayoutInflater.java:643)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:66)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.view.LayoutInflater.onCreateView(LayoutInflater.java:660)
01-08 01:53:22.803: E/AndroidRuntime(13417):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:685)
01-08 01:53:22.803: E/AndroidRuntime(13417):    ... 21 more

我在堆栈上找到了两个解决我的问题的方法:

The first

The second

我和问这些问题的人有同样的问题。那里很好地提出了问题。

我尝试了所有解决方案，但每次我尝试使用这些特殊微调器启动 Activity 时，应用程序都会崩溃。也许我确实用错了类？

Answer 1

你的第一个异常是由

引起的

java.lang.ClassNotFoundException: Didn't find class "android.view.NoDefaultSpinner" on path: /data/app/com.example.life-1.apk

因此在您的 xml 布局中使用完全限定名称 (com.myPackage.NoDefaultSpinner)。否则，Android 会假定该类是它自己的包的一部分，并且它显然会失败。

另外，这个:

ClassCastException: android.widget.Spinner cannot be cast to com.example.life.NoDefaultSpinner

建议 NoDefaultSpinner 不扩展 Spinner，确保它是。