在Android中将类扩展为xml文件

时间：2015-02-06 18:21:13

标签： java android android-layout

最近我在一个Android项目中工作，我需要将我的类膨胀到我的.xml文件中，我的班级是

public class FacebookWebView extends WebView {

    public FacebookWebView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
    }

}

我的XML代码是

<android.support.v4.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/layout_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".FacebookNewWrapper" >

    <RelativeLayout
        android:id="@+id/webview_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <com.example.tainfal.FacebookWebView
            android:id="@+id/webview"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fadeScrollbars="true"
            android:focusable="true"
            android:focusableInTouchMode="true" />

        <ProgressBar
            android:id="@+id/progress_bar"
            style="@style/Widget.Tinfoil.ProgressBar"
            android:layout_width="match_parent"
            android:layout_height="@dimen/webview_top_progress_bar"
            android:layout_alignParentTop="true"
            android:layout_marginTop="@dimen/webview_top_progress_bar_top_margin" />
    </RelativeLayout>

    <FrameLayout
        android:id="@+id/fullscreen_custome_content"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/black"
        android:visibility="gone" >
    </FrameLayout>

    <include layout="@layout/drawer_menu" />
</android.support.v4.widget.DrawerLayout>

Log cat错误是.... 

  02-06 23:58:42.773: E/Trace(22653): error opening trace file: No such    file or directory (2)
  02-06 23:58:43.013: E/AndroidRuntime(22653): FATAL EXCEPTION: main
  02-06 23:58:43.013: E/AndroidRuntime(22653)java.lang.RuntimeException: Unable to start activity 
 ComponentInfo{com.example.tainfal/com.example.tainfal.MainActivity}:   android.view.InflateException: Binary XML file line #19: Error inflating class com.example.tainfal.FacebookWebView
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2355)
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2391)
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at android.app.ActivityThread.access$600(ActivityThread.java:151)
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1335)
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at android.os.Handler.dispatchMessage(Handler.java:99)
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at android.os.Looper.loop(Looper.java:155)
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at android.app.ActivityThread.main(ActivityThread.java:5511)
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at java.lang.reflect.Method.invokeNative(Native Method)
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at java.lang.reflect.Method.invoke(Method.java:511)
  02-06 23:58:43.013: E/AndroidRuntime(22653):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1029)

当我运行我的项目时，它停止了。 我是Android开发新手我没有关于在XML文件中膨胀类的经验，我怎么能解决这个问题。

2 个答案:

答案 0 :(得分：2)

根据Android Developer Documentation：

  

要允许Android开发人员工具与您的视图进行互动，请访问   至少你必须提供一个构造函数，它接受一个Context和一个   AttributeSet对象作为参数。此构造函数允许布局编辑器创建和编辑视图的实例。

所以你需要一个带有FacebookWebView的两个参数的构造函数：

 public FacebookWebView(Context context, AttributeSet attrs) {
     super(context,attrs);        
 }

否则LogCat将报告以下异常：

 02-07 00:45:49.879  23086-23086/android.stackoverflow.com.sofapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: android.stackoverflow.com.sofapplication, PID: 23086
java.lang.RuntimeException: Unable to start activity ComponentInfo{android.stackoverflow.com.sofapplication/android.stackoverflow.com.sofapplication.MainActivity}: android.view.InflateException: Binary XML file line #41: Error inflating class com.sof.q28372281.FacebookWebView
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2314)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388)
        at android.app.ActivityThread.access$800(ActivityThread.java:148)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5312)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
 Caused by: android.view.InflateException: Binary XML file line #41: Error inflating class com.sof.q28372281.FacebookWebView
        at android.view.LayoutInflater.createView(LayoutInflater.java:616)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
        at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:228)
        at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
        at android.stackoverflow.com.sofapplication.MainActivity.onCreate(MainActivity.java:21)
        at android.app.Activity.performCreate(Activity.java:5953)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1128)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2267)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388)
            at android.app.ActivityThread.access$800(ActivityThread.java:148)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5312)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
 Caused by: java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]
        at java.lang.Class.getConstructor(Class.java:531)
        at java.lang.Class.getConstructor(Class.java:495)
        at android.view.LayoutInflater.createView(LayoutInflater.java:580)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
            at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:228)
            at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
            at android.stackoverflow.com.sofapplication.MainActivity.onCreate(MainActivity.java:21)
            at android.app.Activity.performCreate(Activity.java:5953)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1128)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2267)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388)
            at android.app.ActivityThread.access$800(ActivityThread.java:148)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5312)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)

答案 1 :(得分：0)

过了一段时间我已经解决了。我必须将它添加到构造函数

 public FacebookWebView(Context context) {
    super(context);
    // TODO Auto-generated constructor stub
}

public FacebookWebView(Context context, AttributeSet attrs) {
    super(context, attrs);
    // TODO Auto-generated constructor stub
}
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