关于一个奇怪的ClassCastException

　

classcastexception

关于一个奇怪的classcastexception：Android.widget.relativelayout$layoutparams cannot be cast to android.support.v4.widget.drawerLayout$LayoutParams

今天在写自定义相机的时候发现一个莫名其妙的异常情况：android.widget.RelativeLayout$LayoutParams cannot be cast to android.support.v4.widget.DrawerLayout$LayoutParams

具体Logcat打印的异常信息如下：可以看出没有报出具体的位置。

05-08 17:35:39.817 26736-26736/? E/Androidruntime: FATAL EXCEPTION: main
                                                   Process: com.example.lenovo.raispaceandroid, PID: 26736
                                                   java.lang.ClassCastException: android.widget.RelativeLayout$LayoutParams cannot be cast to android.support.v4.widget.DrawerLayout$LayoutParams
                                                       at android.support.v4.widget.DrawerLayout.onmeasure(DrawerLayout.java:1016)
                                                       at android.view.View.measure(View.java:19886)
                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6085)
                                                       at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                       at android.support.v7.widget.contentFrameLayout.onMeasure(ContentFrameLayout.java:139)
                                                       at android.view.View.measure(View.java:19886)
                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6085)
                                                       at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
                                                       at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
                                                       at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
                                                       at android.view.View.measure(View.java:19886)
                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6085)
                                                       at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                       at android.view.View.measure(View.java:19886)
                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6085)
                                                       at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
                                                       at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
                                                       at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
                                                       at android.view.View.measure(View.java:19886)
                                                       at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6085)
                                                       at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                       at com.android.internal.policy.DecorView.onMeasure(DecorView.java:692)
                                                       at android.view.View.measure(View.java:19886)
                                                       at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2328)
                                                       at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1419)
                                                       at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1672)
                                                       at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1307)
                                                       at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6422)
                                                       at android.view.Choreographer$CallbackRecord.run(Choreographer.java:876)
                                                       at android.view.Choreographer.doCallbacks(Choreographer.java:688)
                                                       at android.view.Choreographer.doFrame(Choreographer.java:623)
                                                       at android.view.Choreographer$FramedisplayEventReceiver.run(Choreographer.java:862)
                                                       at android.os.handler.handleCallback(Handler.java:754)
                                                       at android.os.Handler.dispatchmessage(Handler.java:95)
                                                       at android.os.Looper.loop(Looper.java:163)
                                                       at android.APP.activitythread.main(ActivityThread.java:6389)
                                                       at java.lang.reflect.method.invoke(Native Method)
                                                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
                                                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:791)

搜了很多文章之后，仔细分析之后发现是因为我添加的自定义相机类Camerasurfaceview中有这么一段：

// 根据选出的PictureSize重新设置SurfaceView大小
            float w = picSize.width;
            float h = picSize.height;
            parameters.setPictureSize(picSize.width, picSize.height);   //设置照片分辨率大小
            this.setLayoutParams(new RelativeLayout.LayoutParams((int) (height * (h / w)), height));

错误正式因为正是这一句：

this.setLayoutParams(new RelativeLayout.LayoutParams((int) (height * (h / w)), height))。

因为我的Activity的根布局是DrawerLayout。

所以改为：

this.setLayoutParams(new DrawerLayout.LayoutParams((int) (height * (h / w)), height))

即可。

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