在Java中將TextView的寬度更改爲wrap_content

Question

我試圖將TextView的寬度更改爲wrap_content。

我迄今爲止嘗試是：

TextView txt = (TextView) findViewById(R.id.txtViewContents); 
txt.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); 

但是，當它運行的應用程序崩潰，我這是我在logcat中得到：

E/AndroidRuntime(2213): FATAL EXCEPTION: main 
E/AndroidRuntime(2213): java.lang.ClassCastException: android.view.ViewGroup$LayoutParams cannot be cast to android.support.v7.widget.GridLayout$LayoutParams 
E/AndroidRuntime(2213):  at android.support.v7.widget.GridLayout.computeLayoutParamsHashCode(GridLayout.java:872) 
E/AndroidRuntime(2213):  at android.support.v7.widget.GridLayout.checkForLayoutParamsModification(GridLayout.java:879) 
E/AndroidRuntime(2213):  at android.support.v7.widget.GridLayout.onMeasure(GridLayout.java:927) 
E/AndroidRuntime(2213):  at android.view.View.measure(View.java:15513) 
E/AndroidRuntime(2213):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4827) 
E/AndroidRuntime(2213):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
E/AndroidRuntime(2213):  at android.view.View.measure(View.java:15513) 
E/AndroidRuntime(2213):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:847) 
E/AndroidRuntime(2213):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 
E/AndroidRuntime(2213):  at android.view.View.measure(View.java:15513) 
E/AndroidRuntime(2213):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4827) 
E/AndroidRuntime(2213):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
E/AndroidRuntime(2213):  at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176) 
E/AndroidRuntime(2213):  at android.view.View.measure(View.java:15513) 
E/AndroidRuntime(2213):  at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874) 
E/AndroidRuntime(2213):  at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089) 
E/AndroidRuntime(2213):  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265) 
E/AndroidRuntime(2213):  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989) 
E/AndroidRuntime(2213):  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351) 
E/AndroidRuntime(2213):  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 
E/AndroidRuntime(2213):  at android.view.Choreographer.doCallbacks(Choreographer.java:562) 
E/AndroidRuntime(2213):  at android.view.Choreographer.doFrame(Choreographer.java:532) 
E/AndroidRuntime(2213):  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 
E/AndroidRuntime(2213):  at android.os.Handler.handleCallback(Handler.java:725) 
E/AndroidRuntime(2213):  at android.os.Handler.dispatchMessage(Handler.java:92) 
E/AndroidRuntime(2213):  at android.os.Looper.loop(Looper.java:137) 
E/AndroidRuntime(2213):  at android.app.ActivityThread.main(ActivityThread.java:5039) 
E/AndroidRuntime(2213):  at java.lang.reflect.Method.invokeNative(Native Method) 
E/AndroidRuntime(2213):  at java.lang.reflect.Method.invoke(Method.java:511) 
E/AndroidRuntime(2213):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
E/AndroidRuntime(2213):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
E/AndroidRuntime(2213):  at dalvik.system.NativeStart.main(Native Method) 

Answer 1

嘗試，而不是

setLayoutParams(new android.support.v7.widget.GridLayout.LayoutParams(android.support.v7.widget.GridLayout.LayoutParams.WRAP_CONTENT, android.support.v7.widget.GridLayout.LayoutParams.WRAP_CONTENT)); 

或者只是從一開始就輸入android.support.v7.widget.GridLayout.LayoutParams。 現在，導入爲ViewGroup.LayoutParams，這不是GridLayout用於佈局參數的。

編輯：既然你已經使用ViewGroup.LayoutParams使這些參數，像你這樣的，可是它們分配給一個變量，而不是，姑且稱之爲viewGroupParams（所以保持ViewGroup.LayoutParams進口），那麼這樣做：

android.support.v7.widget.GridLayout.LayoutParams newParams = new android.support.v7.widget.GridLayout.LayoutParams (viewGroupParams); 

最後

txt.setLayoutParams (newParams);