在Java中将TextView的宽度更改为wrap_content

Question

我试图将TextView的宽度更改为wrap_content。

我迄今为止尝试是：

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

但是，当它运行的应用程序崩溃，我这是我在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

尝试，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)); 

或者只是从一开始就输入android.support.v7.widget.GridLayout.LayoutParams。 现在，导入为ViewGroup.LayoutParams，这不是GridLayout用于布局参数的。

编辑：既然你已经使用ViewGroup.LayoutParams使这些参数，像你这样的，可是它们分配给一个变量，而不是，姑且称之为viewGroupParams（所以保持ViewGroup.LayoutParams进口），那么这样做：

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

最后

txt.setLayoutParams (newParams);