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Question

我有 xml文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/Cell"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:background="@drawable/rect"
    android:orientation="vertical" >

<TextView
 android:id="@+id/tvText"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:gravity="center_vertical"
 android:minHeight="40dp"
 android:text="">
</TextView>
</LinearLayout>

它是带有空TextView的矩形50x50。

我尝试在我的自定义方法中获取此宽度：

@Override
protected void onCreate(Bundle savedInstanceState) {    
    ..............
    }

public void MyMethod(View v) {
     int CellWidth = ((LinearLayout) findViewById(R.id.Cell)).getWidth();
     //Toast.makeText(this, CellWidth, Toast.LENGTH_SHORT).show();
}

Eclipse中没有错误，但我的应用程序崩溃了。

但 如果我在屏幕上手动添加了Cell，那么在使用MyMethod之前，这个字符串可以正常工作。

int CellWidth = ((LinearLayout) findViewById(R.id.Cell)).getWidth();

但如果我添加吐司：

Toast.makeText(this, CellWidth, Toast.LENGTH_SHORT).show();

...然后app再次粉碎。

我做错了什么？

更新

感谢 Szymon 寻求解决Toast问题的帮助。

现在我有此代码：

protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Field = new GridView(this); Test = (LinearLayout) findViewById(R.id.Test); // Create the Custom Adapter Object FieldAdapter = new FieldAdapter(this); // Set the Adapter to GridView Field.setAdapter(FieldAdapter); } public void MyMethod(View v) { Field.setNumColumns(GridView.AUTO_FIT); Test.addView(Field); int CellWidth = ((LinearLayout) findViewById(R.id.Cell)).getWidth(); Toast.makeText(this, Integer.toString(CellWidth), Toast.LENGTH_SHORT).show();

如您所见，我添加我的GridView （其中包含Cell.xml作为每个单元格的布局）到屏幕：

Test.addView(Field);

之后，我试图获取Cell的getWidth（）。还是行不通。

但是，如果我会用其他方法延时 - 它会起作用。这是LogCat：

04-27 17:23:10.861: E/Trace(7482): error opening trace file: Permission denied (13) 04-27 17:23:10.861: D/ActivityThread(7482): setTargetHeapUtilization:0.25 04-27 17:23:10.861: D/ActivityThread(7482): setTargetHeapIdealFree:8388608 04-27 17:23:10.861: D/ActivityThread(7482): setTargetHeapConcurrentStart:2097152 04-27 17:23:10.971: D/libEGL(7482): loaded /system/lib/egl/libEGL_adreno200.so 04-27 17:23:10.971: D/libEGL(7482): loaded /system/lib/egl/libGLESv1_CM_adreno200.so 04-27 17:23:10.971: D/libEGL(7482): loaded /system/lib/egl/libGLESv2_adreno200.so 04-27 17:23:10.991: I/Adreno200-EGLSUB(7482): <ConfigWindowMatch:2087>: Format RGBA_8888. 04-27 17:23:11.001: E/(7482): <s3dReadConfigFile:75>: Can't open file for reading 04-27 17:23:11.011: E/(7482): <s3dReadConfigFile:75>: Can't open file for reading 04-27 17:23:11.051: D/OpenGLRenderer(7482): Enabling debug mode 0 04-27 17:23:11.161: W/IInputConnectionWrapper(7482): showStatusIcon on inactive InputConnection 04-27 17:23:11.161: W/IInputConnectionWrapper(7482): clearMetaKeyStates on inactive InputConnection 04-27 17:23:15.465: D/AndroidRuntime(7482): Shutting down VM 04-27 17:23:15.465: W/dalvikvm(7482): threadid=1: thread exiting with uncaught exception (group=0x40d66438) 04-27 17:23:15.475: E/AndroidRuntime(7482): FATAL EXCEPTION: main 04-27 17:23:15.475: E/AndroidRuntime(7482): java.lang.IllegalStateException: Could not execute method of the activity 04-27 17:23:15.475: E/AndroidRuntime(7482): at android.view.View$1.onClick(View.java:3598) 04-27 17:23:15.475: E/AndroidRuntime(7482): at android.view.View.performClick(View.java:4091) 04-27 17:23:15.475: E/AndroidRuntime(7482): at android.view.View$PerformClick.run(View.java:17036) 04-27 17:23:15.475: E/AndroidRuntime(7482): at android.os.Handler.handleCallback(Handler.java:615) 04-27 17:23:15.475: E/AndroidRuntime(7482): at android.os.Handler.dispatchMessage(Handler.java:92) 04-27 17:23:15.475: E/AndroidRuntime(7482): at android.os.Looper.loop(Looper.java:137) 04-27 17:23:15.475: E/AndroidRuntime(7482): at android.app.ActivityThread.main(ActivityThread.java:5070) 04-27 17:23:15.475: E/AndroidRuntime(7482): at java.lang.reflect.Method.invokeNative(Native Method) 04-27 17:23:15.475: E/AndroidRuntime(7482): at java.lang.reflect.Method.invoke(Method.java:511) 04-27 17:23:15.475: E/AndroidRuntime(7482): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795) 04-27 17:23:15.475: E/AndroidRuntime(7482): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558) 04-27 17:23:15.475: E/AndroidRuntime(7482): at dalvik.system.NativeStart.main(Native Method) 04-27 17:23:15.475: E/AndroidRuntime(7482): Caused by: java.lang.reflect.InvocationTargetException 04-27 17:23:15.475: E/AndroidRuntime(7482): at java.lang.reflect.Method.invokeNative(Native Method) 04-27 17:23:15.475: E/AndroidRuntime(7482): at java.lang.reflect.Method.invoke(Method.java:511) 04-27 17:23:15.475: E/AndroidRuntime(7482): at android.view.View$1.onClick(View.java:3593) 04-27 17:23:15.475: E/AndroidRuntime(7482): ... 11 more 04-27 17:23:15.475: E/AndroidRuntime(7482): Caused by: java.lang.NullPointerException 04-27 17:23:15.475: E/AndroidRuntime(7482): at com.example.field.MainActivity.CreateGrid(MainActivity.java:35) 04-27 17:23:15.475: E/AndroidRuntime(7482): ... 14 more 04-27 17:23:16.807: I/Process(7482): Sending signal. PID: 7482 SIG: 9

Answer 1

当你像这样使用toast时，你会调用makeText Toast类的CellWidth重载，因为第二个参数（int）属于makeText(Context context, int resId, int duration)类型：

makeText(Context context, CharSequence text, int duration)

作为id等于你的宽度的资源不存在，应用程序崩溃。

您希望使用此重载来显示字符串：

Toast.makeText(this, Integer.toString(CellWidth), Toast.LENGTH_SHORT).show();

你可以这样做：

{{1}}

Android - 应用在使用get.Width（）时崩溃

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1 个答案: