我正在编写一段代码，根据应用程序提供的屏幕尺寸来更改其大小。它通过View的onSizeChanged()和onDraw()方法获取整个宽度和高度（或其适当视图的w和h）。
在另一个代码中，它运行良好，但现在每次我尝试输入“setLayoutParams()”命令时，它都会显示错误消息。您能帮助我解决这个问题吗？实际上，在代码中任何地方都无法使用setLayoutParams()。以下是主类代码。
public class ManipulateDesign extends Activity {
private LinearLayout ll;
private ScrollView sv;
private TextView tv;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ll = (LinearLayout) findViewById(R.id.ll);
sv = (ScrollView) findViewById(R.id.sv);
tv = new TextView(this);
tv.setText("You're in the first ScrollView\n" +
"- Living Universe \n" +
"Wish (upon a star) Hope to (be again)\n" +
"The one you find, when all is done and through!\n" +
"If all, made a wish to save, the star would it be in vain?\n" +
"So much it holds, too dear to part, many ways to see the light of answers!\n" +
"For all was once, just taken away, that one hope all disappeared so none can break nor brittle my heart\n" +
"no, never again, until the end");
sv.addView(tv);
ChangeSizeView csv = new ChangeSizeView(getApplicationContext());
ll.addView(csv);
}
class ChangeSizeView extends View{
int newWidth;
int newHeight;
public ChangeSizeView(Context context) {
super(context);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
newWidth = w;
newHeight = h;
super.onSizeChanged(w, h, oldw, oldh);
}
@Override
protected void onDraw(Canvas canvas) {
// THIS COMMAND MAKES AN ERROR(not just in this method but anywhere in the entire code) BUT WORKED WELL IN ANOTHER CODE
sv.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, (newHeight - 100)));
super.onDraw(canvas);
}
}
}
这是我的 main.xml 文件。
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/ll"
>
<ScrollView android:id="@+id/sv"
android:layout_height="wrap_content"
android:layout_width="wrap_content">
</ScrollView>
</LinearLayout>
这是显示错误信息的logcat标识
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): FATAL EXCEPTION: main
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): java.lang.ClassCastException: android.view.ViewGroup$LayoutParams
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.widget.LinearLayout.measureVertical(LinearLayout.java:355)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.widget.LinearLayout.onMeasure(LinearLayout.java:304)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.view.View.measure(View.java:8171)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.view.View.measure(View.java:8171)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.widget.LinearLayout.measureVertical(LinearLayout.java:526)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.widget.LinearLayout.onMeasure(LinearLayout.java:304)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.view.View.measure(View.java:8171)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.view.View.measure(View.java:8171)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.view.ViewRoot.performTraversals(ViewRoot.java:801)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.view.ViewRoot.handleMessage(ViewRoot.java:1727)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.os.Handler.dispatchMessage(Handler.java:99)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.os.Looper.loop(Looper.java:123)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at android.app.ActivityThread.main(ActivityThread.java:4627)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at java.lang.reflect.Method.invokeNative(Native Method)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at java.lang.reflect.Method.invoke(Method.java:521)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-11 06:39:52.148: ERROR/AndroidRuntime(2952): at dalvik.system.NativeStart.main(Native Method)