如何清除布局上的内容？

本文介绍了如何清除布局上的内容？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我刚刚创建的应用程序编写使用的TouchEvent方法在屏幕上的文字。它工作正常。看到这是code

I just create a app for writing the text on Screen using TouchEvent method. It works fine. See this is code

public TouchEventView(Context context, AttributeSet attrs) { super(context, attrs); paint.setAntiAlias(true); paint.setColor(Color.WHITE); paint.setStyle(Paint.Style.STROKE); paint.setStrokeJoin(Paint.Join.ROUND); paint.setStrokeWidth(5f); } @Override protected void onDraw(Canvas canvas) { canvas.drawPath(path, paint); } @Override public boolean onTouchEvent(MotionEvent event) { float x = event.getX(); float y = event.getY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: path.moveTo(x, y); return true; case MotionEvent.ACTION_MOVE: path.lineTo(x, y); break; default: return false; } invalidate(); return true;

之后，我写code清晰的内容布局： -

LinearLayout li = (LinearLayout)findViewById(R.id.linear); li.clearAnimation();

我的logcat

11-18 16:10:18.681: I/System.out(22859): This is a log message 11-18 16:10:18.681: E/Mein Tag(22859): Hello 11-18 16:10:20.581: W/KeyCharacterMap(22859): No keyboard for id 0 11-18 16:10:20.581: W/KeyCharacterMap(22859): Using default keymap: /system/usr/keychars/qwerty.kcm.bin 11-18 16:10:21.721: D/AndroidRuntime(22859): Shutting down VM 11-18 16:10:21.721: W/dalvikvm(22859): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 11-18 16:10:21.731: E/AndroidRuntime(22859): FATAL EXCEPTION: main 11-18 16:10:21.731: E/AndroidRuntime(22859): java.lang.NullPointerException 11-18 16:10:21.731: E/AndroidRuntime(22859): at de.vogella.android.touch.WriteOnScreenActivity.clear(WriteOnScreenActivity.java:47) 11-18 16:10:21.731: E/AndroidRuntime(22859): at de.vogella.android.touch.WriteOnScreenActivity.onOptionsItemSelected(WriteOnScreenActivity.java:38) 11-18 16:10:21.731: E/AndroidRuntime(22859): at android.app.Activity.onMenuItemSelected(Activity.java:2195) 11-18 16:10:21.731: E/AndroidRuntime(22859): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:730) 11-18 16:10:21.731: E/AndroidRuntime(22859): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:143) 11-18 16:10:21.731: E/AndroidRuntime(22859): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:855) 11-18 16:10:21.731: E/AndroidRuntime(22859): at com.android.internal.view.menu.IconMenuView.invokeItem(IconMenuView.java:532) 11-18 16:10:21.731: E/AndroidRuntime(22859): at com.android.internal.view.menu.IconMenuItemView.performClick(IconMenuItemView.java:122) 11-18 16:10:21.731: E/AndroidRuntime(22859): at android.view.View$PerformClick.run(View.java:8816) 11-18 16:10:21.731: E/AndroidRuntime(22859): at android.os.Handler.handleCallback(Handler.java:587) 11-18 16:10:21.731: E/AndroidRuntime(22859): at android.os.Handler.dispatchMessage(Handler.java:92) 11-18 16:10:21.731: E/AndroidRuntime(22859): at android.os.Looper.loop(Looper.java:123) 11-18 16:10:21.731: E/AndroidRuntime(22859): at android.app.ActivityThread.main(ActivityThread.java:4627) 11-18 16:10:21.731: E/AndroidRuntime(22859): at java.lang.reflect.Method.invokeNative(Native Method) 11-18 16:10:21.731: E/AndroidRuntime(22859): at java.lang.reflect.Method.invoke(Method.java:521) 11-18 16:10:21.731: E/AndroidRuntime(22859): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 11-18 16:10:21.731: E/AndroidRuntime(22859): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 11-18 16:10:21.731: E/AndroidRuntime(22859): at dalvik.system.NativeStart.main(Native Method) 11-18 16:22:15.801: I/System.out(23179): This is a log message 11-18 16:22:15.811: E/Mein Tag(23179): Hello

当我preSS清除按钮，我得到空指针异常为这个应用程序。有什么做错了吗？

When i press the clear button, i got Nullpointer Exception for this app. What am doing wrong?

任何人引导我。

推荐答案

我已经得到了答案（ AndroidTechMe ）。我用的onCreate（空）清除内容。感谢队友。

I've got the answer from (AndroidTechMe). I used onCreate(null) to clear the contents. Thanks mate.