以下方法顯示NullPointerException。我無法理解下面的代碼有什麼問題。該文件存儲在BufferedWriter中的NullPointerException
public class Mtx extends Activity {
public void ConfWrite() {
try {
BufferedWriter buf = new BufferedWriter(new FileWriter(getFilesDir()+"\\file.java"));
buf.write("Hello Android");
buf.newLine();
buf.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
堆棧跟蹤輸出
02-10 13:11:18.365: WARN/System.err(7179): java.lang.NullPointerException
02-10 13:11:18.396: WARN/System.err(7179): at android.content.ContextWrapper.getFilesDir(ContextWrapper.java:178)
02-10 13:11:18.419: WARN/System.err(7179): at mediatronix.HAT.Mtx.ConfWrite(Mtx.java:19)
02-10 13:11:18.425: WARN/System.err(7179): at mediatronix.HAT.MainMenu.onCreate(MainMenu.java:46)
02-10 13:11:18.437: WARN/System.err(7179): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-10 13:11:18.485: WARN/System.err(7179): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
02-10 13:11:18.495: WARN/System.err(7179): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
02-10 13:11:18.505: WARN/System.err(7179): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
02-10 13:11:18.525: WARN/System.err(7179): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
02-10 13:11:18.545: WARN/System.err(7179): at android.os.Handler.dispatchMessage(Handler.java:99)
02-10 13:11:18.555: WARN/System.err(7179): at android.os.Looper.loop(Looper.java:123)
02-10 13:11:18.585: WARN/System.err(7179): at android.app.ActivityThread.main(ActivityThread.java:4627)
02-10 13:11:18.616: WARN/System.err(7179): at java.lang.reflect.Method.invokeNative(Native Method)
02-10 13:11:18.625: WARN/System.err(7179): at java.lang.reflect.Method.invoke(Method.java:521)
02-10 13:11:18.665: WARN/System.err(7179): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-10 13:11:18.675: WARN/System.err(7179): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-10 13:11:18.695: WARN/System.err(7179): at dalvik.system.NativeStart.main(Native Method)
感謝
是方法getFilesDir()正常工作 – jeet 2012-02-10 07:24:17
我不知道,怎麼我可以嗎 ? – Riskhan 2012-02-10 07:28:54
發佈堆棧跟蹤和getFilesDir()方法的內容(這很可能是問題的根源)。 – 2012-02-10 07:32:43