我试图从一个类继承一个函数,但它返回NullPointerException
. 有人可以帮忙吗?
这是我尝试继承的功能Main.java
。该功能在Main.java
.
public void readData() {
String readString = "";
try {
FileInputStream fIn = openFileInput("user.txt");
InputStreamReader isr = new InputStreamReader(fIn);
BufferedReader buffreader = new BufferedReader(isr);
readString = buffreader.readLine();
isr.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
telephonyManager.listen(myPhoneStateListener,
PhoneStateListener.LISTEN_CALL_STATE);
}
这是我另一堂课的编码:
Main main =new Main();
main.readData();
错误日志:
04-16 02:58:23.812: E/AndroidRuntime(8125): java.lang.NullPointerException
04-16 02:58:23.812: E/AndroidRuntime(8125): at android.content.ContextWrapper.openFileInput(ContextWrapper.java:167)
04-16 02:58:23.812: E/AndroidRuntime(8125): at com.test.Main.readData(Main.java:176)