我正在尝试将TextWatcher方法添加到通过导航抽屉加载的片段中:
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
testMethod();
}
public void testMethod() {
EditText tv_filter = (EditText) getActivity().findViewById(R.id.editText);
tv_filter.addTextChangedListener(new TextWatcher() {
public void afterTextChanged(Editable s) {
}
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
public void onTextChanged(CharSequence s, int start,
int before, int count) {
Toast.makeText(getActivity(), "INPUT TRACKED", Toast.LENGTH_SHORT).show();
}
});
}
问题是,无论何时加载此片段,应用程序都会崩溃并显示以下logcat消息:
08-26 12:00:26.553 12842-12842/fest.test.dk.fest E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: fest.test.dk.fest, PID: 12842
java.lang.NullPointerException
at fest.test.dk.fest.menuFragment.testMethod(menuFragment.java:74)
at fest.test.dk.fest.menuFragment.onCreate(menuFragment.java:66)
at android.support.v4.app.Fragment.performCreate(Fragment.java:1766)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:917)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:458)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
通常logcat对于错误会非常精确,但我无法确切地知道这个错误意味着什么。
答案 0 :(得分:0)
getActivity()可能为null。转移testMethod的调用。覆盖片段中的onAttach并从那里调用它。再次阅读片段生命周期。