我一直在嘗試從 SharedPreferences 作為字符串獲取一個(gè)鍵的值，以便我可以修改連接到片段的布局中的數(shù)據(jù)。這是我的 OneFragment.java 代碼public class OneFragment extends Fragment{private TextView mText;public OneFragment() { // Required empty public constructor}@Overridepublic void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // Inflate the layout for this fragment View view = inflater.inflate(R.layout.fragment_one, container, false); SharedPreferences prefs = getActivity().getSharedPreferences("EID", Context.MODE_PRIVATE); String value = prefs.getString("EID", "0"); mText = (TextView) view.findViewById(R.id.textView2); mText.setText(value); return view; }}該應(yīng)用程序說它在打開時(shí)已停止。我正在調(diào)用來自主要活動(dòng)的片段。工作室怎么說：E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.dell.tab2, PID: 3857 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.dell.tab2/com.example.dell.tab2.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.SharedPreferences android.content.Context.getSharedPreferences(java.lang.String, int)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2548) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
2 回答
翻閱古今
TA貢獻(xiàn)1780條經(jīng)驗(yàn) 獲得超5個(gè)贊
如果您無法在 Fragment 中獲取該值，則可以從您的 Activity 中獲取該值。調(diào)用片段：
String value = ((YourActivityName)getActivity()).getValuePreference();
并在您的活動(dòng)中添加方法：
public String getValuePreference(){
SharedPreferences preferences = getSharedPreferences("SharedPreferences", Context.MODE_PRIVATE);
return preferences.getString("EID", "0");
}
心有法竹
TA貢獻(xiàn)1866條經(jīng)驗(yàn) 獲得超5個(gè)贊
試試這個(gè)：
在片段中添加以下代碼
Context context;
@Override
public void onAttach(Context context) {
super.onAttach(context);
this.context = context;
}
在onCreateView替換getActivity()用context
SharedPreferences prefs = context.getSharedPreferences("EID", Context.MODE_PRIVATE);
String value = prefs.getString("EID", "0");
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