Question

我正在尝试从对话框加载一些SharedPreferences数据（复选框状态）。我有以下代码：

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.proficiency_dialog, null);
        getDialog().getWindow().requestFeature(Window.FEATURE_NO_TITLE);
        updateProficiency = (Button) view.findViewById(R.id.update_proficiency);
        updateProficiency.setOnClickListener(this);
        cancelProficiency = (Button) view.findViewById(R.id.cancel_proficiency);
        cancelProficiency.setOnClickListener(this);
        STR_Prof_checkbox = (CheckBox) getDialog().findViewById(R.id.STR_save_checkbox);
        loadSavedPreferences();
        setCancelable(false);
        return view;
    }

    public void loadSavedPreferences() {
        SharedPreferences sharedPreferences = PreferenceManager
                .getDefaultSharedPreferences(getContext());
        boolean STRProfCheckBoxValue = sharedPreferences.getBoolean("STR_Save_CheckBox_Value", false);
        if (STRProfCheckBoxValue) {
            STR_Prof_checkbox.setChecked(true);
        } else {
            STR_Prof_checkbox.setChecked(false);
        }
    }

但是，我在loadSavedPreferences()方法上收到空指针异常。我错过了什么导致错误？

logcat的：

01-18 01:51:55.273 26730-26730/com.oozhangem.dd5echaracter E/AndroidRuntime: FATAL EXCEPTION: main
 Process: com.oozhangem.dd5echaracter, PID: 26730
 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.CheckBox.setChecked(boolean)' on a null object reference
     at com.oozhangem.dd5echaracter.ProficiencyDialog.loadSavedPreferences(ProficiencyDialog.java:47)
     at com.oozhangem.dd5echaracter.ProficiencyDialog.onCreateView(ProficiencyDialog.java:35)
     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1248)
     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1613)
     at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
     at android.os.Handler.handleCallback(Handler.java:739)
     at android.os.Handler.dispatchMessage(Handler.java:95)
     at android.os.Looper.loop(Looper.java:135)
     at android.app.ActivityThread.main(ActivityThread.java:5294)
     at java.lang.reflect.Method.invoke(Native Method)
     at java.lang.reflect.Method.invoke(Method.java:372)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)

Answer 1

替换

SharedPreferences preferences = this.getActivity().getSharedPreferences("pref", Context.MODE_PRIVATE);

用

SharedPreferences pref = getActivity().getPreferences(0);

或者

STR_Prof_checkbox

同时将STR_Prof_checkbox = (CheckBox) view.findViewById(R.id.STR_save_checkbox);的引用替换为以下内容。

{{1}}

从Dialog CheckBox访问SharedPreferences

1 个答案: