如何从片段活动调用MainActive变量

Question

我刚接触Android，有一个带有片段的选项卡布局，我有一个编辑文本字段，它是在我的父活动中声明的，我想检查编辑文本字段是否为空，是否来自片段。我该怎么做呢？这是我做的，但它显示了错误。这是我的主要活动编辑文本字段：

search_edit_text = (FloatingEditText)findViewById(R.id.edt_missile_number);
        search_edit_text.setInputType(InputType.TYPE_CLASS_NUMBER);
        search_edit_text.setGravity(Gravity.CENTER);
        search_edit_text.setCursorVisible(false);
        search_edit_text.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                search_edit_text.setCursorVisible(true);

            }
        });

这是我的片段活动：

public class Manual_AC_Fuse_ckt extends Fragment {


    static Manual manual_child;    //MANUAL----->PARENT CLASS NAME


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {



         Root_view = inflater.inflate(R.layout.manualmode_ac_fuse_ckt, null);
         manual_child = new Manual();
        (CheckBox)Root_view.findViewById(check_box_count_fuse_after_cnc[i]);

        registerForContextMenu(table_fuse_afer_cnc);
        return Root_view;


    }
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v,
            ContextMenuInfo menuInfo) {
        menu.setHeaderTitle("MANUAL MODE : CONNECTION");
        menu.add(1, v.getId(), 0, "TEST  ");
        menu.add(1, v.getId(), 0, "SELECT ALL  ");
        menu.add(1, v.getId(), 0, "DESELECT ALL  ");
        super.onCreateContextMenu(menu, v, menuInfo);
    }
    @Override
    public boolean onContextItemSelected(MenuItem item) {
        if(item.getTitle()=="TEST  ")
        {

            if(manual_child.search_edit_text.equals(""))
            {
                Toast.makeText(getActivity(),"Empty Message",Toast.LENGTH_LONG).show();
            }

}
}

这是我的日志：

01-02 07:27:25.830: E/AndroidRuntime(28243): FATAL EXCEPTION: main
01-02 07:27:25.830: E/AndroidRuntime(28243): java.lang.NullPointerException
01-02 07:27:25.830: E/AndroidRuntime(28243):    at com.developer.milanandroid.Manual_AC_Fuse_ckt.onContextItemSelected(Manual_AC_Fuse_ckt.java:120)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.support.v4.app.Fragment.performContextItemSelected(Fragment.java:1909)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.support.v4.app.FragmentManagerImpl.dispatchContextItemSelected(FragmentManager.java:2058)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:359)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at com.android.internal.policy.impl.PhoneWindow$DialogMenuCallback.onMenuItemSelected(PhoneWindow.java:3644)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:152)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at com.android.internal.view.menu.MenuDialogHelper.onClick(MenuDialogHelper.java:167)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:941)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.widget.AdapterView.performItemClick(AdapterView.java:298)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.widget.AbsListView.performItemClick(AbsListView.java:1100)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.widget.AbsListView$PerformClick.run(AbsListView.java:2788)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.widget.AbsListView$1.run(AbsListView.java:3473)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.os.Handler.handleCallback(Handler.java:730)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.os.Handler.dispatchMessage(Handler.java:92)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.os.Looper.loop(Looper.java:137)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at android.app.ActivityThread.main(ActivityThread.java:5103)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at java.lang.reflect.Method.invokeNative(Native Method)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at java.lang.reflect.Method.invoke(Method.java:525)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
01-02 07:27:25.830: E/AndroidRuntime(28243):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

您可以在片段中调用主要活动变量，如下所示：

EditText edt = (EditText)getActivity().findViewById(R.id.edtSearch);

Answer 2

这里有两点。1.可以使用FloatingEditText editText=（FloatingEditText）（（MainActivity.this）getActivity（）。findViewById（R.id.edt\u导弹编号）；2.使用if（item.getTitle（）。等于（“测试”）条件。

Answer 3

为此，您应该使用接口。您可以在活动实现的片段中创建一个接口。这是与活动视图通信的更好方式。

请参阅这篇文章以获取有关如何做到这一点的参考：Android:on-fragment interaction Listener出错