Question

我有一个启动对话框的片段。在对话框中有一个文本视图和一个按钮。当您按下对话框内的按钮时，它应从文本字段中获取值并将其发送到异步任务。

当我尝试检索文本字段的值时，我的应用程序强行关闭：

public class ListPage extends Fragment {

    String beerID = "";
    String userID = "";

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

        //set layout here
        View v = inflater.inflate(R.layout.frag_listpage, container, false);
        setHasOptionsMenu(true);
        getActivity().setTitle("Your Lists");

        //get user information
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
        String userName = prefs.getString("userName", null);
        userID = prefs.getString("userID", null);
        beerID = prefs.getString("beerID", null);




        //todo: get lists and add checkboxes with onclick



        Button bt2 = (Button)v.findViewById(R.id.buttonAddList);

        bt2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {

                // Create custom dialog object
                final Dialog dialog = new Dialog(getActivity());
                // Include dialog.xml file
                dialog.setContentView(R.layout.listdialog);
                // Set dialog title
                dialog.setTitle("Create a List");

                // set values for custom dialog components - text, image and button
                TextView text = (TextView) dialog.findViewById(R.id.textDialog);


                dialog.show();

                Button declineButton = (Button) dialog.findViewById(R.id.declineButton);
                // if decline button is clicked, close the custom dialog
                declineButton.setOnClickListener(new OnClickListener() {
                    @Override
                    public void onClick(View v) {

                        //todo: run async task to save text field value as a list

                        //get value from text field
                        EditText mEdit   = (EditText)v.findViewById(R.id.listName);

                        String lName = mEdit.getText().toString();
                        try {
                            lName = URLEncoder.encode(lName, "UTF-8");
                        } catch (UnsupportedEncodingException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }


                        //run async task with beerID, userID and lName
                        //log in url
                        String url = "myURL;
                        Log.d("registerURL", url);
                        //async task for getting json
                        new AddList(getActivity()).execute(url);


                        // Close dialog
                        dialog.dismiss();
                    }
                });


            }

        });




        // Inflate the layout for this fragment
        return v;

    }

错误是：

03-26 16:06:19.340    7659-7659/com.beerportfolio.beerportfoliopro E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.NullPointerException
            at com.beerportfolio.beerportfoliopro.ListPage$1$1.onClick(ListPage.java:87)
            at android.view.View.performClick(View.java:4280)
            at android.view.View$PerformClick.run(View.java:17984)
            at android.os.Handler.handleCallback(Handler.java:730)
            at android.os.Handler.dispatchMessage(Handler.java:92)
            at android.os.Looper.loop(Looper.java:158)
            at android.app.ActivityThread.main(ActivityThread.java:5789)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:843)
            at dalvik.system.NativeStart.main(Native Method)

第87行是：

String lName = mEdit.getText().toString();

Answer 1

您以错误的方式找到了EditText。取代

EditText mEdit   = (EditText)v.findViewById(R.id.listName);

与

EditText mEdit   = (EditText)dialog.findViewById(R.id.listName);

v是点击的按钮，因此无法找到内部的EditText。

编辑文本toString抛出空指针

1 个答案: