Question

在我的主课程中，我有一个按钮来调用一个显示带有edittext的对话框的类。我的问题是这样 - 主要活动在第一次运行时没有得到edittext值，如果我第二次运行它，我得到旧的edittext值。

似乎主活动类执行完整的代码块并返回存储在类中的先前值，我尝试了很多方法，包括共享首选项。

MainActivity.java

public class MainActivity extends Activity {
    EditText comment_et,input_et;
    Spinner spinner;
    Button addbutton,reportbut;
    String input_string,date,time,comment,item;
    TextView date_tv,time_tv;
    String temp[];
    Datas datatemp;
    String savedinput;

    ArrayList<String> list = new ArrayList<String>();


    ArrayAdapter<String> adapter;
    DatabaseHandler db = new DatabaseHandler(this);

    @Override
    protected void onCreate(Bundle savedInstanceState) 
{

        SharedPreferences prefs = getSharedPreferences("myprefs", 0);
        savedinput=  prefs.getString("KEY_SAVEDINPUT","");

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        spinner = (Spinner)findViewById(R.id.spin1);
        input_et = (EditText)findViewById(R.id.input_et);
        addbutton = (Button)findViewById(R.id.addbutton);
        reportbut = (Button)findViewById(R.id.report);

        comment_et = (EditText)findViewById(R.id.comment_et);
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, list);
        date_tv = (TextView)findViewById(R.id.date_tv);
        time_tv = (TextView)findViewById(R.id.time_tv);

        final Calendar c = Calendar.getInstance();
        int mYear = c.get(Calendar.YEAR);
        int mMonth = c.get(Calendar.MONTH);
        int mDay = c.get(Calendar.DAY_OF_MONTH);
        int mHour = c.get(Calendar.HOUR_OF_DAY);
        int mMinute = c.get(Calendar.MINUTE);

        date = ""+mDay+"/"+mMonth+1+"/"+mYear;
        time = ""+mHour+":"+mMinute;
        date_tv.setText(date);
        time_tv.setText(time);

        int max_id = db.getDatasCount();

        for(int i = 1; i<max_id+1 ;i++)
         {          

        datatemp = db.getItemOnly(i);
        String s = datatemp._item.toString();
        list.add("   "+ s);
         }


        addbutton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                AlertDialogManager alert = new AlertDialogManager();

                alert.showAlertDialog(MainActivity.this, "Enter Item",
                        "Please enter the spinner item",
                        true);
                System.out.println("main : " +savedinput);

            }   

        });



            reportbut.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {
                    Intent i = new Intent(getApplicationContext(), ListviewActivity.class);
                    startActivity(i);

                }

            });


        spinner.setAdapter(adapter);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        spinner.setOnItemSelectedListener(new OnItemSelectedListener() {

            @Override
            public void onItemSelected(AdapterView<?> parent, View view,
                    int position, long id) {

                item = parent.getItemAtPosition(position).toString();

            }

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {


            }
        });

        Button submit = (Button)findViewById(R.id.save);
        submit.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) 
            {

                 comment  = comment_et.getText().toString();

                    System.out.println("comment:"+comment);

                /**
                 * CRUD Operations
                 * */
                // Inserting Contacts
                Log.d("Insert: ", "Inserting ..");
                db.addData(new Datas(item, comment, date, time));
                Toast.makeText(getApplicationContext(), "Data Submitted Successfully",
                Toast.LENGTH_LONG).show();
                // Reading all contacts
                Log.d("Reading: ", "Reading all contacts..");
                List<Datas> datas = db.getAllDatas();       

                for (Datas d : datas) {
                    String log = "Id: "+d.getID()+" ,Item: " + d.getItem() + " ,Comment: " + d.getComment() + " ,Date: " + d.getDate() + ",Comment: " + d.getTime();
                        // Writing Contacts to log
                Log.d("Item: ", log);
                }
            }
        });
}

    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

}

AlertDialogManager.java

public class AlertDialogManager {
    /**
     * Function to display simple Alert Dialog
     * @param context - application context
     * @param title - alert dialog title
     * @param message - alert message
     * @param status - success/failure (used to set icon)
     *               - pass null if you don't want icon
     * */
    String savedinput;
    public void showAlertDialog(final Context context, String title, String message,
            Boolean status) 
    {
        AlertDialog alertDialog = new AlertDialog.Builder(context).create();

        // Setting Dialog Title
        alertDialog.setTitle(title);

        // Setting Dialog Message
        alertDialog.setMessage(message);

        //setting input
         final EditText input = new EditText(context);
         alertDialog.setView(input);

         // saving input to a string
         savedinput = input.getText().toString();
         System.out.println(savedinput);

        if(status != null)
            // Setting alert dialog icon
            alertDialog.setIcon((status) ? R.drawable.success : R.drawable.fail);

        // Setting OK Button
        alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                savedinput = input.getText().toString();

                SharedPreferences prefs = context.getSharedPreferences("myprefs", 0);
                SharedPreferences.Editor editor =prefs.edit();
                editor.putString("KEY_SAVEDINPUT", savedinput);
                editor.commit();                
                System.out.println("from class "+savedinput);
            }
        });



        // Showing Alert Message
        alertDialog.show();

    }

    String getItem()
    {
        return savedinput;
    }
}

这是我的logcat，只是为了进一步澄清

02-01 13:48:43.372: I/System.out(897): main : firstexecute
02-01 13:48:46.942: W/KeyCharacterMap(897): No keyboard for id 0
02-01 13:48:46.942: W/KeyCharacterMap(897): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
02-01 13:48:49.532: I/System.out(897): from class secondexecute

Answer 1

这里有几个问题。

您不应该在savedValue中阅读onCreate，只有在您实际使用它时才应该这样做。见@ρяσѕρєяK答案。
alert.showAlertDialog无阻止。因此，在显示对话框后，执行行System.out.println("main : " + savedInput);。 不等待输入。因此，您应该在对话框的确定按钮上保存到共享首选项旁边调用其他一些操作。此操作应调用用户在对话框中输入一些文本后应发生的逻辑。

<强>更新

public void showAlertDialog(final Context context, String title, String message,
                            Boolean status, final Spinner spinner) 
{
    AlertDialog alertDialog = new AlertDialog.Builder(context).create();

    // Setting Dialog Title
    alertDialog.setTitle(title);

    // Setting Dialog Message
    alertDialog.setMessage(message);

    //setting input
     final EditText input = new EditText(context);
     alertDialog.setView(input);

     // saving input to a string
     savedinput = input.getText().toString();
     System.out.println(savedinput);

    if(status != null)
        // Setting alert dialog icon
        alertDialog.setIcon((status) ? R.drawable.success : R.drawable.fail);

    // Setting OK Button
    alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            savedinput = input.getText().toString();
            // do whatever you want with spinner and savedInput here.
        }
    });

    // Showing Alert Message
    alertDialog.show();
 }

点击以显示对话框：

alert.showAlertDialog(MainActivity.this, "Enter Item",
     "Please enter the spinner item",
     true, (Spinner) findViewById(R.id.spin1));

更新2 显然，您需要将新项添加到您的微调器适配器。为此，您可以创建所有项目的列表，并将此列表与适配器一起传递给对话框。当用户输入字符串并按OK按钮时，onClick方法会将此字符串添加到列表中并调用notifyDataSetChanged来更新UI：

在MainActivity：

List<String> spinnerItems;

在onCreate：

spinnerItems = new ArrayList<String>();
adapter = enw ArrayAdapter<String>(this, 0, spinnerItems);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);

将spinnerItems和adapter传递给showAlertDialog：

alert.showAlertDialog(MainActivity.this, "Enter Item",
     "Please enter the spinner item",
     true, spinnerItems, adapter);

最后添加文本到列表并通知适配器：

alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int which) {
        savedinput = input.getText().toString();
        spinnerItems.add(savedInput);
        adapter.notifyDataSetChanged();
    }
});

Answer 2

您需要在按钮点击而不是onCreate上获取最新值，以便从SharedPreferences获取最新值：

addbutton.setOnClickListener(new View.OnClickListener() {

        @Override
         public void onClick(View v) {
           AlertDialogManager alert = new AlertDialogManager();

           alert.showAlertDialog(MainActivity.this, "Enter Item",
                        "Please enter the spinner item",
                        true);
           savedinput=  prefs.getString("KEY_SAVEDINPUT",""); //<<< get value here
           System.out.println("main : " +savedinput);

       }   

   });

或者您将尝试从onResume of Activity获取价值

Answer 3

这个

savedinput = input.getText().toString();

在运行时进行评估。不是在你致电getItem()时。在这种情况下，在显示警报之前，您将获得的价值就是它。

同样的逻辑

savedinput=  prefs.getString("KEY_SAVEDINPUT","");

无法访问其他类的值

3 个答案: