如何从单独类的对话框中返回值

Question

I want to create a function that shows a dialog with 2 buttons on screen and return 1 if user pressed OK and 0 if user pressed Cancel.

public class CDlg {

static int ShowConfirm(String caption, String msg, Context context) {
    int rez;
    AlertDialog.Builder delAllDialog = new AlertDialog.Builder(context);
    delAllDialog.setTitle(caption);

    TextView dialogTxt_id = new TextView(context);
    LayoutParams dialogTxt_idLayoutParams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
    dialogTxt_id.setLayoutParams(dialogTxt_idLayoutParams);
    dialogTxt_id.setText(msg);
    LinearLayout layout = new LinearLayout(context);
    layout.setOrientation(LinearLayout.VERTICAL);
    layout.addView(dialogTxt_id);
    delAllDialog.setView(layout);

    delAllDialog.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface arg0, int arg1) {
            rez = 1;
        }
    });

    delAllDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface arg0, int arg1) {
            rez = 0;
        }
    });

    delAllDialog.show();
    return rez;
}

}

I am now shure that I am doing right because I do not know how to pass a result from unner class to outer one. There is a error message

Cannot refer to a non-final variable rez inside an inner class defined in a different method

So as a result I want to use that function something like this:

if (CDlg.ShowConfirm("User confirmation","Delete?",this)==1){
        ...
}

Answer 1

You can't do this like that. ShowConfirm can only show the dialog. When the user clicks either the OK or Cancel button, only then you can execute what you want:

public class CDlg {
    void ShowConfirm(String caption, String msg) {
        AlertDialog.Builder delAllDialog = new AlertDialog.Builder(this);
        delAllDialog.setTitle(caption);

        TextView dialogTxt_id = new TextView(this);
        LayoutParams dialogTxt_idLayoutParams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        dialogTxt_id.setLayoutParams(dialogTxt_idLayoutParams);
        dialogTxt_id.setText(msg);
        LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.VERTICAL);
        layout.addView(dialogTxt_id);
        delAllDialog.setView(layout);

        delAllDialog.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface arg0, int arg1) {
                handleButtonClick(1);
            }
        });

        delAllDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface arg0, int arg1) {
                handleButtonClick(2);
            }
        });

        delAllDialog.show();
    }

    void handleButtonClick(int rez) {
        switch(rez) {
            case 1: ..... break;
            case 2: ..... break;
            .....
        }
    }
}

The if (CDlg.ShowConfirm("User confirmation","Delete?",this)==1) statement is useless in Android here, since the ShowConfirm will not wait until the user presses a button.

Instead just call ShowConfirm("User confirmation","Delete?"); an implement the appropriate code in the onClick s.

Answer 2

If you want to code in the spirit of Android, you should actually use startActivityForResult. Look at the linked answer for details how it should work. ( here is the documentation )

Answer 3

Define a static variable in the class you want, for example I will define in MyAuxiliaryClass.java:

public static USER_DECISION = -1;

Whenever you choose an option, then you do the following:

if (//Desicion == OK) {
MyAuxiliaryClass.USER_DECISION = 1;
} else (//Decision == NOT OK){
MyAuxiliaryClass.USER_DECISION = 2;
}

Since you are changing this static variable, then you can get the value 1 or 2 in another class. Hope it helps. Best regards.

Answer 4

Make rez an attribute instead of a local variable. As your method is static , the attribute should be too. This means moving the definition outside the method.

public class CDlg {

   static int rez;

   static int ShowConfirm(String caption, String msg, Context context) {
   ...

In the inner classes, you need to refer to the CDlg class

   public void onClick(DialogInterface arg0, int arg1) {
        CDlg.rez = 1;
   }

As a side note, it is strange that you use an static method for this. One of the mistakes of the people new to Java/OOP is to abuse static code, that feels more like C was. Maybe you want to reconsider your code.