Question

我可以在Web开发中将变量设置为类似会话的上下文吗？

以下是我的代码，我将在Android应用程序启动后立即开发一个确认框：

package com.example.alertboxandloadingwidgets;

import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.view.Menu;
import android.widget.Toast;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Boolean result = showConfirmationBox("Are you sure you want to do this",
        this);
    }
    public Boolean showConfirmationBox(String messageToShow, final Context context) {
        // prepare the alert box
        AlertDialog.Builder alertbox = new AlertDialog.Builder(context);
        // set the message to display
        alertbox.setMessage(messageToShow);
        // set a positive/yes button and create a listener
        alertbox.setPositiveButton("Yes",
        new DialogInterface.OnClickListener() {
            // do something when the button is clicked
            public void onClick(DialogInterface arg0, int arg1) {
                Toast.makeText(context,
                    "'Yes' button clicked", Toast.LENGTH_SHORT)
                    .show();
            }
        });
        // set a negative/no button and create a listener
        alertbox.setNegativeButton("No", new DialogInterface.OnClickListener() {
            // do something when the button is clicked
            public void onClick(DialogInterface arg0, int arg1) {
                Toast.makeText(context, "'No' button clicked",
                Toast.LENGTH_SHORT).show();
            }
        });
        // display box
        alertbox.show();
    }
}

但我希望如果单击yes按钮，则必须返回true，如果单击no按钮，则必须返回false。

但我无法这样做，因为onClickListener的返回类型无效。

更新

但问题是我已经使它成为泛型意味着这个方法我必须在CommonUtilities类中编写，其中任何活动都可以使用此方法。所以我必须设置或重置我调用此方法的结果参数的值。

Answer 1

Android对话框是异步的，因此您需要重构代码来处理此问题。我猜你打算做这样的事情：

boolean result = showConfirmation(...);
if(result) {
    //do something
}
else {
    //do something else
}

您可以通过以下方式获得相同的结果：

public class MainActivity extends Activity {
    private boolean result;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        showConfirmationBox("Are you sure you want to do this", this);
    }

    private doOnTrueResult() {
        result = true;
        //do something
    }

    private doOnFalseResult() {
        result = false;
        //do something else
    }

    public void showConfirmationBox(String messageToShow, final Context context) {

        // prepare the alert box
        AlertDialog.Builder alertbox = new AlertDialog.Builder(context);

        // set the message to display
        alertbox.setMessage(messageToShow);

        // set a positive/yes button and create a listener
        alertbox.setPositiveButton("Yes",
        new DialogInterface.OnClickListener() {

            // do something when the button is clicked
            public void onClick(DialogInterface arg0, int arg1) {
                Toast.makeText(context,
                    "'Yes' button clicked", Toast.LENGTH_SHORT)
                    .show();
                doOnTrueResult();
            }
        });

        // set a negative/no button and create a listener
        alertbox.setNegativeButton("No", new DialogInterface.OnClickListener() {

            // do something when the button is clicked
            public void onClick(DialogInterface arg0, int arg1) {
                Toast.makeText(context, "'No' button clicked",
                Toast.LENGTH_SHORT).show();
                doOnFalseResult();
            }
        });

        // display box
        alertbox.show();
    }
}

Answer 2

这就是我总是处理对话框中数据的方式

alertbox.setPositiveButton("Yes",
    new DialogInterface.OnClickListener() {

        // do something when the button is clicked
        public void onClick(DialogInterface arg0, int arg1) {
            Toast.makeText(context,
                "'Yes' button clicked", Toast.LENGTH_SHORT)
                .show();
               myFunction(item);
        }
    });

private void myFunction(int result){
// Now the data has been "returned" (that's not
// the right terminology)
}

同样，对其他Button使用另一个函数

Answer 3

您必须将值从onClickListener传递给全局变量或其他方法。正确识别onClickListener的返回类型为 void 。有关更复杂的解决方案，请查看this post

Answer 4

为结果值创建setter，并将值更改为onClick()方法中的选定值。

让showConfirmationBox无效; - ）

Answer 5

如果功能

public Boolean showConfirmationBox(String messageToShow, final Context context)

需要在主线程中调用，你不能这样做。您永远不会等待主线程上的用户输入。这将导致ANR。

如果可以在后台线程中调用该函数，则可以向主线程发送消息以显示警告框，然后等待结果。充分利用“处理程序”。

Answer 6

你不能这样做，但你可以创建一个布尔变量，如果是则存储为真，如果没有则存储假，然后你可以相应地使用该变量

Answer 7

一种简单的方法可以做到：

public class MainActivity extends Activity {
    public static boolean result;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        showConfirmationBox("Are you sure you want to do this", this);

    }

    public Boolean showConfirmationBox(String messageToShow, final Context context) {
        AlertDialog.Builder alertbox = new AlertDialog.Builder(context);
        alertbox.setMessage(messageToShow);
        alertbox.setPositiveButton("Yes",
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface arg0, int arg1) {
                Toast.makeText(context, "'Yes' button clicked", Toast.LENGTH_SHORT).show();
                MainActivity.result = true;
            }
        });

    // set a negative/no button and create a listener
    alertbox.setNegativeButton("No", new DialogInterface.OnClickListener() {

        // do something when the button is clicked
        public void onClick(DialogInterface arg0, int arg1) {
            Toast.makeText(context, "'No' button clicked",
            Toast.LENGTH_SHORT).show();
            MainActivity.result = false;
        }
    });

    // display box
    alertbox.show();

    }
}

Answer 8

其中一个选项是使用

public Button getButton (int whichButton)
Gets one of the buttons used in the dialog.

this Returns
The button from the dialog, or null if a button does not exist.

有关详细信息，请查看链接http://developer.android.com/reference/android/app/AlertDialog.html

Answer 9

这可能有助于你

public class MainActivity extends Activity {
     Boolean mresult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

          Boolean result = showConfirmationBox("Are you sure you want to do this",this);
          Toast.makeText(getApplicationContext(), ""+result, Toast.LENGTH_LONG).show();


    }

     public Boolean showConfirmationBox(String messageToShow, final Context context) {       

            AlertDialog.Builder alertbox = new AlertDialog.Builder(context);
            // set the message to display
            alertbox.setMessage(messageToShow);
            // set a positive/yes button and create a listener
            alertbox.setPositiveButton("Yes",
            new DialogInterface.OnClickListener() {
                // do something when the button is clicked
                public void onClick(DialogInterface arg0, int arg1) {
                    Toast.makeText(context,
                        "'Yes' button clicked", Toast.LENGTH_SHORT)
                        .show();

                    mresult = true;
                }
            });
            // set a negative/no button and create a listener
            alertbox.setNegativeButton("No", new DialogInterface.OnClickListener() {
                // do something when the button is clicked
                public void onClick(DialogInterface arg0, int arg1) {
                    Toast.makeText(context, "'No' button clicked",
                    Toast.LENGTH_SHORT).show();

                    mresult = false;
                }
            });
            // display box
            alertbox.show();
            return mresult;
        }


}

从Android的onClickListener获取返回值

更新

9 个答案: