Question

我为简单的“警告对话框”编写了以下代码，但未显示“警告对话框”。 API：26

 @Override
    public void onBackPressed() {
        super.onBackPressed();

    AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
    builder.setMessage("Are You sure to Exit?")
            .setTitle("Exit")
            .setCancelable(false)
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    MainActivity.super.onBackPressed();
                }
            })
            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {

                }
            });

    AlertDialog alert = builder.create();
    alert.show();
}

我是android的新手，并且正在测试它的功能。我已经用30分钟的时间对该小代码进行了调试，并在模拟器和外部电话中使用了不同的电话，但是失败了。然后，我决定将此代码放到stackoverflow上。

Answer 1

使用此代码以程序方式退出或关闭应用程序

@Override
    public void onBackPressed() {
        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
        alertDialogBuilder.setTitle("Exit Application?");
        alertDialogBuilder
                .setMessage("Click yes to exit!")
                .setCancelable(false)
                .setPositiveButton("Yes",
                        new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                                moveTaskToBack(true);
                                android.os.Process.killProcess(android.os.Process.myPid());
                                System.exit(1);
                            }
                        })

                .setNegativeButton("No", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {

                        dialog.cancel();
                    }
                });

        AlertDialog alertDialog = alertDialogBuilder.create();
        alertDialog.show();
    }

Answer 2

希望此代码可以为您提供帮助！

 @Override
    public void onBackPressed()
    {
         AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
        builder.setMessage("Are You sure to Exit?")
                .setTitle("Exit")
                .setCancelable(false)
                .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        this.finish(); //OR super.onBackPressed(); or whatever u want

                    }
                })
                .setNegativeButton("No", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {

                    }
                });

        AlertDialog alert = builder.create();
        alert.show();
    }

Answer 3

删除super.onBackPressed();

@Override
public void onBackPressed() {
    AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
    builder.setMessage("Are You sure to Exit?")
            .setTitle("Exit")
            .setCancelable(false)
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    MainActivity.super.onBackPressed();
                }
            })
            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {

                }
            });

    AlertDialog alert = builder.create();
    alert.show();
}

Answer 4

如果可以使用内部警报对话框进行返回，则在不给出答案时会返回。您应使用以下代码。

 public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            exitByBackKey();

            //moveTaskToBack(false);

            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

    protected void exitByBackKey() {

        AlertDialog alertbox = new AlertDialog.Builder(this)
                .setMessage("Do you want to exit application?")
                .setPositiveButton("Yes", new DialogInterface.OnClickListener() {

                    // do something when the button is clicked
                    public void onClick(DialogInterface arg0, int arg1) {

                        finish();
                        //close();


                    }
                })
                .setNegativeButton("No", new DialogInterface.OnClickListener() {

                    // do something when the button is clicked
                    public void onClick(DialogInterface arg0, int arg1) {
                    }
                })
                .show();

    }

AlertDialog OnBackPressed（）不能正常工作

4 个答案: