android - 无法设置PositiveButton

Question

如果 GPS 关闭，我想在启动器 Activity 之前应用程序启动后立即显示带有两个按钮“启用 GPS”和“取消”的对话框，否则如果 GPS 打开，启动器 Activity 将打开。当用户单击“启用 GPS”，它将进入 GPS 设置，当用户单击“取消”时，我想显示另一个标题为“如何使用应用程序”的对话框，按钮为“确定”，当用户单击“确定”时，我希望启动器 Activity 被打开。为此，我使用以下代码:

    if (!isGPSEnabled) {
        // no GPS provider is enabled
        // Creating the Dialog box
        AlertDialog alertDialog = new AlertDialog.Builder(MainActivity.this)
                .create();
        alertDialog.setTitle("Settings");
        alertDialog.setMessage("Enable GPS for accessing the Application");
        alertDialog.setButton("GPS Settings",
                new DialogInterface.OnClickListener() {
                    // creating Button i.e GPS Setting in the Dialog Box
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub

                        startActivity(new Intent(
                                android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));

                    }
                });
        alertDialog.show();
        // creating Button i.e Cancel in the Dialog Box
        alertDialog.setButton2("Cancel",
                new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub
                        // Creating another Dialog when "Cancel" is pressed
                        AlertDialog whencancelpressed = new AlertDialog.Builder(
                                MainActivity.this).create();
                        whencancelpressed.setTitle("How to use the app");
                        whencancelpressed
                                .setMessage("Enter the contacts to whom you want to send the message.Double tap power button in emergency");
                        whencancelpressed.setButton("Ok",
                                new DialogInterface.OnClickListener() {
                                    @Override
                                    public void onClick(
                                            DialogInterface dialog,
                                            int which) {
                                        // TODO Auto-generated method stub
                                        Intent pressedokay = new Intent(
                                                getApplicationContext(),
                                                MainActivity.class);
                                        startActivity(pressedokay);
                                    }
                                });
                        whencancelpressed.show();
                    }
                });

    } else {
        // GPS provider is enabled
    }

我面临的问题是，我无法显示“取消”按钮，在完成几个教程后，我尝试将 setButton 更改为 setPositiveButton，eclipse 显示错误。

Answer 1

此代码可 100% 正常工作，只要您喜欢就可以了。 c 作为上下文传递的所有这些。在您的 Activity 中声明这一点，并将 Activity 名称替换为您的 Activity 名称:

上下文 c = ActivityName.this;

  AlertDialog.Builder builder = new AlertDialog.Builder(c);

            builder.setTitle(R.string.confirm);
            builder.setMessage(R.string.deleteConfirm);

            builder.setPositiveButton(R.string.deleteBtnTxt,

            new DialogInterface.OnClickListener() {

                public void onClick(DialogInterface dialog, int which) {
                      startActivity(new Intent(
                            android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));

                    dialog.dismiss();
                }

            });

            builder.setNegativeButton(R.string.no,
                    new DialogInterface.OnClickListener() {

                        @Override
                        public void onClick(DialogInterface dialog,
                                int which) {
                            dialog.dismiss();
                        }
                    });

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