主界面监听返回键，退出程序

/** * 通用退出程序的提示框 *  * @param context */public static void exit_dialog(Context context) {AlertDialog.Builder builder = new Builder(context);builder.setMessage("确定要退出吗?");builder.setTitle("提示");builder.setIcon(android.R.drawable.ic_dialog_alert);builder.setPositiveButton("确认", new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog, int which) {dialog.dismiss();MyApplication.getInstance().exit();}});builder.setNegativeButton("取消",new android.content.DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog, int which) {dialog.dismiss();}});builder.create().show();}

其中MyApplication.getInstance().exit();的MyApplication类参照MyApplication.java