Question

我有一个显示评级栏的警报。

LayoutInflater rating = LayoutInflater.from(RatingActivity.this);
            final View v = rating.inflate(R.layout.rating_layout, null);

            AlertDialog.Builder adb = new AlertDialog.Builder(RatingActivity.this);
            adb.setTitle("Rate us!);
            adb.setView(v);
            AlertDialog ratingbar = adb.create();

final RatingBar cleanbar = (RatingBar) ratingbar.findViewById(R.id.clealiness);

当我触发onclick侦听器时，它显示NULL POINTER EXCEPTION。和第二行错误表示getNumStars（）行中的错误。之后强制关闭。

adb.setPositiveButton("Rate", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
    //this line error. means they cant get the rating value?
final String cleaninput = Integer.toString(cleanbar.getNumStars());

我可以通过其他方式获得评级栏的价值吗？我见过很少像ratingBar.getRating（）; ratingBar.getNumStars（）;

所有这些都无法工作......即使我将值直接放入int。

final int cleaninput = (int) cleanbar.getRating();  //fails

EDITTED（SOLVE）::

final RatingBar cleanbar = (RatingBar)v.findViewById(R.id.clealiness);

我将评级栏替换为v而不是它的工作原理！我不知道原因＆gt;。＆lt;

Answer 1

我认为你的问题是：

final RatingBar cleanbar = (RatingBar) ratingbar.findViewById(R.id.clealiness);

它不会正确初始化RatingBar，因为你没有从Activity的布局（包含RatingBar）初始化RatingBar，这就是你在

获得 NPE 的原因

cleanbar.getNumStars() // cleanbar is assigned as null

将其更改为

final RatingBar cleanbar = (RatingBar) findViewById(R.id.clealiness);

现在应该可以了。

更新

LayoutInflater rating = LayoutInflater.from(RatingActivity.this);
final View ratingView = rating.inflate(R.layout.rating_layout, null);

AlertDialog.Builder adb = new AlertDialog.Builder(RatingActivity.this);               
adb.setTitle("Rate us!);
adb.setView(ratingView);

AlertDialog ratingbar = adb.create();

现在正确获取价值：

RatingBar cleanbar = (RatingBar) ratingView.findViewById(R.id.clealiness);

您需要将RatingBar与View分配给您。

现在它应该有效：

final int cleaninput = (int) cleanbar.getRating();

无法从AlertBog中的RatingBar获取值

1 个答案:

更新