NumberPicker onValueChange未被调用

Question

你好，我在实现使用DialogFragment的NumberPicker时遇到了一些困难。我有一些代码，如果用户按下按钮，将提示用户通过AlertDialog选择一个数字。我能够显示Dialog，但是当我通过Picker选择一个数字时，我无法保存这个值。根据我的调试，似乎从未调用过onValueChange方法。知道为什么吗？下面是我的numberPicker DialogFragment代码

public static class numberPickerDialog extends DialogFragment
        implements NumberPicker.OnValueChangeListener {


    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState){

        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        final NumberPicker picker = new NumberPicker(getActivity());
        picker.setMinValue(1);
        picker.setMaxValue(60);
        picker.setValue(25);
        picker.setWrapSelectorWheel(false);

        builder.setMessage("Set Study Time")
                .setPositiveButton("Set", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        //
                    }
                })
                .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        //cancel
                    }
                });

        final FrameLayout parent = new FrameLayout(getActivity());
        parent.addView(picker, new FrameLayout.LayoutParams(
                FrameLayout.LayoutParams.WRAP_CONTENT,
                FrameLayout.LayoutParams.WRAP_CONTENT,
                Gravity.CENTER));
        builder.setView(parent);

        Dialog dialog = builder.create();
        return dialog;
    }

    @Override
    public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
        String toastMessage = "test";
        Toast toast = Toast.makeText(getActivity(), toastMessage, Toast.LENGTH_SHORT);
        toast.show();
    }
}

Answer 1

您必须将OnValueChangeListener附加到NumberPicker。

你要做的就是：numberPicker.setOnValueChangedListener(this);