Question

我正在尝试重用通过使用片段显示的View（.xml文件）。问题是，由于我重复使用该视图，因此我需要根据用户选择的课程名称重命名TextView's文本值。

public class StudentMultiplicationFragment extends Fragment{

    Button btnLesson1, btnLesson2, btnLesson3, btnLesson4, btnLesson5, btnLesson6;

    public StudentMultiplicationFragment() {
        // Required empty public constructor

    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.frag_studentmultiplication, container, false);
        btnLesson1 = view.findViewById(R.id.multiplication_lesson1);
        btnLesson2 = view.findViewById(R.id.multiplication_lesson2);
        btnLesson3 = view.findViewById(R.id.multiplication_lesson3);
        btnLesson4 = view.findViewById(R.id.multiplication_lesson4);
        btnLesson5 = view.findViewById(R.id.multiplication_lesson5);
        btnLesson6 = view.findViewById(R.id.multiplication_lesson6);

        btnLesson1.setOnClickListener(new goToLessonStartFragment(btnLesson1.getText().toString()));
        btnLesson2.setOnClickListener(new goToLessonStartFragment(btnLesson2.getText().toString()));
        btnLesson3.setOnClickListener(new goToLessonStartFragment(btnLesson3.getText().toString()));
        btnLesson4.setOnClickListener(new goToLessonStartFragment(btnLesson4.getText().toString()));
        btnLesson5.setOnClickListener(new goToLessonStartFragment(btnLesson5.getText().toString()));
        btnLesson6.setOnClickListener(new goToLessonStartFragment(btnLesson6.getText().toString()));
        return view;
    }

    private class goToLessonStartFragment implements View.OnClickListener{
        private String lessonName;

        public goToLessonStartFragment(String lessonName){
            this.lessonName = lessonName;
        }

        @Override
        public void onClick(View v) {
            LessonStartFragment lessonStartFragment = new LessonStartFragment();

            FragmentTransaction transaction = getFragmentManager().beginTransaction();
            transaction.replace(R.id.fragment_container, lessonStartFragment);
            transaction.addToBackStack(null);
            transaction.commit();
        }
    }
}

我试过

LessonStartFragment lessonStartFragment = new LessonStartFragment();
TextView tv =  lessonStartFragment.getView().findViewById(v.getId());
tv.setText(lessonName);

但它返回

java.lang.NullPointerException：尝试调用虚拟方法＆＃39; android.view.View android.view.View.findViewById（int）＆＃39;在空对象引用上

我认为我从v.getId()获得的ID与片段视图组件中的实际ID不匹配。

每个button（btnLesson1，btnLesson2，btnLesson3 ......等等......）的标题都设置在button＆＃39 ; s文本。我正在尝试将其文本设置为片段（LessonStartFragment）Textview。

我该怎么办呢？

我很感激任何帮助。

感谢。

Answer 1

尝试像这样强制按钮： -

 btnLesson1 = (Button)view.findViewById(R.id.multiplication_lesson1);
 btnLesson2 = (Button)view.findViewById(R.id.multiplication_lesson2);
 btnLesson3 = (Button) view.findViewById(R.id.multiplication_lesson3);
 btnLesson4 = (Button) view.findViewById(R.id.multiplication_lesson4);
 btnLesson5 = (Button)view.findViewById(R.id.multiplication_lesson5);
 btnLesson6 = (Button)view.findViewById(R.id.multiplication_lesson6);

获取Button的视图ID以更改片段视图组件的属性

1 个答案: