Question

以下是我的学生适配器类，用于显示学生，它有一个切换按钮，可以将学生设置为最喜欢的学生。

当我将学生设置为最喜欢的（真实）时，应用程序崩溃了。

我的问题是如何更新realm文件中的数据，以便将喜爱的学生设置为true。

我的第二个问题是我可以在学生活动而不是学生适配器中这样做吗？我觉得这不对，但切换按钮位于视图中。

学生列表视图的学生适配器：

public class StudentAdapter  extends RealmBaseAdapter<Student> implements ListAdapter {

....
realm = Realm.getDefaultInstance();
....

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    final ViewHolder viewHolder;
    if (convertView == null) {
        convertView = inflater.inflate(R.layout.row_student, parent, false);
        viewHolder = new ViewHolder();

        viewHolder.studentID = (TextView) convertView.findViewById(R.id.rowStudentID);
        viewHolder.toggleBtn = (ToggleButton) convertView.findViewById(R.id.toggleStar);
        convertView.setTag(viewHolder);
    } else {
        viewHolder = (ViewHolder) convertView.getTag();
    }

    final Student item = realmResults.get(position);
   Boolean checkStar = item.getStudentFavourite();
    if (checkStar.equals(false)) {
        viewHolder.toggleBtn.setChecked(false);
    } else {
        viewHolder.toggleBtn.setChecked(true);
    }

    viewHolder.toggleBtn.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

            if (viewHolder.toggleBtn.isChecked()) {
            Student student = realm.where(Student.class).equalTo("StudentID", item.getStudentID()).findFirst();
                Log.d("toggle", String.valueOf(student));
                realm.beginTransaction();
               student.setStudentFavourite(true);
                realm.commitTransaction();
    ....
    return convertView;
    ....

学生对象

public class Student extends RealmObject{

@Required
private String StudentID;
private Boolean StudentFavourite;

public String getStudentID() {
    return StudentID;
}

public void setStudentID(String studentID) {
    StudentID = studentID;
}


public Boolean getStudentFavourite() {
    return StudentFavourite;
}

public void setStudentFavourite(Boolean studentFavourite) {
    StudentFavourite = studentFavourite;
}

}

EXCEPTION: main java.lang.NullPointerException at
    com.example.kent.schooldirectory.StudentAdapter$1.onCheckedChanged(StudentAdapter.java:85)
at android.widget.CompoundButton.setChecked(CompoundButton.java:126)
at android.widget.ToggleButton.setChecked(ToggleButton.java:73)
at com.example.kent.schooldirectory.StudentAdapter.getView(StudentAdapter.java:62)
at android.widget.AbsListView.obtainView(AbsListView.java:2251)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1244)

Answer 1

感谢您的回复。我设法找到答案。

如下：

viewHolder.toggleBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if (viewHolder.toggleBtn.isChecked()) {
                String test1 = item.getStudentID();
                Student favStudent = realm.where(Student.class).equalTo("StudentID", test1).findFirst();
                realm.beginTransaction();
                favStudent.setStudentFavourite(true);
                realm.commitTransaction();
                viewHolder.toggleBtn.setChecked(true);
                //Log.d("toggle", test1);

            } else {
                String test2 = item.getStudentID();
                Student notfavStudent = realm.where(Student.class).equalTo("StudentID", test2).findFirst();
                realm.beginTransaction();
                notfavStudent.setStudentFavourite(false);
                realm.commitTransaction();
                viewHolder.toggleBtn.setChecked(false);
                //Log.d("toggle", test2);


            }
        }

在列表视图中更新切换按钮的领域文件

1 个答案: