Java 如何防止用户提交空文本？

代码显示为一个对话框片段，当按下add按钮时，该对话框片段有2个编辑文本，在EditText字段中输入的文本保存到数据库parse.com。在这种情况下，一切都很正常

我想做的是，当字段为空时，不允许用户将EditText添加到数据库中，我还想显示一条消息，说明其中一个字段为空或两个字段均为空

我该怎么做？

在这些行之后：

public class DialogAddSubject extends DialogFragment implements View.OnClickListener{


    Button add,cancel;
    EditText professorName;
    EditText subjectName;


    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.dialog_add_subject, null);
        add = (Button) view.findViewById(R.id.addsub);
        cancel = (Button) view.findViewById(R.id.cancel);
        add.setOnClickListener(this);
        cancel.setOnClickListener(this);


        subjectName = (EditText)view.findViewById(R.id.subjectName);
        professorName = (EditText)view.findViewById(R.id.professorName);


        getDialog().setTitle(R.string.add_sub);
        return view;

    }

    @Override
    public void onClick(View view) {

        if (view.getId()== R.id.addsub)



        {

            String subjName = subjectName.getText().toString();
            String profName = professorName.getText().toString();


            ParseObject userData = new ParseObject("UserData");
            userData.put("createdBy", ParseUser.getCurrentUser());
            userData.put("professor", profName);
            userData.put("subject", subjName);


            userData.saveInBackground();


            dismiss();
            Toast.makeText(getActivity(),"subject and professor successfully added",Toast.LENGTH_SHORT).show();
        }

        else


        {
            dismiss();

        }

    }
}

检查它们是否是空的，如果是空的，干杯并返回

String subjName = subjectName.getText().toString();
String profName = professorName.getText().toString();

请检查以下内容：

if (subjName.isEmpty() || profName.isEmpty()) {
    Toast.makeText(getActivity(), "Please input values", Toast.LENGTH_SHORT).show();
    return;
}

---

希望这有助于

在onclick的if条件下使用此选项

if (subjName.isEmpty() || profName.isEmpty()) {
    Toast.makeText(getActivity(), "Please provide all the values", Toast.LENGTH_SHORT).show();
}
else {
    ParseObject userData = new ParseObject("UserData");
    userData.put("createdBy", ParseUser.getCurrentUser());
    userData.put("professor", profName);
    userData.put("subject", subjName);
    userData.saveInBackground();
    dismiss();
    Toast.makeText(getActivity(),"subject and professor successfully added",Toast.LENGTH_SHORT).show();
}

---

您需要保留验证。你在谷歌上搜索过吗？

String subjName = subjectName.getText().toString();
                String profName = professorName.getText().toString();
    if(subjName.equals("")&& profName.equals(""))
    {
     Toast.makeText(getActivity(),"Please Enter empty fields",Toast.LENGTH_SHORT).show();
    }

    else
                ParseObject userData = new ParseObject("UserData");
                userData.put("createdBy", ParseUser.getCurrentUser());
                userData.put("professor", profName);
                userData.put("subject", subjName);
                userData.saveInBackground();
dismiss();
        Toast.makeText(getActivity(),"subject and professor successfully added",Toast.LENGTH_SHORT).show();