java - 如何解决此问题 : Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference

Question

我已经阅读了此处的另一篇文章，但似乎无法弄清楚为什么会出现此错误。错误在标题中，也在此处:Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference

我尝试添加 msg = (EditText)v.findViewById(R.id.msgTxt);但这仍然没有解决任何问题。

public class HelpFragment extends Fragment {
Button sendEmail;
EditText msg;


@Nullable

protected void process(View view) {

    }

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_help, null);
     sendEmail = (Button)v.findViewById(R.id.SendBtn);
      sendEmail.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v){
          msg = (EditText)v.findViewById(R.id.msgTxt);
           String message = msg.getText().toString();
            sendEmail(message);
        }

    });
        return v;
}
    protected void sendEmail(String message){
    String to= new String("em@sd.xo");
    String subject=("a message from app");
    Intent emailIntent = new Intent(Intent.ACTION_SEND);
    emailIntent.putExtra(Intent.EXTRA_EMAIL, to);
    emailIntent.putExtra(Intent.EXTRA_SUBJECT, subject);
    emailIntent.putExtra(Intent.EXTRA_TEXT, message);
    emailIntent.setType("message/rfc822");
    startActivity(Intent.createChooser(emailIntent, "Email"));
}

}

Answer 1

您引用了 onClick 的 View。您应该在 onClick() 方法之前实现 msg = (EditText)v.findViewById(R.id.msgTxt);

您应该使用 editText.getText().toString()，因为 editText.getText() 返回 Editable

---

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_help, null);
     sendEmail = (Button)v.findViewById(R.id.SendBtn);
     msg = (EditText)v.findViewById(R.id.msgTxt);

      sendEmail.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v){
           String message = msg.getText().toString();
            sendEmail(message);
        }

    });
        return v;
}