Question

所以我创建了一个webservice调用类，调用我的webservice，它扩展了AsyncTask：

public class WebServiceLoginCall extends AsyncTask{

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
    }

    protected void onPostExecute(Void result) {
        try {
             if(loginStatus){
                 System.out.println("onpost has been executed");
                 //Navigate to Home Screen
                 loginIntent = new Intent(getBaseContext(), HomeActivity.class);
                 startActivity(loginIntent);
                //prevents user to go back to the login screen
                finish();
                }else{
                    //Set Error message
                    Toast.makeText(getApplicationContext(), "Login Failed. Check your details.",  Toast.LENGTH_SHORT).show();
                }
        } catch (Exception e) {
            Toast.makeText(getApplicationContext(), "An error occured. Check your mobile connection.",  Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    protected Boolean doInBackground(Object... arg0) {
        System.out.println("doinbackground triggered");
        try {
            loginStatus = Webservice.invokeLoginWS(loginUser.get_userEmail(), loginUser.get_userPassword());
        } catch (Exception e) {
            System.out.println("an error occured with the webservice");
        }

        return loginStatus;
    }

}

当用户按下登录按钮时，我使用以下代码：

public void onClick(View v) {
    switch (v.getId()) {
    case R.id.btnLogin:
        email = (EditText) findViewById(R.id.txtEmail);
        loginUser = new User();
        loginUser.set_userEmail(email.getText().toString());
        loginUser.set_userPassword(password.getText().toString());

        //starts loging webservice
        WebServiceLoginCall task = new WebServiceLoginCall();
        //executes the login task
        task.execute();

    break;

当我检查时，在我的控制台中触发了doInBackground，但是没有onPostExecute。有什么我做错了吗？ doInBackground不会抛出任何异常。

Answer 1

进行以下两项更改

1.使用public class WebServiceLoginCall extends AsyncTask<Void, Void, Boolean > 而不是public class WebServiceLoginCall extends AsyncTask

2.使用

@Override
protected void onPostExecute(Void result) {
// your code
}

而不仅仅是

protected void onPostExecute(Void result) {
// your code
}

Refer Android- Async task

说明：

在你的情况下如果你在onPostExecute（）上放置@Override而不扩展通用的Asynctask，你将得到一个编译时错误。因此，您必须进行以上两项更改。

希望它可以帮到你。

Answer 2

因为你正在调用一个不同的方法，你的帖子执行将不会执行，如果你像你的代码一样定义

使用

@Override
protected void onPostExecute(boolean result) {

 }

Answer 3

因为你没有覆盖onPostExecute（）方法添加：@Override

像这样

@Override
protected void onPostExecute(Void result) {
        try {
             if(loginStatus){
                 System.out.println("onpost has been executed");
                 //Navigate to Home Screen
                 loginIntent = new Intent(getBaseContext(), HomeActivity.class);
                 startActivity(loginIntent);
                //prevents user to go back to the login screen
                finish();
                }else{
                    //Set Error message
                    Toast.makeText(getApplicationContext(), "Login Failed. Check your details.",  Toast.LENGTH_SHORT).show();
                }
        } catch (Exception e) {
            Toast.makeText(getApplicationContext(), "An error occured. Check your mobile connection.",  Toast.LENGTH_SHORT).show();
        }
    }

onPostExecute不会被触发

3 个答案: