Java 我的应用程序跳过AsyncTask.execute（）并崩溃

这是我的onCreate方法，问题是应用程序显示toast“Finish！”但它不执行

li.execute（电子邮件、密码）和它崩溃。就这样
我希望应用程序能够执行
li.execute（电子邮件、密码）第一个

PS:loginBackgroundWorker是一个扩展了
AsyncTask
的类，它有
onPreExecute（）
和
doInBackground（）
和
onPostExecute（）
方法。
应用程序没有显示任何错误或警告，但在模拟器中崩溃

代码如下：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    li = new loginBackgroundWorker(LoginActivity.this);
    //loginBackgroundWorker is a class that extends AsyncTask


    EditTextEmail =(EditText) findViewById(R.id.emailField);
    EditTextPassword =(EditText) findViewById(R.id.passwordField);
    loginButton = (CardView) findViewById(R.id.loginButton);

    loginButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Email = EditTextEmail.getText().toString().trim();
            Password = EditTextPassword.getText().toString().trim();

            li.execute(Email,Password);
            Toast.makeText(LoginActivity.this,"Finish !",Toast.LENGTH_LONG).show();
        }
    });

}

这里是AsyncTask类（我认为这些函数中的内容对您并不重要）

AsyncTask
的实例只能运行一次

如果要重用
AsyncTask
，必须初始化
loginBackgroundWorker
的新实例并运行它

将您的
loginBackgroundWorker
初始化移动到您的
OnClickListener。onClick
handle
显示您的
AsyncTask
和stacktrade dudeOK我将显示整个AsyncTask类以及您的异常stacktrace是什么？好的，我现在发布了我的stacktrace
无法执行任务：任务已经在运行。
您正在运行吗在别处启动任务，或者您可能正在多次单击该按钮。我这样做时，它会在多次单击后崩溃，这是我的Stacktrace每次单击时都会显示此错误E/Surface:getSlotFromBufferLocked:unknown buffer:0x7f811727d2e0，然后崩溃
-----------崩溃开始05-26 15:27:05.13720334-20334/com.example.zaariou.blacklist E/AndroidRuntime:致命异常：主进程：com.example.zaariou.blacklist，PID:20334 java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“java.lang.String java.lang.String.trim（）”
public class loginBackgroundWorker  extends AsyncTask<String,String,String> {
Context context;

public String email;
public String password;

public static final String login_url="http://192.168.0.104/login.php";


public loginBackgroundWorker(Context context) {
    this.context = context;
}


@Override
public void onPreExecute() {
    //Toast.makeText(context,"preExecute",Toast.LENGTH_LONG).show();
}

@Override
public String doInBackground(String... params) {

        try {
            email = params[0];
            password = params[1];
            URL url = new URL(login_url);
            HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);
            OutputStream outputStream = httpURLConnection.getOutputStream();
            BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
            String post_data = URLEncoder.encode("email","UTF-8")+"="+URLEncoder.encode(email,"UTF-8")+"&"
                    +URLEncoder.encode("password","UTF-8")+"="+URLEncoder.encode(password,"UTF-8");
            bufferedWriter.write(post_data);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();


            InputStream inputStream = httpURLConnection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
            String result="";
            String line="";
            while((line = bufferedReader.readLine())!= null) {
                result += line;
            }
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return result;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    return null;
}

@Override
public void onPostExecute(String result) {
    Toast.makeText(context,"Onpost",Toast.LENGTH_LONG).show();
    String r=result.trim();
    Boolean aBoolean = true;
    if (result.equals("1"))
    {
        Toast.makeText(context,"Bien Connecté",Toast.LENGTH_LONG).show();
        aBoolean =  false;
    }
    else if (result.equals(""))
        r = "Login ou mot de passe incorrect";

    if (aBoolean)
    {
        Toast.makeText(context,r,Toast.LENGTH_LONG).show();
    }


}
}

    --------- beginning of crash
    05-26 14:56:24.023 14756-14756/com.example.zaariou.blacklist E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.zaariou.blacklist, PID: 14756
java.lang.IllegalStateException: Cannot execute task: the task is already running.
    at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:593)
    at android.os.AsyncTask.execute(AsyncTask.java:551)
    at com.example.zaariou.blacklist.LoginActivity$1.onClick(LoginActivity.java:58)
    at android.view.View.performClick(View.java:5198)
    at android.view.View$PerformClick.run(View.java:21147)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)