Question

我正在使用滑动视图制作登录注销模块我将类扩展为用于滑动视图的片段，然后我收到了此错误＆＃34;构造函数AlertDialog.Builder（Android）未定义＆＃34; 这种情况发生在我将类扩展到我使用活动之前工作的片段之后

我的整个代码

Android.java

    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentActivity;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    import android.app.Activity;
    import android.app.AlertDialog;
    import android.content.DialogInterface;
    import android.content.Intent;
    import android.os.Bundle;
    import android.view.View;
    import android.view.Window;
    import android.view.WindowManager;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    import android.widget.ImageButton;
    import android.widget.TextView;
    import android.widget.Toast;

    import com.learn2crack.library.DatabaseHandler;
    import com.learn2crack.tab.Android;


import java.util.HashMap;

public class Android extends Fragment {

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) 
    {


            View android = inflater.inflate(R.layout.android_frag, container, false);
            DatabaseHandler db = new DatabaseHandler(getActivity());

            HashMap<String,String> user = new HashMap<String, String>();
            user = db.getUserDetails();

            /**
             * Displays the registration details in Text view
             **/
            final ImageButton logoutbtn = (ImageButton)android.findViewById(R.id.logoutbtn);
            final TextView fname = (TextView)android.findViewById(R.id.fname);
            final TextView lname = (TextView)android.findViewById(R.id.lname);
            final TextView uname = (TextView)android.findViewById(R.id.uname);
            final TextView email = (TextView)android.findViewById(R.id.email);
            final TextView created_at = (TextView)android.findViewById(R.id.regat);
            fname.setText(user.get("fname"));
            lname.setText(user.get("lname"));
            uname.setText(user.get("uname"));
            email.setText(user.get("email"));
            created_at.setText(user.get("created_at"));


            logoutbtn.setOnClickListener(new OnClickListener(){
                @Override
                public void onClick(View v) {
                logout();
                }
                });
            return android;}

                public void logout(){
                AlertDialog.Builder alertDialog = new AlertDialog.Builder(Android.this);

                alertDialog.setTitle("Logout"); // Sets title for your alertbox

                alertDialog.setMessage("Are you sure you want to Logout ?"); // Message to be displayed on alertbox



                /* When positive (yes/ok) is clicked */
                alertDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog,int which) {
                    Intent login = new Intent(getActivity(), Login.class);
                    login.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(login);
                    // Closing dashboard screen
                    getActivity().finish();

                }
                });

                /* When negative (No/cancel) button is clicked*/
                alertDialog.setNegativeButton("No", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                dialog.cancel();
                }
                });
                alertDialog.show();
                }
}

Answer 1

如果您的父类（Function）有一个构造函数，您的子类也需要有一个，否则请使用Android.this.getActivity());。

Answer 2

Fragments不要从Context延伸，您需要提供Context参数。因此，请使用Android.this。

，而不是Android.this.getActivity()

构造函数是未定义的错误？

2 个答案: