findviewbyid-无法解决

Question

This is one of my fragments that I am using in a navigation drawer . I need to add a button that when pressed, changes to a text box into different text. I keep getting errors that the findviewbyid() int cannot be resolved and such. I could get this working on MainActivity/activity_main , but when I use one of the pages of the nav drawer(like ConnectFragment.java/fragment_connect.xml ), I get errors.

This is the code for just the ConnectFragment alone

import android.os.Bundle;
import android.os.PersistableBundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

public class ConnectFragment extends Fragment {
    public ConnectFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_connect, container, false);

        return rootView;
    }       
}

This is the code i want to implement

final Button ClassAButton = (Button)findViewById(R.id.ClassAButton);

ClassAButton.setOnClickListener(
    new Button.OnClickListener(){
        public void onClick(View view){
            TextView FeloniesText = (TextView)findViewById(R.id.FeloniesText);
            FeloniesText.setText("Button 1 Has been pressed!");
        }
    }
);

Code from the XML (relative layout tag here, formatting got messed up)

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="@color/backgroundColor">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="New Button"
        android:id="@+id/ClassAButton"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Large Text"
        android:id="@+id/FeloniesText"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="107dp" />
</RelativeLayout>

I also want to add multiple buttons to change the text view to different things, so I would be something like, Class A button prints out hi, Class B Button prints out yes, Class C Button prints out elephant, etc. Any help would be greatly appreciated. :D BTW API 15

Answer 1

Try this.

Change this line.

final Button ClassAButton = (Button)findViewById(R.id.ClassAButton);

To this.

final Button ClassAButton = (Button) rootView.findViewById(R.id.ClassAButton);

TextView FeloniesText = (TextView) rootView.findViewById(R.id.FeloniesText);

Edit : For text view try this.

ClassAButton.setOnClickListener(new View.OnClickListener(){
                public void onClick(View view){
                    FeloniesText.setText("Button 1 Has been pressed!");
                }
            }
    );

Replace this in your code.

Edit 2 :

Replace this full code with your code.

In reference link they have taken Activity and You have take fragment.

public class ConnectFragment extends Fragment {

final Button ClassAButton;
TextView FeloniesText;



public ConnectFragment() {
}

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

    View rootView = inflater.inflate(R.layout.fragment_connect, container, false);
    init(rootView);
    return rootView;

}


public void init(View view)
{
    ClassAButton = (Button) view.findViewById(R.id.ClassAButton);
    FeloniesText = (TextView) view.findViewById(R.id.FeloniesText);
    ClassAButton.setOnClickListener(new View.OnClickListener(){
                public void onClick(View view){
                    FeloniesText.setText("Button 1 Has been pressed!");
                }
            }
    );
}

Answer 2

findViewById is not part of Fragment . It's part of ViewGroup so instead of

(TextView)findViewById(R.id.FeloniesText);

you need to

(TextView)rootView.findViewById(R.id.FeloniesText);