Android 导航抽屉活动、调用片段、空对象引用

我哪里出错了？我试图在Communicate_fragment中设置editText，并将其传递给receive_fragment，并在textView中显示它

如果我不使用导航抽屉活动，这不会是一个问题，因为我可以在MainActivity中绘制片段，这是我现在无法做到的，但我正在尝试学习如何以这种方式实现它

请给我指出正确的方向，因为我是初学者，正在努力学习手工艺

AndroidManager说：

Attempt to invoke virtual method 'void fragmentdrawer.recieve_fragment.setText(java.lang.String)' on a null object reference

但我不明白为什么

主要内容：

通信\u碎片类：

 package fragmentdrawer;

    import android.app.Activity;
    import android.os.Bundle;
    import android.support.annotation.Nullable;
    import android.app.Fragment;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.Button;
    import android.widget.EditText;

    import com.example.name.fragmentdrawer.R;


    public class communicate_fragment extends Fragment{

        private static EditText topTextInput;
        private static Button button;


        TopSectionListener activityCommander;

        public interface TopSectionListener{
            public void createMeme(String text);

        }

        @Override
        public void onAttach(Activity activity) {
            super.onAttach(activity);
            try {
                activityCommander = (TopSectionListener) activity;
            }catch (ClassCastException e) {
                throw  new ClassCastException(activity.toString());
            }
        }




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

            topTextInput = (EditText) rootView.findViewById(R.id.message);
            final Button button = (Button) rootView.findViewById(R.id.buttonSend);

            button.setOnClickListener(
                    new View.OnClickListener(){

                        public void onClick(View v){
                            buttonClicked(v);
                        }
                    }



            );



            return rootView;
        }

        public void buttonClicked(View view) {

            activityCommander.createMeme(topTextInput.getText().toString());



        }
    }

接收类帧

package fragmentdrawer;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import com.example.name.fragmentdrawer.R;

public class recieve_fragment extends Fragment{
    private static TextView textView;



    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_recieve, container, false);
        textView = (TextView) rootView.findViewById(R.id.displayMsg);
        return rootView;
    }

    public void setText(String text){
        textView.setText(text);
    }
}

receive_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent" android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Medium Text"
        android:id="@+id/displayMsg"
        android:layout_gravity="center" />


</FrameLayout>

您可以发布receive\u fragment类的xml文件吗？可能textview的id不正确，因此findViewById（）无法找到它，从而导致空值。@NarayanAcharya我现在已经添加了它，谢谢！可以现在能用了吗？不，同样的问题@NarayanAcharya

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent" android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Medium Text"
        android:id="@+id/displayMsg"
        android:layout_gravity="center" />


</FrameLayout>