Java 导航抽屉活动，通过碎片发送

我已经创建了一个导航抽屉活动。 我想将信息（通过EditText和按钮）发送到我的receive_片段，信息应显示在TextView中。 当我试图在我的主活动中实现一个接口并在我的各个片段中添加“sEntEdt”和“StEtTeX”方法时，我得到了一个错误消息：“NULL没有被定义”，所以我不得不考虑另一种用法，但是我完全被卡住了。我怎样才能从我的通信类发送消息，最终进入我的Receive\u fragmentclass

沟通：

public class communicate_fragment extends Fragment{   

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

        return rootView;
    }    
    }

发送片段

public class recieve_fragment extends Fragment{    

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

我曾尝试在我的主_活动中添加一个接口，用于处理来自communicate_片段的请求并将其发送回receive_片段，但我收到了错误消息“cannot instansiate”

主要活动

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        android.app.FragmentManager fm = getFragmentManager();
        fm.beginTransaction().replace(R.id.content_frame, new mainfragment()).commit();
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.

        android.app.FragmentManager fm = getFragmentManager();

        int id = item.getItemId();

        if (id == R.id.about_me) {
            fm.beginTransaction().replace(R.id.content_frame, new about_me_fragment()).commit();

        } else if (id == R.id.another_fragment) {
            fm.beginTransaction().replace(R.id.content_frame, new another_fragment()).commit();    

        } else if (id == R.id.send) {
            fm.beginTransaction().replace(R.id.content_frame, new communicate_fragment()).commit();

        }
        else if (id == R.id.recieve) {
            fm.beginTransaction().replace(R.id.content_frame, new recieve_fragment()).commit();
        }

            DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }    
}

---

首先创建侦听器接口：

public interface YourCustomListener {
    void onItemClick(int position, int ID);
}

现在将此添加到您的第一个片段：

YourCustomListener mListener;

以及您的片段onclick方法：

mListener.onItemClick(position,"YOUR ID");

添加以下内容：

@Override
    public void onAttach(Context con) {
        super.onAttach(con);
        try {
            mListener= (YourCustomListener ) con;
        } catch (ClassCastException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onDetach() {
        mListener=null;
        super.onDetach();
    }

在活动类中实现接口。 在衍生方法中：

@Override
    public void onItemClick(int position,int ID) {
        fragment2 =new SecondFragment();
        Bundle arg= new Bundle();
        arg.putInt("ID",ID);
        arg.putString("title","ANY TITLE");
        fragment2.setArguments(arg);

        if (fragment2 != null) {
            FragmentManager fragmentManager = getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.setCustomAnimations(R.anim.slide_left_enter,R.anim.slide_left_exit,R.anim.slide_left_enter,R.anim.slide_left_exit);
            fragmentTransaction.replace(R.id.container_body, fragment2,"PROF");
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();
            getSupportActionBar().setLogo(null);
        }
    }

现在在第二个片段中，在on Create方法中使用以下内容：

Bundle pb=getArguments();
        h=pb.getInt("ID");
        title=pb.getString("title");

---

现在有了int h的值和字符串Title。使用此值在文本视图中显示。

首先创建侦听器界面：

public interface YourCustomListener {
    void onItemClick(int position, int ID);
}

现在将此添加到您的第一个片段：

YourCustomListener mListener;

以及您的片段onclick方法：

mListener.onItemClick(position,"YOUR ID");

添加以下内容：

@Override
    public void onAttach(Context con) {
        super.onAttach(con);
        try {
            mListener= (YourCustomListener ) con;
        } catch (ClassCastException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onDetach() {
        mListener=null;
        super.onDetach();
    }

在活动类中实现接口。 在衍生方法中：

@Override
    public void onItemClick(int position,int ID) {
        fragment2 =new SecondFragment();
        Bundle arg= new Bundle();
        arg.putInt("ID",ID);
        arg.putString("title","ANY TITLE");
        fragment2.setArguments(arg);

        if (fragment2 != null) {
            FragmentManager fragmentManager = getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.setCustomAnimations(R.anim.slide_left_enter,R.anim.slide_left_exit,R.anim.slide_left_enter,R.anim.slide_left_exit);
            fragmentTransaction.replace(R.id.container_body, fragment2,"PROF");
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();
            getSupportActionBar().setLogo(null);
        }
    }

现在在第二个片段中，在on Create方法中使用以下内容：

Bundle pb=getArguments();
        h=pb.getInt("ID");
        title=pb.getString("title");

现在有了int h的值和字符串Title。使用此值在文本视图中显示。

，这应该对您有所帮助。。这应该对您有所帮助。