单击按钮时更改片段

Question

单击按钮时如何更改片段？我正在使用 android studio 1.5 并使用新的导航抽屉。

这是我的 MainActivity.java

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;

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, "bryanposvoc1339.garcia@gmail.com", 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);
    }

    @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) {
        int id = item.getItemId();
        Fragment fragment;

        if (id == R.id.nav_cough) {
             fragment = new first();
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.mainFrame, fragment);
            ft.commit();
        }
        else if (id == R.id.nav_colds) {
              fragment = new second();
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.mainFrame, fragment);
            ft.commit();
        }
        else if (id == R.id.nav_fever) {
            fragment = new third();
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.mainFrame, fragment);
            ft.commit();
        }
        else if (id == R.id.nav_vegetables) {
            fragment = new fourth();
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.mainFrame, fragment);
            ft.commit();
        } else if (id == R.id.nav_fruits) {
            fragment = new fifth();
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.mainFrame, fragment);
            ft.commit();
        } else if (id == R.id.nav_about) {
            fragment = new sixth();
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.mainFrame, fragment);
            ft.commit();
        }
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }
}

这是我的 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <include
        layout="@layout/app_bar_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:menu="@menu/activity_main_drawer" />

</android.support.v4.widget.DrawerLayout>

content_main.xml 这是我的框架布局所在的位置

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="appnaturemedicine.com.example.posvoc.naturesmedicine.MainActivity"
    tools:showIn="@layout/app_bar_main"
    android:background="@drawable/background">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent" android:id="@+id/mainFrame">
    </FrameLayout>        
</RelativeLayout>

我可以转到我想要的片段，问题是我如何使片段中的按钮在点击时更改当前片段

这是我单击导航抽屉中的一个菜单时的第一个片段

fragment_first.xml

<RelativeLayout 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"
    tools:context="appnaturemedicine.com.example.posvoc.naturesmedicine.first">


    <ImageView
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:id="@+id/imageView2"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:background="@mipmap/ic_launcher_cough" />

    <Button
        android:layout_width="80dp"
        android:layout_height="30dp"
        android:id="@+id/button"
        android:layout_alignBottom="@+id/textView3"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:onClick="onButtonClicked"
        />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Lagundi (Vitex negundo)"
        android:id="@+id/textView3"
        android:textColor="#ff4081"
        android:layout_below="@+id/imageView3"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Honey"
        android:id="@+id/textView4"
        android:textColor="#ff4081"
        android:layout_alignBottom="@+id/button3"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="80dp"
        android:layout_height="30dp"
        android:id="@+id/button3"
        android:layout_below="@+id/button"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Probiotics"
        android:id="@+id/textView5"
        android:layout_alignBottom="@+id/button4"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_toLeftOf="@+id/button4"
        android:textColor="#ff4081"
        android:layout_toStartOf="@+id/button4" />

    <Button
        android:layout_width="80dp"
        android:layout_height="30dp"
        android:id="@+id/button4"
        android:layout_below="@+id/textView4"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />

    <Button
        android:layout_width="80dp"
        android:layout_height="30dp"
        android:id="@+id/button5"
        android:layout_below="@+id/button4"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />

    <Button
        android:layout_width="80dp"
        android:layout_height="30dp"
        android:id="@+id/button6"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_below="@+id/button5" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Bromelain"
        android:id="@+id/textView6"
        android:textColor="#ff4081"
        android:layout_alignBaseline="@+id/button5"
        android:layout_alignBottom="@+id/button5"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Peppermint"
        android:id="@+id/textView7"
        android:textColor="#ff4081"
        android:layout_alignBaseline="@+id/button6"
        android:layout_alignBottom="@+id/button6"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <ImageView
        android:layout_width="250dp"
        android:layout_height="110dp"
        android:id="@+id/imageView3"
        android:background="@drawable/ben"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

first.java

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


/**
 * A simple {@link Fragment} subclass.
 */
public class first extends Fragment {


    public first() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_first, container, false);
    }

}

你能不能让它像当你点击 btn1 时它转到 fragmentOne 而当点击 btn2 它转到 fragmentTwo 时一样 if-else 语句？

我在这里放什么？

Answer 1

您可以为此使用 OnfragmentInteractionListener。这是您的活动应该实现的接口。您可以从片段中调用方法，就像从活动中调用方法一样。

在以下示例中，first 片段有一个按钮，单击该按钮时会调用方法 changeFragment(2)，类似地，second 片段会调用方法 changeFragment(1)。此方法在主活动中实现，并通过 if .. else 确定要替换的片段。

OnFragmentInteractionListener.java

public interface OnFragmentInteractionListener {
        public void changeFragment(int id);
}

片段A：

public class first extends Fragment {

    private OnFragmentInteractionListener mListener;

    public first() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_first, container, false);
        Button btn = (Button) view.findViewById(R.id.btn);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mListener.changeFragment(2);
            }
        });
        return view;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mListener = (OnFragmentInteractionListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                + " must implement OnFragmentInteractionListener");
        }
    }

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

    }

}

片段B：

public class first extends Fragment {

    private OnFragmentInteractionListener mListener;

    public first() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_first, container, false);
        Button btn = (Button) view.findViewById(R.id.btn);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mListener.changeFragment(1);
            }
        });
        return view;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mListener = (OnFragmentInteractionListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                + " must implement OnFragmentInteractionListener");
        }
    }

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

    }

}

主活动：

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener, OnFragmentInteractionListener {

    //Rest of the code

    @Override
    public void changeFragment(int id){
        if (id == 1) {
            fragment = new first();
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.mainFrame, fragment);
            ft.commit();
        }
        else if (id == 2) {
            fragment = new second();
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.mainFrame, fragment);
            ft.commit();
        }
    }
}

希望对你有帮助！！