java - 使用选项卡和 fragment 处理导航项

Question

我创建了一个抽屉导航并添加了一个像这样的选项卡布局

activity_main

 <?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>

app_bar_main

    <?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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"
    tools:context=".MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />
        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabMode="fixed"
            app:tabGravity="fill"
            android:layout_gravity="bottom"
            app:tabSelectedTextColor="#fffaf0"/>
    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_main" />

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"  />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        app:srcCompat="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>

我得到的结果如下所示:

但是，我尝试将 fragment 添加到选项卡，以便每个导航项打开一个屏幕，其中有两个选项卡“第一学期”和“第二学期”，其内容保存在 fragment xml 中，但不起作用。

主要 Activity

    package com.lini.bdevelopers.geomaticshandbook;

//import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
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.support.v4.app.FragmentManager;
import android.view.Menu;
import android.view.MenuItem;
import java.util.ArrayList;
import java.util.List;


public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    ViewPager viewPager;
    TabLayout tabLayout;

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

        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();
            }
        });

        viewPager = findViewById(R.id.viewpager);
        //setupViewPager(viewPager);

        tabLayout = findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);

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

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

    // Create adapter for the view  pager
    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new FirstSemester(), "First Semester");
        adapter.addFragment(new SecondSemester(), "Second Semester");
        viewPager.setAdapter(adapter);
    }
    private void setupViewPager2(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new FirstSemester2(), "First Semester");
        adapter.addFragment(new SecondSemester2(), "Second Semester");
        viewPager.setAdapter(adapter);
    }
    private void setupViewPager3(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new FirstSemester3(), "First Semester");
        adapter.addFragment(new SecondSemester3(), "Second Semester");
        viewPager.setAdapter(adapter);
    }
    private void setupViewPager4(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new FirstSemeste4r(), "First Semester");
        adapter.addFragment(new SecondSemester4(), "Second Semester");
        viewPager.setAdapter(adapter);
    }
    private void setupViewPager5(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new FirstSemester5(), "First Semester");
        adapter.addFragment(new SecondSemester5(), "Second Semester");
        viewPager.setAdapter(adapter);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {

            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {

            return mFragmentList.size();
        }

        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {

            return mFragmentTitleList.get(position);
        }
    }

    @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.
        int id = item.getItemId();

        if (id == R.id.year1) {
            setupViewPager(viewPager);
        } else if (id == R.id.year2) {
            setupViewPager2(viewPager);
        } else if (id == R.id.year3) {
            setupViewPager3(viewPager);
        } else if (id == R.id.year4) {
            setupViewPager4(viewPager);
        } else if (id == R.id.year5) {
            setupViewPager5(viewPager);
        } else if (id == R.id.nav_share) {

        } else if (id == R.id.nav_send) {

        }

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

上面的代码将 FirstSemester() 和 SecondSemester() fragment 绑定(bind)到所有导航项。这可能不是正确的方法，所以我需要建议和帮助，谢谢。

其次如何将 AppBar 标题更改为所选导航项的标题？

Answer 1

Secondly How do I change the AppBar title to the title of the Navigation item selected?

在 MainActivity 类的 onNavigationItemSelected() 方法中..您可以执行以下操作:

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

    if (id == R.id.year1) {
        getSupportActionBar().setTitle("Year 1");
        setupViewPager(viewPager);
    } else if (id == R.id.year2) {
        getSupportActionBar().setTitle("Year 2");
        setupViewPager2(viewPager);
    } else if (id == R.id.year3) {
        getSupportActionBar().setTitle("Year 3");
        setupViewPager3(viewPager);
    } else if (id == R.id.year4) {
        getSupportActionBar().setTitle("Year 4");
        setupViewPager4(viewPager);
    } else if (id == R.id.year5) {
        getSupportActionBar().setTitle("Year 5");
        setupViewPager5(viewPager);
    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_send) {

    }

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

关于你的第一个问题，你正在为抽屉导航中单击的任何项目显示一个 View 页面(第一和第二学期)，因此你不应该期待一个看起来正常的代码。虽然方法比较粗暴，但是效率也不算太差。

我希望这会有所帮助......快乐编码!