android - viewpager不同页面的不同菜单图标

Question

我是 Android 编程的新手，我有一个问题。在我的应用程序中，我有 ViewPager(带有一些 fragment )，在顶部我有带菜单图标的工具栏。当用户选择ViewPager的不同页面时，是否可以显示不同的图标。我知道 OnPageChangeListener 的 onPageSelected 方法在用户选择页面时有效，但我不明白如何更改图标。谁能给我一些例子或文章。谢谢!

Answer 1

这是可能的。如果你有 2 个页面，创建 2 个菜单资源文件 res > menu。例如

menu_one.xml

<menu 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"
    tools:context="mcrime.com.mcrime.MainActivity">



      <item
            android:id="@+id/send_icon"
            android:orderInCategory="100"
            android:icon="@drawable/ic_send_white_24dp"
            android:title="Send Report"
            app:showAsAction="always" />

    </menu>

菜单_2.xml

<menu 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"
    tools:context="mcrime.com.mcrime.MainActivity">

    <item
        android:id="@+id/make_a_call"
        android:orderInCategory="100"
        android:icon="@drawable/ic_call_white_24dp"
        android:title="Make Call"
        app:showAsAction="always" />

</menu>

然后在您的 MainActivity 上:

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

        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

 private void setUpVariables(){

        ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
        SlidingTabLayout slidingTabLayout = (SlidingTabLayout) findViewById(R.id.tab_layout);

        viewPager.setAdapter(new ViewPagerAdapter(getSupportFragmentManager()));
        slidingTabLayout.setCustomTabView(R.layout.tab_view, R.id.tab_text_view);
        slidingTabLayout.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {
            @Override
            public int getIndicatorColor(int position) {
                return getResources().getColor(R.color.colorAccent) ;
            }
        });

        slidingTabLayout.setDistributeEvenly(true);
        slidingTabLayout.setViewPager(viewPager);

        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                if(position == 0){
                    MCrime.this.setTitle("Your custom title");
                    toolbar.getMenu().clear();
                    toolbar.inflateMenu(R.menu.menu_one);
                } else if(position == 1){
                    MCrime.this.setTitle("Your custom title");
                    toolbar.getMenu().clear();
                    toolbar.inflateMenu(R.menu.menu_2);
                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

    }

您需要创建寻呼机适配器

 public class ViewPagerAdapter extends FragmentStatePagerAdapter {

        String [] titles = {"Title One", "Title Two", };

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

        @Override
        public Fragment getItem(int position) {
            Fragment fragment;
            if(position == 0){
                fragment = new FragmentOne();
                return fragment;
            }

            if(position == 1){
                fragment = new FragmentTwo();
                return fragment;
            }


            return null;
        }

        @Override
        public int getCount() {
            return 2;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return titles[position];
        }
    }