android - 从android中的 fragment 更改当前选项卡

Question

它有 5 个选项卡。每个选项卡都是一个 fragment 。我正在寻找的是以编程方式在选项卡之间切换。尝试了以下方法，但对我没有帮助。

=========================我的主要 Activity java================== =======

public class MainActivity extends AppCompatActivity {

private SectionsPageAdapter mSectionsPageAdapter;
private FirebaseAuth auth;
public ViewPager mViewPager;
public TabLayout tabLayout;
private final String TAG = "ListActivity";



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    auth = FirebaseAuth.getInstance();
    setContentView(R.layout.activity_main);


    this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
    mSectionsPageAdapter = new SectionsPageAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.container);
    setupViewPager(mViewPager);

    tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(mViewPager);


    tabLayout.getTabAt(0).setText("program");
    tabLayout.getTabAt(1).setText("security");
    tabLayout.getTabAt(2).setText("devices");
    tabLayout.getTabAt(3).setText("network");
    tabLayout.getTabAt(4).setText("sections");

    BottomNavigationView bottomNavigationView = (BottomNavigationView) findViewById(R.id.bottomNavView_Bar);
    BottomNavigationViewHelper.disableShiftMode(bottomNavigationView);
    Menu menu = bottomNavigationView.getMenu();
    MenuItem menuItem = menu.getItem(3);
    menuItem.setChecked(true);
    bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()){
                case R.id.ic_home:

                    break;

                case R.id.ic_message:
                    Intent intent1 = new Intent(MainActivity.this, ActivityOne.class);
                    startActivity(intent1);
                    break;

                case R.id.ic_add:
                    if (auth.getCurrentUser() != null) {
                        createNewListItem();
                    }else{
                        Toast.makeText(getApplicationContext(), "You have to Login to Add a new Service!", Toast.LENGTH_SHORT).show();
                    }

                    break;

                case R.id.ic_profile:
                    Intent intent3 = new Intent(MainActivity.this, ActivityThree.class);
                    startActivity(intent3);
                    break;

            }


            return false;
        }
    });



}

private void setupViewPager(ViewPager viewPager) {
    SectionsPageAdapter adapter = new SectionsPageAdapter(getSupportFragmentManager());
    adapter.addFragment(new Tab1Fragment());
    adapter.addFragment(new Tab2Fragment());
    adapter.addFragment(new Tab3Fragment());
    adapter.addFragment(new Tab4Fragment());
    adapter.addFragment(new Tab5Fragment());
    viewPager.setAdapter(adapter);
    viewPager.setCurrentItem(4);
}

==================================我的 fragment =========== ===============

public class RecyclerViewDataAdapter extends RecyclerView.Adapter<RecyclerViewDataAdapter.ItemRowHolder> {

private ArrayList<SectionDataModel> dataList;
private Context mContext;

public RecyclerViewDataAdapter(Context context, ArrayList<SectionDataModel> dataList) {
    this.dataList = dataList;
    this.mContext = context;
}

@Override
public ItemRowHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.list_item, null);
    ItemRowHolder mh = new ItemRowHolder(v);
    return mh;
}

@Override
public void onBindViewHolder(ItemRowHolder itemRowHolder, int i) {

    final String sectionName = dataList.get(i).getHeaderTitle();

    ArrayList singleSectionItems = dataList.get(i).getAllItemsInSection();

    itemRowHolder.itemTitle.setText(sectionName);

    SectionListDataAdapter itemListDataAdapter = new SectionListDataAdapter(mContext, singleSectionItems);

    itemRowHolder.recycler_view_list.setHasFixedSize(true);
    itemRowHolder.recycler_view_list.setLayoutManager(new LinearLayoutManager(mContext, LinearLayoutManager.HORIZONTAL, false));
    itemRowHolder.recycler_view_list.setAdapter(itemListDataAdapter);


     itemRowHolder.recycler_view_list.setNestedScrollingEnabled(false);


   /*  itemRowHolder.recycler_view_list.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            int action = event.getAction();
            switch (action) {
                case MotionEvent.ACTION_DOWN:
                    // Disallow ScrollView to intercept touch events.
                    v.getParent().requestDisallowInterceptTouchEvent(true);
                    break;
                case MotionEvent.ACTION_UP:
                    //Allow ScrollView to intercept touch events once again.
                    v.getParent().requestDisallowInterceptTouchEvent(false);
                    break;
            }
            // Handle RecyclerView touch events.
            v.onTouchEvent(event);
            return true;
        }
    });*/

    itemRowHolder.btnMore.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            TabLayout tabLayout = (TabLayout)v.findViewById(R.id.tabs);

            Toast.makeText(v.getContext(), "click event on more, "+sectionName , Toast.LENGTH_SHORT).show();
            if (sectionName=="sections"){
                tabLayout.getTabAt(5).select();
            }else if (sectionName=="network"){
                tabLayout.getTabAt(4).select();
            }else if(sectionName=="devices"){
                tabLayout.getTabAt(3).select();
            }else if(sectionName=="security"){
                tabLayout.getTabAt(2).select();
            }else {
                tabLayout.getTabAt(1).select();
            }


        }
    });

Answer 1

在 Activity 和 Fragment 之间进行通信的最简单方法是使用接口(interface)。这个想法基本上是在给定的 fragment A 中定义一个接口(interface)，并让 Activity 实现该接口(interface)。

一旦它实现了该接口(interface)，您就可以在它覆盖的方法中做任何您想做的事情。

有个好tutorial关于如何做这种事情。

希望对您有所帮助!