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Android 将数据从活动传递到已附加片段的方法

android android-fragments

Android 将数据从活动传递到已附加片段的方法,android,android-fragments,android-activity,android-bundle,Android,Android Fragments,Android Activity,Android Bundle,我一直在研究这个问题，尽管我找到了一些信息，但似乎有些细节我还没有掌握。我想将信息从一个活动传递到一个已经附加的片段。这是当前代码： SearchActivity.java public class SearchActivity extends AppCompatActivity { private static final int FRAG_USERS = 0; private static final int FRAG_MESSAGES = 1; private i

我一直在研究这个问题，尽管我找到了一些信息，但似乎有些细节我还没有掌握。我想将信息从一个活动传递到一个已经附加的片段。这是当前代码：

SearchActivity.java

public class SearchActivity extends AppCompatActivity {

    private static final int FRAG_USERS = 0;
    private static final int FRAG_MESSAGES = 1;
    private int currentFrag = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);
        setupActionBar();
        setupViewPager();
    }

    private void setupActionBar() {
        ActionBar actionBar = this.getSupportActionBar();
        actionBar.setTitle("");
        actionBar.setDisplayHomeAsUpEnabled(true);
    }

    private void setupViewPager() {
        ViewPager2 searchVP2 = findViewById(R.id.searchVP2);
        searchVP2.setAdapter(new SearchPagerAdapter(this));

        TabLayout searchTL = findViewById(R.id.searchTL);
        TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(searchTL, searchVP2, (tab, position) -> {
            switch (position) {
                case 0: {
                    tab.setText(R.string.users);
                    break;
                } case 1: {
                    tab.setText(R.string.messages);
                    break;
                }
            }
        });
        tabLayoutMediator.attach();

        searchTL.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                currentFrag = searchTL.getSelectedTabPosition();
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) { }
            @Override
            public void onTabReselected(TabLayout.Tab tab) { }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_searchable, menu);
        SearchView searchView = (SearchView) menu.findItem(R.id.searchIT).getActionView();
        searchView.setMaxWidth(Integer.MAX_VALUE);
        searchView.setIconified(false);
        searchView.setFocusable(true);
        searchView.requestFocusFromTouch();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String query) {
                if (!TextUtils.isEmpty(query)) {
                    if (currentFrag == FRAG_USERS) {
                        Bundle bundle = new Bundle();
                        bundle.putString(Constants.BUNDLE_SEARCH, query);
                        new SearchUserFragment().setArguments(bundle);
                        //SearchUserFragment.newInstance(query);
                    } else {
                        SearchMessageFragment.newInstance(query);
                    }
                }
                return true;
            }
        });
        return true;
    }

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return true;
    }
}

public class SearchPagerAdapter extends FragmentStateAdapter {

    public SearchPagerAdapter(@NonNull FragmentActivity fragmentActivity) {
        super(fragmentActivity);
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        if (position == 0) {
            return new SearchUserFragment();
        } else {
            return new SearchMessageFragment();
        }
    }

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

            @Override
            public boolean onQueryTextChange(String query) {
                if (!TextUtils.isEmpty(query)) {
                    if (currentFrag == FRAG_USERS) {
                        Bundle bundle = new Bundle();
                        bundle.putString(Constants.BUNDLE_SEARCH, query);
                        new SearchUserFragment().setArguments(bundle);
                    } else {
                        SearchMessageFragment.newInstance(query);
                    }
                }
                return true;
            }

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_search_message, container, false);
        notFoundTV = view.findViewById(R.id.notFoundTV);
        searchTipCV = view.findViewById(R.id.searchTipCV);
        refreshRV(view);
        Bundle bundle = this.getArguments();
        if (bundle != null) {
            searchUser(bundle.getString(BUNDLE_SEARCH));
        }
        return view;
    }

public class SearchActivity extends AppCompatActivity {

    private ViewPager2 searchVP2;
    private String globalQuery;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);
        setupActionBar();
        setupViewPager();
    }

    private void setupActionBar() {
        ActionBar actionBar = this.getSupportActionBar();
        actionBar.setTitle("");
        actionBar.setDisplayHomeAsUpEnabled(true);
    }

    private void setupViewPager() {
        searchVP2 = findViewById(R.id.searchVP2);
        searchVP2.setAdapter(new SearchPagerAdapter(this));

        TabLayout searchTL = findViewById(R.id.searchTL);
        TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(searchTL, searchVP2, (tab, position) -> {
            switch (position) {
                case 0: {
                    tab.setText(R.string.users);
                    break;
                }
                case 1: {
                    tab.setText(R.string.messages);
                    break;
                }
            }
        });
        tabLayoutMediator.attach();

        searchTL.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                searchInCurrentFrag(globalQuery, tab.getPosition());
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) { }
            @Override
            public void onTabReselected(TabLayout.Tab tab) { }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_searchable, menu);
        SearchView searchView = (SearchView) menu.findItem(R.id.searchIT).getActionView();
        searchView.setMaxWidth(Integer.MAX_VALUE);
        searchView.setIconified(false);
        searchView.setFocusable(true);
        searchView.requestFocusFromTouch();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String query) {
                globalQuery = query;
                if (!TextUtils.isEmpty(query)) {
                    searchInCurrentFrag(query, searchVP2.getCurrentItem());
                }
                return true;
            }
        });
        return true;
    }

    private void searchInCurrentFrag(String query, int position) {
        if (query != null) {
            Fragment currentFragment = getSupportFragmentManager().findFragmentByTag("f" + position);
            if (currentFragment instanceof SearchUserFragment) {
                ((SearchUserFragment) currentFragment).searchUser(query);
            } else {
                ((SearchMessageFragment) currentFragment).searchMessage(query);
            }
        }
    }

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return true;
    }
}
SearchUserFragment.java（消息片段在这方面是相同的）

我不明白为什么我在研究过程中发现的一些newInstance（）方法会返回片段本身。我已经在SearchUserFragment中尝试了以下方法：

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null && getArguments().containsKey(BUNDLE_SEARCH)) {
            searchUser(savedInstanceState.getString(BUNDLE_SEARCH));
        }
    }

    public static SearchUserFragment newInstance(String query) {
        SearchUserFragment searchUserFragment = new SearchUserFragment();

        Bundle args = new Bundle();
        args.putString(BUNDLE_SEARCH, query);
        searchUserFragment.setArguments(args);

        return searchUserFragment;
    }
但它没有成功，就像newInstance（）没有实例化片段的另一个实例一样。应用程序没有崩溃，但当我在SearchView中键入内容时不会发生任何事情

我也尝试过这样做： SearchActivity.java

public class SearchActivity extends AppCompatActivity {

    private static final int FRAG_USERS = 0;
    private static final int FRAG_MESSAGES = 1;
    private int currentFrag = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);
        setupActionBar();
        setupViewPager();
    }

    private void setupActionBar() {
        ActionBar actionBar = this.getSupportActionBar();
        actionBar.setTitle("");
        actionBar.setDisplayHomeAsUpEnabled(true);
    }

    private void setupViewPager() {
        ViewPager2 searchVP2 = findViewById(R.id.searchVP2);
        searchVP2.setAdapter(new SearchPagerAdapter(this));

        TabLayout searchTL = findViewById(R.id.searchTL);
        TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(searchTL, searchVP2, (tab, position) -> {
            switch (position) {
                case 0: {
                    tab.setText(R.string.users);
                    break;
                } case 1: {
                    tab.setText(R.string.messages);
                    break;
                }
            }
        });
        tabLayoutMediator.attach();

        searchTL.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                currentFrag = searchTL.getSelectedTabPosition();
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) { }
            @Override
            public void onTabReselected(TabLayout.Tab tab) { }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_searchable, menu);
        SearchView searchView = (SearchView) menu.findItem(R.id.searchIT).getActionView();
        searchView.setMaxWidth(Integer.MAX_VALUE);
        searchView.setIconified(false);
        searchView.setFocusable(true);
        searchView.requestFocusFromTouch();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String query) {
                if (!TextUtils.isEmpty(query)) {
                    if (currentFrag == FRAG_USERS) {
                        Bundle bundle = new Bundle();
                        bundle.putString(Constants.BUNDLE_SEARCH, query);
                        new SearchUserFragment().setArguments(bundle);
                        //SearchUserFragment.newInstance(query);
                    } else {
                        SearchMessageFragment.newInstance(query);
                    }
                }
                return true;
            }
        });
        return true;
    }

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return true;
    }
}

public class SearchPagerAdapter extends FragmentStateAdapter {

    public SearchPagerAdapter(@NonNull FragmentActivity fragmentActivity) {
        super(fragmentActivity);
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        if (position == 0) {
            return new SearchUserFragment();
        } else {
            return new SearchMessageFragment();
        }
    }

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

            @Override
            public boolean onQueryTextChange(String query) {
                if (!TextUtils.isEmpty(query)) {
                    if (currentFrag == FRAG_USERS) {
                        Bundle bundle = new Bundle();
                        bundle.putString(Constants.BUNDLE_SEARCH, query);
                        new SearchUserFragment().setArguments(bundle);
                    } else {
                        SearchMessageFragment.newInstance(query);
                    }
                }
                return true;
            }

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_search_message, container, false);
        notFoundTV = view.findViewById(R.id.notFoundTV);
        searchTipCV = view.findViewById(R.id.searchTipCV);
        refreshRV(view);
        Bundle bundle = this.getArguments();
        if (bundle != null) {
            searchUser(bundle.getString(BUNDLE_SEARCH));
        }
        return view;
    }

public class SearchActivity extends AppCompatActivity {

    private ViewPager2 searchVP2;
    private String globalQuery;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);
        setupActionBar();
        setupViewPager();
    }

    private void setupActionBar() {
        ActionBar actionBar = this.getSupportActionBar();
        actionBar.setTitle("");
        actionBar.setDisplayHomeAsUpEnabled(true);
    }

    private void setupViewPager() {
        searchVP2 = findViewById(R.id.searchVP2);
        searchVP2.setAdapter(new SearchPagerAdapter(this));

        TabLayout searchTL = findViewById(R.id.searchTL);
        TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(searchTL, searchVP2, (tab, position) -> {
            switch (position) {
                case 0: {
                    tab.setText(R.string.users);
                    break;
                }
                case 1: {
                    tab.setText(R.string.messages);
                    break;
                }
            }
        });
        tabLayoutMediator.attach();

        searchTL.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                searchInCurrentFrag(globalQuery, tab.getPosition());
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) { }
            @Override
            public void onTabReselected(TabLayout.Tab tab) { }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_searchable, menu);
        SearchView searchView = (SearchView) menu.findItem(R.id.searchIT).getActionView();
        searchView.setMaxWidth(Integer.MAX_VALUE);
        searchView.setIconified(false);
        searchView.setFocusable(true);
        searchView.requestFocusFromTouch();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String query) {
                globalQuery = query;
                if (!TextUtils.isEmpty(query)) {
                    searchInCurrentFrag(query, searchVP2.getCurrentItem());
                }
                return true;
            }
        });
        return true;
    }

    private void searchInCurrentFrag(String query, int position) {
        if (query != null) {
            Fragment currentFragment = getSupportFragmentManager().findFragmentByTag("f" + position);
            if (currentFragment instanceof SearchUserFragment) {
                ((SearchUserFragment) currentFragment).searchUser(query);
            } else {
                ((SearchMessageFragment) currentFragment).searchMessage(query);
            }
        }
    }

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return true;
    }
}
SearchUserFragment.java

public class SearchActivity extends AppCompatActivity {

    private static final int FRAG_USERS = 0;
    private static final int FRAG_MESSAGES = 1;
    private int currentFrag = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);
        setupActionBar();
        setupViewPager();
    }

    private void setupActionBar() {
        ActionBar actionBar = this.getSupportActionBar();
        actionBar.setTitle("");
        actionBar.setDisplayHomeAsUpEnabled(true);
    }

    private void setupViewPager() {
        ViewPager2 searchVP2 = findViewById(R.id.searchVP2);
        searchVP2.setAdapter(new SearchPagerAdapter(this));

        TabLayout searchTL = findViewById(R.id.searchTL);
        TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(searchTL, searchVP2, (tab, position) -> {
            switch (position) {
                case 0: {
                    tab.setText(R.string.users);
                    break;
                } case 1: {
                    tab.setText(R.string.messages);
                    break;
                }
            }
        });
        tabLayoutMediator.attach();

        searchTL.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                currentFrag = searchTL.getSelectedTabPosition();
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) { }
            @Override
            public void onTabReselected(TabLayout.Tab tab) { }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_searchable, menu);
        SearchView searchView = (SearchView) menu.findItem(R.id.searchIT).getActionView();
        searchView.setMaxWidth(Integer.MAX_VALUE);
        searchView.setIconified(false);
        searchView.setFocusable(true);
        searchView.requestFocusFromTouch();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String query) {
                if (!TextUtils.isEmpty(query)) {
                    if (currentFrag == FRAG_USERS) {
                        Bundle bundle = new Bundle();
                        bundle.putString(Constants.BUNDLE_SEARCH, query);
                        new SearchUserFragment().setArguments(bundle);
                        //SearchUserFragment.newInstance(query);
                    } else {
                        SearchMessageFragment.newInstance(query);
                    }
                }
                return true;
            }
        });
        return true;
    }

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return true;
    }
}

public class SearchPagerAdapter extends FragmentStateAdapter {

    public SearchPagerAdapter(@NonNull FragmentActivity fragmentActivity) {
        super(fragmentActivity);
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        if (position == 0) {
            return new SearchUserFragment();
        } else {
            return new SearchMessageFragment();
        }
    }

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

            @Override
            public boolean onQueryTextChange(String query) {
                if (!TextUtils.isEmpty(query)) {
                    if (currentFrag == FRAG_USERS) {
                        Bundle bundle = new Bundle();
                        bundle.putString(Constants.BUNDLE_SEARCH, query);
                        new SearchUserFragment().setArguments(bundle);
                    } else {
                        SearchMessageFragment.newInstance(query);
                    }
                }
                return true;
            }

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_search_message, container, false);
        notFoundTV = view.findViewById(R.id.notFoundTV);
        searchTipCV = view.findViewById(R.id.searchTipCV);
        refreshRV(view);
        Bundle bundle = this.getArguments();
        if (bundle != null) {
            searchUser(bundle.getString(BUNDLE_SEARCH));
        }
        return view;
    }

public class SearchActivity extends AppCompatActivity {

    private ViewPager2 searchVP2;
    private String globalQuery;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);
        setupActionBar();
        setupViewPager();
    }

    private void setupActionBar() {
        ActionBar actionBar = this.getSupportActionBar();
        actionBar.setTitle("");
        actionBar.setDisplayHomeAsUpEnabled(true);
    }

    private void setupViewPager() {
        searchVP2 = findViewById(R.id.searchVP2);
        searchVP2.setAdapter(new SearchPagerAdapter(this));

        TabLayout searchTL = findViewById(R.id.searchTL);
        TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(searchTL, searchVP2, (tab, position) -> {
            switch (position) {
                case 0: {
                    tab.setText(R.string.users);
                    break;
                }
                case 1: {
                    tab.setText(R.string.messages);
                    break;
                }
            }
        });
        tabLayoutMediator.attach();

        searchTL.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                searchInCurrentFrag(globalQuery, tab.getPosition());
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) { }
            @Override
            public void onTabReselected(TabLayout.Tab tab) { }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_searchable, menu);
        SearchView searchView = (SearchView) menu.findItem(R.id.searchIT).getActionView();
        searchView.setMaxWidth(Integer.MAX_VALUE);
        searchView.setIconified(false);
        searchView.setFocusable(true);
        searchView.requestFocusFromTouch();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String query) {
                globalQuery = query;
                if (!TextUtils.isEmpty(query)) {
                    searchInCurrentFrag(query, searchVP2.getCurrentItem());
                }
                return true;
            }
        });
        return true;
    }

    private void searchInCurrentFrag(String query, int position) {
        if (query != null) {
            Fragment currentFragment = getSupportFragmentManager().findFragmentByTag("f" + position);
            if (currentFragment instanceof SearchUserFragment) {
                ((SearchUserFragment) currentFragment).searchUser(query);
            } else {
                ((SearchMessageFragment) currentFragment).searchMessage(query);
            }
        }
    }

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return true;
    }
}
也没有成功。与上述行为相同

在代码的当前状态下，我得到了NullPointerException（这是理所当然的）。当前代码使所有我的列表和视图都变为null，因为onCreateView（）由于已创建而未被触发

我只想能够从SearchActivity获取查询，以便从片段中完美地执行searchUser（）/searchMessage（）。

多亏@DanielNugent发布的最后一个链接，我已经能够解决这个问题

SearchUserFragment.java

public class SearchActivity extends AppCompatActivity {

    private static final int FRAG_USERS = 0;
    private static final int FRAG_MESSAGES = 1;
    private int currentFrag = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);
        setupActionBar();
        setupViewPager();
    }

    private void setupActionBar() {
        ActionBar actionBar = this.getSupportActionBar();
        actionBar.setTitle("");
        actionBar.setDisplayHomeAsUpEnabled(true);
    }

    private void setupViewPager() {
        ViewPager2 searchVP2 = findViewById(R.id.searchVP2);
        searchVP2.setAdapter(new SearchPagerAdapter(this));

        TabLayout searchTL = findViewById(R.id.searchTL);
        TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(searchTL, searchVP2, (tab, position) -> {
            switch (position) {
                case 0: {
                    tab.setText(R.string.users);
                    break;
                } case 1: {
                    tab.setText(R.string.messages);
                    break;
                }
            }
        });
        tabLayoutMediator.attach();

        searchTL.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                currentFrag = searchTL.getSelectedTabPosition();
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) { }
            @Override
            public void onTabReselected(TabLayout.Tab tab) { }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_searchable, menu);
        SearchView searchView = (SearchView) menu.findItem(R.id.searchIT).getActionView();
        searchView.setMaxWidth(Integer.MAX_VALUE);
        searchView.setIconified(false);
        searchView.setFocusable(true);
        searchView.requestFocusFromTouch();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String query) {
                if (!TextUtils.isEmpty(query)) {
                    if (currentFrag == FRAG_USERS) {
                        Bundle bundle = new Bundle();
                        bundle.putString(Constants.BUNDLE_SEARCH, query);
                        new SearchUserFragment().setArguments(bundle);
                        //SearchUserFragment.newInstance(query);
                    } else {
                        SearchMessageFragment.newInstance(query);
                    }
                }
                return true;
            }
        });
        return true;
    }

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return true;
    }
}

public class SearchPagerAdapter extends FragmentStateAdapter {

    public SearchPagerAdapter(@NonNull FragmentActivity fragmentActivity) {
        super(fragmentActivity);
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        if (position == 0) {
            return new SearchUserFragment();
        } else {
            return new SearchMessageFragment();
        }
    }

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

            @Override
            public boolean onQueryTextChange(String query) {
                if (!TextUtils.isEmpty(query)) {
                    if (currentFrag == FRAG_USERS) {
                        Bundle bundle = new Bundle();
                        bundle.putString(Constants.BUNDLE_SEARCH, query);
                        new SearchUserFragment().setArguments(bundle);
                    } else {
                        SearchMessageFragment.newInstance(query);
                    }
                }
                return true;
            }

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_search_message, container, false);
        notFoundTV = view.findViewById(R.id.notFoundTV);
        searchTipCV = view.findViewById(R.id.searchTipCV);
        refreshRV(view);
        Bundle bundle = this.getArguments();
        if (bundle != null) {
            searchUser(bundle.getString(BUNDLE_SEARCH));
        }
        return view;
    }

public class SearchActivity extends AppCompatActivity {

    private ViewPager2 searchVP2;
    private String globalQuery;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);
        setupActionBar();
        setupViewPager();
    }

    private void setupActionBar() {
        ActionBar actionBar = this.getSupportActionBar();
        actionBar.setTitle("");
        actionBar.setDisplayHomeAsUpEnabled(true);
    }

    private void setupViewPager() {
        searchVP2 = findViewById(R.id.searchVP2);
        searchVP2.setAdapter(new SearchPagerAdapter(this));

        TabLayout searchTL = findViewById(R.id.searchTL);
        TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(searchTL, searchVP2, (tab, position) -> {
            switch (position) {
                case 0: {
                    tab.setText(R.string.users);
                    break;
                }
                case 1: {
                    tab.setText(R.string.messages);
                    break;
                }
            }
        });
        tabLayoutMediator.attach();

        searchTL.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                searchInCurrentFrag(globalQuery, tab.getPosition());
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) { }
            @Override
            public void onTabReselected(TabLayout.Tab tab) { }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_searchable, menu);
        SearchView searchView = (SearchView) menu.findItem(R.id.searchIT).getActionView();
        searchView.setMaxWidth(Integer.MAX_VALUE);
        searchView.setIconified(false);
        searchView.setFocusable(true);
        searchView.requestFocusFromTouch();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String query) {
                globalQuery = query;
                if (!TextUtils.isEmpty(query)) {
                    searchInCurrentFrag(query, searchVP2.getCurrentItem());
                }
                return true;
            }
        });
        return true;
    }

    private void searchInCurrentFrag(String query, int position) {
        if (query != null) {
            Fragment currentFragment = getSupportFragmentManager().findFragmentByTag("f" + position);
            if (currentFragment instanceof SearchUserFragment) {
                ((SearchUserFragment) currentFragment).searchUser(query);
            } else {
                ((SearchMessageFragment) currentFragment).searchMessage(query);
            }
        }
    }

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return true;
    }
}
这可能会有所帮助，您基本上需要对现有片段的引用，并且您可以直接调用该方法，无需绑定：@DanielNugent我需要为ViewPager2设置适配器吗？我已经更改了SearchPagerAdapter的代码，但我不确定如何处理SearchActivity上的setupViewPager（）。当我尝试设置它时，它给了我一个错误，因为SearchPager类从FragmentPagerAdapter扩展而不是从FragmentStateAdapter扩展。请看这里的答案：@DanielNugent上一个链接就是我要找的。非常感谢：）