在 viewpager 中的片段之间传递字符串不能正常工作

Question

我的主 activity 有 3 个选项卡，每个选项卡加载不同的片段。我正在尝试将数据从片段 1 传递到片段 3，但它不起作用

可以加载所有 3 个片段，但问题是当我启动应用程序时只加载了 1 和 2。因此，当我运行应用程序并且我想将字符串从片段 1 传递到片段 3 时，它不起作用，因为它尚不存在。我该如何更改？

我正在使用 Eventbus (https://github.com/greenrobot/EventBus) 进行片段之间的通信。

public class MainActivity 扩展 AppCompatActivity {

    private Toolbar mToolbar;
    private TabLayout mTabLayout;
    private ViewPager mPager;
    private MyPagerAdapter mAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mAdapter = new MyPagerAdapter(getSupportFragmentManager());
        mToolbar = (Toolbar) findViewById(R.id.app_bar);
        setSupportActionBar(mToolbar);
        mTabLayout = (TabLayout) findViewById(R.id.tab_layout);

        mPager = (ViewPager) findViewById(R.id.pager);
        mPager.setAdapter(mAdapter);

        mTabLayout.setTabsFromPagerAdapter(mAdapter);

        mTabLayout.setupWithViewPager(mPager);
        mPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(mTabLayout));
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.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);
    }

    public static class MyFragment extends Fragment {
        public static final java.lang.String ARG_PAGE = "arg_page";

        public MyFragment() {
        }

        public static MyFragment newInstance(int pageNumber) {
            MyFragment myFragment = new MyFragment();
            Bundle arguments = new Bundle();
            arguments.putInt(ARG_PAGE, pageNumber + 1);
            myFragment.setArguments(arguments);
            return myFragment;
        }
    }



class MyPagerAdapter extends FragmentStatePagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
        Fragment fragment = MainActivity.MyFragment.newInstance(position); //FRAGMENT fragment;
        switch (position) {
            case 0:
                fragment = new Fragment1();
                break;
            case 1:
                fragment = new Fragment2();
                break;
            case 2:
                fragment = new Fragment3();
                break;
            default:
                break;
        }
        return fragment;
    }


    @Override
    public int getCount() {
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) { //set tab names

        switch (position) {
            case 0:
                return "Thread";
            case 1:
                return "AsyncTask";
            case 2:
                return "TODO";
        }
        return null;
    }}}

Answer 1

您希望适配器加载的最小页面数是这样设置的

Viewpager.setOffscreenPageLimit(3);

在 viewpager 中的片段之间传递字符串不能正常工作

Passing a string between fragments in a viewpager doesnt work properly

java

tabs

android

android-fragments