我的主要活动有3个标签,每个标签加载一个不同的片段。我正在尝试将数据从片段1传递到片段3,但是它不起作用
可以加载所有3个片段,但是问题是我启动应用程序时仅加载了1&2。因此,当我运行该应用程序时,我想将字符串从片段1传递到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。
公共类MainActivity扩展了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;
}}}
您希望适配器加载的最小页面数是这样设置的
Viewpager.setOffscreenPageLimit(3);
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