android - 将数据从 Activity 发送到 Tab Fragment

Question

我的代码有一个小问题，我在这个网站上搜索但仍然没有找到最佳答案我会将数据发送到我的标签 fragment ，这是我的代码

我的 Activity 类

public class MainActivity extends AppCompatActivity 

    private ViewPager pager;
    private Toolbar toolbar;
    private TabLayout tabs;

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


        pager=(ViewPager) findViewById(R.id.pager);
        tabs=(TabLayout) findViewById(R.id.tabs);

        pager.setAdapter(new TabFragmentPagerAdapter(getSupportFragmentManager()));
        tabs.setupWithViewPager(pager);
        tabs.setTabGravity(TabLayout.GRAVITY_FILL);

        Bundle bundle = new Bundle();
        bundle.putString("edttext", "data From Activity");
        // set Fragmentclass Arguments
        tab1Fragment fragobj = new tab1Fragment();
        fragobj.setArguments(bundle);

    }
}

这是我的 tab1 类

public class tab1Fragment extends Fragment 

    public tab1Fragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        View view= inflater.inflate(R.layout.fragment_tab1, container, false);
        TextView tes=(TextView) view.findViewById(R.id.testtab1);
        String strtext = getArguments().getString("edttext");

        tes.setText("tes :"+ strtext);
        return  view;
    }
}

还有这个我的页面 fragment 适配器

public class TabFragmentPagerAdapter extends FragmentPagerAdapter 

    String[] title = new String[]{
            "Tab 1", "Tab 2", "Tab 3"
    };

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

    @Override
    public Fragment getItem(int position){
        Fragment fragment=null;
        switch (position){
            case 0:
                fragment=new tab1Fragment();
                break;
            case 1:
                fragment=new tab2Fragment();
                break;
            case 2:
                fragment=new tab3Fragment();
                break;
            default:
                fragment=null;
                break;
        }
        return  fragment;
    }
    @Override
    public  CharSequence getPageTitle(int position){
        return  title[position];
    }
    @Override
    public  int getCount(){
        return  title.length;
    }
}

当我运行错误时

java.lang.NullPointerException

请帮忙

Answer 1

在您的 AppCompatActivity 中，您已发送

tab1Fragment fragobj = new tab1Fragment();
fragobj.setArguments(bundle);

但是在你的TabFragmentPagerAdapter

fragment=new tab1Fragment();
            break;

它有空参数

内部开关

switch (position){
    case 0:
      fragment=new tab1Fragment();               
      Bundle bundle = new Bundle();
      bundle.putString("edttext", "data From Activity");
      fragment.setArguments(bundle);
    break;