當我嘗試運行此代碼時,它向我顯示一個異常,它是「nullPointer異常」。我找不到這個代碼的錯誤,任何人都可以幫我修復這個錯誤嗎?我的代碼很受歡迎,請幫我修復它。如何發送字符串從活動到使用包的片段
這裏是我的MainActivity
public class MainActivity extends AppCompatActivity {
private TabLayout tabLayout;
private ViewPager viewPager;
EditText testInputTV;
Button send;
Bundle bundle;
String welcome ="Welcome";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
testInputTV = (EditText) findViewById(R.id.testInput);
send= (Button) findViewById(R.id.send);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
}
public void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
bundle =new Bundle();
bundle.putString("welcome", welcome);
FragmentOne fragobj = new FragmentOne();
fragobj.setArguments(bundle);
adapter.addFragment(new FragmentOne(), "ONE");
viewPager.setAdapter(adapter);
}
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(android.support.v4.app.FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
}
我的片段類logcat的
public class FragmentOne extends Fragment {
String storeText;
private Bundle bundle;
public FragmentOne() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view=inflater.inflate(R.layout.fragment_fragment_one, container, false);
bundle = this.getArguments();
storeText = bundle.getString("welcome");
Toast.makeText(getContext().getApplicationContext(),storeText,Toast.LENGTH_SHORT).show();
return view;
}
}
錯誤文本
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
什麼生產線引發此異常? – Acapulco
將'adapter.addFragment(new FragmentOne(),「ONE」);'改爲'adapter.addFragment(fragobj,「ONE」);'。 –
storeText = bundle.getString(「welcome」);這一行使例外 –