我正在尝试用点击按钮将当前片段替换为视图寻呼机中的新片段。
我尝试过各种方法，但却出现以下错误：
java.lang.NullPointerException：尝试在空对象引用上调用虚方法'void android.support.v4.view.ViewPager.setAdapter（android.support.v4.view.PagerAdapter）' at in.tvac.akshaye.lapitchat.PersonalDetailsFragment $ 1.onClick（PersonalDetailsFragment.java:92）
任何有上述错误解决方案的人都可以通过点击按钮来调用片段吗？
这是当前的片段代码
import android.app.ProgressDialog;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.design.widget.TextInputLayout;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseReference;
public class PersonalDetailsFragment extends Fragment {
private TextInputLayout mFirstName;
private TextInputLayout mInitials;
private TextInputLayout mLastName;
private Button mContinueBtn;
private RadioButton mFemale;
private RadioButton mMale;
private DatabaseReference mDatabase;
//ProgressDialog
private ProgressDialog mRegProgress;
private ViewPager mViewPager;
private SectionsPagerAdapter mSectionsPagerAdapter;
private TabLayout mTabLayout;
//Firebase Auth
private FirebaseAuth mAuth;
View view;
boolean male = true;
// private RadioGroup radioGroup;
public PersonalDetailsFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
view = inflater.inflate(R.layout.fragment_personal_details, container, false);
mRegProgress = new ProgressDialog(this.getActivity().getApplicationContext());
// Firebase Auth
mAuth = FirebaseAuth.getInstance();
mContinueBtn = (Button) view.findViewById(R.id.btnContinue);
mViewPager = (ViewPager) view.findViewById(R.id.main_tabPager);
mFirstName = (TextInputLayout) view.findViewById(R.id.inpuutCellNumber);
mInitials = (TextInputLayout) view.findViewById(R.id.inputHomeNumber);
mLastName = (TextInputLayout) view.findViewById(R.id.inputWorkNumber);
mContinueBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String first_Name = mFirstName.getEditText().getText().toString();
String initials = mInitials.getEditText().getText().toString();
String lastName = mLastName.getEditText().getText().toString();
if ( TextUtils.isEmpty( first_Name ) || TextUtils.isEmpty( initials ) || TextUtils.isEmpty( lastName ) )
{
Toast.makeText( getActivity().getApplicationContext(), "Make sure all fields are filled in.", Toast.LENGTH_LONG ).show();
}
//else {
//Tabs
mViewPager = (ViewPager) view.findViewById(R.id.main_tabPager);
mSectionsPagerAdapter = new SectionsPagerAdapter(new PersonalInforamtionFragment().getFragmentManager());
mViewPager.setAdapter(mSectionsPagerAdapter);
mTabLayout = (TabLayout) view.findViewById(R.id.main_tabs);
mTabLayout.setupWithViewPager(mViewPager);
// }
}
});
final RadioGroup radioGroup = (RadioGroup) view.findViewById(R.id.gender);
radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
switch (checkedId) {
case R.id.radioMale:
male = true;
break;
case R.id.radioFemale:
male = false;
break;
}
}
});
return view;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
// save views as variables in this method
// "view" is the one returned from onCreateView
// Android Fields
}
}
这是BankRegisterActivity
import android.content.Intent;
import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ServerValue;
public class BankRegisterActivity extends AppCompatActivity {
private FirebaseAuth mAuth;
private Toolbar mToolbar;
private ViewPager mViewPager;
private SectionsPagerAdapter mSectionsPagerAdapter;
private DatabaseReference mUserRef;
private TabLayout mTabLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bank_register);
mAuth = FirebaseAuth.getInstance();
mToolbar = (Toolbar) findViewById(R.id.main_page_toolbar);
setSupportActionBar(mToolbar);
getSupportActionBar().setTitle("ABSA Banking");
if (mAuth.getCurrentUser() != null) {
mUserRef = FirebaseDatabase.getInstance().getReference().child("Users").child(mAuth.getCurrentUser().getUid());
}
//Tabs
mViewPager = (ViewPager) findViewById(R.id.main_tabPager);
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
mViewPager.setAdapter(mSectionsPagerAdapter);
mTabLayout = (TabLayout) findViewById(R.id.main_tabs);
mTabLayout.setupWithViewPager(mViewPager);
}
@Override
public void onStart() {
super.onStart();
// Check if user is signed in (non-null) and update UI accordingly.
FirebaseUser currentUser = mAuth.getCurrentUser();
if(currentUser == null){
sendToStart();
} else {
mUserRef.child("online").setValue("true");
}
}
@Override
protected void onStop() {
super.onStop();
FirebaseUser currentUser = mAuth.getCurrentUser();
if(currentUser != null) {
mUserRef.child("online").setValue(ServerValue.TIMESTAMP);
}
}
private void sendToStart() {
Intent startIntent = new Intent(BankRegisterActivity.this, StartActivity.class);
startActivity(startIntent);
finish();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
getMenuInflater().inflate(R.menu.main_menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
super.onOptionsItemSelected(item);
if(item.getItemId() == R.id.main_logout_btn){
mUserRef.child("online").setValue(ServerValue.TIMESTAMP);
FirebaseAuth.getInstance().signOut();
sendToStart();
}
if(item.getItemId() == R.id.main_settings_btn){
}
if(item.getItemId() == R.id.main_all_btn){
}
return true;
}
}
这是SectionsPageAdapter代码：
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v7.widget.Toolbar;
class SectionsPagerAdapter extends FragmentPagerAdapter{
private Toolbar mToolbar;
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch(position) {
case 0:
PersonalDetailsFragment personalDetailsFragment = new PersonalDetailsFragment ();
return personalDetailsFragment;
case 1:
ContactDeatilsFragment contactDetailsFragment = new ContactDeatilsFragment ();
return contactDetailsFragment;
case 2:
PersonalInforamtionFragment personalInforamtionFragment = new PersonalInforamtionFragment ();
return personalInforamtionFragment;
case 3:
AccountInformationFragment accInformationFragment = new AccountInformationFragment();
return accInformationFragment;
case 4:
TCsFragment TCsFragment = new TCsFragment();
return TCsFragment;
default:
return null;
}
}
@Override
public int getCount() {
return 5;
}
public CharSequence getPageTitle(int position){
switch (position) {
case 0:
return "1";
case 1:
return "2";
case 2:
return "3";
case 3:
return "4";
case 4:
return "5";
default:
return null;
}
}
}
这是BankRegisterActivity的布局代码
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="in.tvac.akshaye.lapitchat.BankRegisterActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/appBarLayout">
<include layout="@layout/app_bar_layout" android:id="@+id/main_page_toolbar" />
<android.support.design.widget.TabLayout
android:id="@+id/main_tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"></android.support.design.widget.TabLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="@+id/main_tabPager"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/appBarLayout">
</android.support.v4.view.ViewPager>
</RelativeLayout>
答案 0 :(得分：0)
试试这个片段：
public class PersonalDetailsFragment extends Fragment implements View.OnClickListener {
private TextInputLayout mFirstName;
private TextInputLayout mInitials;
private TextInputLayout mLastName;
private Button mContinueBtn;
private RadioButton mFemale;
private RadioButton mMale;
private DatabaseReference mDatabase;
//ProgressDialog
private ProgressDialog mRegProgress;
private ViewPager mViewPager;
private SectionsPagerAdapter mSectionsPagerAdapter;
private TabLayout mTabLayout;
//Firebase Auth
private FirebaseAuth mAuth;
View v;
boolean male = true;
// private RadioGroup radioGroup;
public PersonalDetailsFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
v = inflater.inflate(R.layout.fragment_personal_details, container, false);
mRegProgress = new ProgressDialog(this.getActivity().getApplicationContext());
// Firebase Auth
mAuth = FirebaseAuth.getInstance();
mContinueBtn = (Button) v.findViewById(R.id.btnContinue);
mContinueBtn.setOnClickListener(this);
mViewPager = (ViewPager) getActivity().findViewById(R.id.main_tabPager);
mFirstName = (TextInputLayout) v.findViewById(R.id.inpuutCellNumber);
mInitials = (TextInputLayout) v.findViewById(R.id.inputHomeNumber);
mLastName = (TextInputLayout) v.findViewById(R.id.inputWorkNumber);
final RadioGroup radioGroup = (RadioGroup) view.findViewById(R.id.gender);
radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
switch (checkedId) {
case R.id.radioMale:
male = true;
break;
case R.id.radioFemale:
male = false;
break;
}
}
});
return v;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
// save views as variables in this method
// "view" is the one returned from onCreateView
// Android Fields
}
@Override
public void onClick(View v) {
if (v == mContinueBtn) {
String first_Name = mFirstName.getEditText().getText().toString();
String initials = mInitials.getEditText().getText().toString();
String lastName = mLastName.getEditText().getText().toString();
if ( TextUtils.isEmpty( first_Name ) || TextUtils.isEmpty( initials ) || TextUtils.isEmpty( lastName ) )
{
Toast.makeText( getActivity().getApplicationContext(), "Make sure all fields are filled in.", Toast.LENGTH_LONG ).show();
} else {
mViewPager.setCurrentItem(1);
}
}
}
}