您好,我正在尝试向我的活动添加imageslider,但出现错误
跟随this tutorial..
在这个位置,我在第45行收到此错误:
原因:java.lang.NullPointerException:尝试调用虚拟
方法“无效”
android.support.v4.view.ViewPager.setAdapter(android.support.v4.view.PagerAdapter)'
在空对象引用上
在第45行是:
sds.setAdapter(adapter);
这是我的actvity.java
public class Sayfalar extends AppCompatActivity implements View.OnClickListener {
private TabLayout tabLayout;
private ViewPager viewPager,sds;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sayfalar);
sds = (ViewPager) findViewById(R.id.resimler);
PagerAdapter adapter = new CustomAdapter(Sayfalar.this);
sds.setAdapter(adapter);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
}
public void showDialog (View v){
MyDialog dialog = new MyDialog();
dialog.show(getSupportFragmentManager(),"my_dialog");
}
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFrag(new Fragment1(), "Fragment1");
adapter.addFrag(new Fragment2(), "Fragment2");
adapter.addFrag(new Fragment3(), "Fragment3");
adapter.addFrag(new Fragment4(), "Fragment4");
adapter.addFrag(new Fragment5(), "Fragment5");
adapter.addFrag(new Fragment6(), "Fragment6");
adapter.addFrag(new Fragment7(), "Fragment7");
adapter.addFrag(new Fragment8(), "Fragment8");
adapter.addFrag(new Fragment9(), "Fragment9");
viewPager.setAdapter(adapter);
}
public void onClick(View view) {
}
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
public void addFrag(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
}
这是我的activity.xml
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/popupmenu"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.design.widget.TabLayout
android:id="@+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabMode="scrollable"/>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</android.support.design.widget.CoordinatorLayout>
如果我将此代码添加到我的activity.xml中,我会在所有片段中看到我的图片,但是我希望在一个片段中看到它。
这是代码:
<ImageView
android:id="@+id/resim"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
这是fragment.xml之一
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Kaynaklar.Agil">
<android.support.v4.view.ViewPager
android:id="@+id/resimler"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</RelativeLayout>
这是fragment1.java
public class Fragment1 extends Fragment {
public Fragment1 () {
// Required empty public constructor
}
@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
return inflater.inflate(R.layout.fragment1, container, false);
}
}
最佳答案
您可以检查此代码。
public class Sayfalar extends AppCompatActivity {
private TabLayout tabLayout;
private ViewPager viewPager,sds;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sayfalar);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
}
public void showDialog (View v){
MyDialog dialog = new MyDialog();
dialog.show(getSupportFragmentManager(),"my_dialog");
}
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(adapter);
}
public void onClick(View view) {
}
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
Fragment1 fragment1=Fragment1.newInstance(position);
return fragment1;
}
@Override
public int getCount() {
return 5;
}
public void addFrag(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
return "title "+position;
}
}
}
//分段
public class Fragment1 extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.fragment,container,false);
return view;
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
ImageView imageView= (ImageView) view.findViewById(R.id.imageview);
imageView.setImageResource(R.mipmap.ic_launcher);
}
public static Fragment1 newInstance(int position) {
Fragment1 fr=new Fragment1();
Bundle bundle=new Bundle();
bundle.putInt("position",position);
fr.setArguments(bundle);
return fr;
}
}
关于android - 如何在 fragment 中添加图像滑块,为什么会出现适配器(适配器)错误?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/37923409/