java - 为应用介绍创建滑动 fragment

Question

我有一个项目，我正在为其制作可滑动的介绍，用户基本上滑动四个页面，向他/她介绍应用程序并解释其功能等。但是，我不断收到以下错误:

 android.content.res.Resources$NotFoundException: Resource ID #0x0
 at android.content.res.Resources.getValue(Resources.java:1351)
 at android.content.res.Resources.loadXmlResourceParser(Resources.java:2774)
 at android.content.res.Resources.getLayout(Resources.java:1165)
 at android.view.LayoutInflater.inflate(LayoutInflater.java:421)
 at com.scyon.gradebook.WelcomeFragment.onCreateView(WelcomeFragment.java:40)
 at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
 at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
 at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1248)
 at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
 at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1613)
 at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:570)
 at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
 at android.support.v4.view.ViewPager.populate(ViewPager.java:1106)
 at android.support.v4.view.ViewPager.populate(ViewPager.java:952)
 at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1474)
 at android.view.View.measure(View.java:18788)
 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
 at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:610)
 at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:677)
 at android.view.View.measure(View.java:18788)
 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
 at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
 at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
 at android.view.View.measure(View.java:18788)
 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
 at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
 at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
 at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
 at android.view.View.measure(View.java:18788)
 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
 at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
 at android.view.View.measure(View.java:18788)
 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
 at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
 at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
 at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
 at android.view.View.measure(View.java:18788)
 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
 at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
 at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2643)
 at android.view.View.measure(View.java:18788)
 at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2100)
 at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1216)
 at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1452)
 at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
 at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013)
 at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
 at android.view.Choreographer.doCallbacks(Choreographer.java:670)
 at android.view.Choreographer.doFrame(Choreographer.java:606)
 at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
 at android.os.Handler.handleCallback(Handler.java:739)
 at android.os.Handler.dispatchMessage(Handler.java:95)
 at android.os.Looper.loop(Looper.java:148)
 at android.app.ActivityThread.main(ActivityThread.java:5417)
 at java.lang.reflect.Method.invoke(Native Method)
 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
 at com.android.internal.os.Zygote

我的项目组织如下:

我有我的 IntroActivity:

public class IntroActivity extends AppCompatActivity {

private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;

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

    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    mViewPager = (ViewPager) findViewById(R.id.container);
    mViewPager.setAdapter(mSectionsPagerAdapter);

}

public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int position) {

        if (position == 0) {

            return new WelcomeFragment().newInstance("testtitle#1",R.layout.fragment_welcome_one,R.id.welcome1);

        }else if (position == 1){

            return new WelcomeFragment().newInstance("testtitle#2", R.layout.fragment_welcome_two, R.id.welcome2);

        }else if (position == 2){

            return new WelcomeFragment().newInstance("testtitle#3", R.layout.fragment_welcome_three, R.id.welcome3);

        }else if (position == 3){

            return new WelcomeFragment().newInstance("testtitle#4", R.layout.fragment_welcome_four, R.id.welcome4);

        }

        return null;
    }

    @Override
    public int getCount() {
        return 4;
    }

}
}

最后我有了我的 WelcomeFragment 模型类:

public class WelcomeFragment extends Fragment {

String mTitle;
int mLayoutID;
int mTitleID;

public WelcomeFragment() {

}

public WelcomeFragment newInstance(String title, int layoutID, int titleID) {

    WelcomeFragment mWelcomeFragment = new WelcomeFragment();

    mTitle = title;
    mLayoutID = layoutID;
    mTitleID = titleID;

    return mWelcomeFragment;
}

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View rootView = inflater.inflate(mLayoutID,container,false);
    TextView textView = (TextView)rootView.findViewById(mTitleID);
    Typeface font = Typeface.createFromAsset(getActivity().getAssets(), "fonts/Roboto-Thin.ttf");
    textView.setText(mTitle);
    textView.setTypeface(font);

    return rootView;
}
}

如有任何帮助，我们将不胜感激。我检查了我的代码好几次，我发现资源 ID 应该是空的，但我不明白为什么会这样。

Answer 1

问题在于，除了 newInstance() 之外，您还调用了默认构造函数，因此您连续创建了两个 Fragment，而第一个没有布局 ID。

将 newInstance() 方法设为静态，这样您就不必为了调用 newInstance() 方法而创建虚拟对象:

public static WelcomeFragment newInstance(String title, int layoutID, int titleID) {

    WelcomeFragment mWelcomeFragment = new WelcomeFragment();

    mTitle = title;
    mLayoutID = layoutID;
    mTitleID = titleID;

    return mWelcomeFragment;
}

然后，将其作为静态方法调用，而不是调用 new WelcomeFragment():

@Override
public Fragment getItem(int position) {

    if (position == 0) {

        return WelcomeFragment.newInstance("testtitle#1",R.layout.fragment_welcome_one,R.id.welcome1);

    }else if (position == 1){

        return WelcomeFragment.newInstance("testtitle#2", R.layout.fragment_welcome_two, R.id.welcome2);

    }else if (position == 2){

        return WelcomeFragment.newInstance("testtitle#3", R.layout.fragment_welcome_three, R.id.welcome3);

    }else if (position == 3){

        return WelcomeFragment.newInstance("testtitle#4", R.layout.fragment_welcome_four, R.id.welcome4);

    }

    return null;
}