java - 在 fragment Android中设置自定义字体时出现异常错误

这是代码，它基本上是一个简单的菜单驱动的应用程序，我试图在一个片段中使用自定义字体，这导致了一个问题。
我已经在一个活动中成功地使用了这个字体，这个菜单活动启动了另一个活动，在这个活动中这个片段被膨胀。
我不确定这是否是导致问题的原因，所以请帮我。

package com.cbs.CoronaTheCarnival;

    import android.app.Fragment;
    import android.graphics.Typeface;
    import android.os.Bundle;
    import android.view.View;
    import android.view.LayoutInflater;
    import android.view.ViewGroup;
    import android.widget.TextView;


    /**
     * Created by aditya on 2/4/14.
     */
    public class AboutFragment extends Fragment{

        View rootView;
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
            View rootView = inflater.inflate(R.layout.fragment_about, container, false);
            initFonts();
            return rootView;

        }

         public void initFonts(){

            TextView tv_title = (TextView) rootView.findViewById(R.id.tv_about_title);
            Typeface changeFont = Typeface.createFromAsset(getActivity().getAssets(), "TRACK.OTF");
            tv_title.setTypeface(changeFont);
            TextView tv_theme = (TextView) rootView.findViewById(R.id.tv_about_theme);
            tv_theme.setTypeface(changeFont);

        }


    }

这是logcat，它说异常错误，我不知道它为什么不工作，请帮帮我，它杀了我，凌晨4点21分。

02-06 04:19:41.534    3591-3591/com.cbs.CoronaTheCarnival E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.cbs.CoronaTheCarnival/com.cbs.CoronaTheCarnival.HomeActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5041)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.cbs.CoronaTheCarnival.AboutFragment.initFonts(AboutFragment.java:27)
            at com.cbs.CoronaTheCarnival.AboutFragment.onCreateView(AboutFragment.java:20)
            at android.app.Fragment.performCreateView(Fragment.java:1695)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:885)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1057)
            at android.app.BackStackRecord.run(BackStackRecord.java:682)
            at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1435)
            at android.app.Activity.performStart(Activity.java:5113)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2153)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5041)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
            at dalvik.system.NativeStart.main(Native Method)

最佳答案

在initfonts方法中，可以执行以下操作：

TextView tv_title = (TextView) rootView.findViewById(R.id.tv_about_title);

这里，rootview为空，因为它从未正确初始化。您似乎混淆了两个rootview变量：

View rootView; // this is one variable
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        View rootView = inflater.inflate(R.layout.fragment_about, container, false);
        // this is not the same rootView !
        // here, rootView != this.rootView
        initFonts();
        return rootView;
    }

public void initFonts(){
    TextView tv_title = (TextView) rootView.findViewById(R.id.tv_about_title);
    // this is like using this.rootView.findViewById
    // ...
}

initfonts方法看不到oncreateview方法中的rootview，因此它将使用您在oncreateview上声明的视图，第一个视图从未正确初始化。要解决此问题，可以将initfonts的代码移回oncreateview中，将视图作为initfonts方法的参数传递，或在oncreateview中初始化变量，如下所示：

this.rootView = rootView;