parcelable 오브젝트가 활동 수신시 null 인 이유는 무엇입니까?

Question

Android 개발자 가이드의 Parcelable 예제를 따라 다른 활동으로 보내는 좀 더 복잡한 객체를 사용하려고합니다. 바로 지금, 클래스는 String 멤버의 래퍼입니다. 개체를 의도에 넣고 의도 한대로 Intent에서 다시 읽으면받는 사람 쪽에서 항상 null 포인터입니다.

내 클래스 : 의도 읽기/백/만약 startActivity의

package com.mobibob.android.myapp; 

import android.os.Parcel; 
import android.os.Parcelable; 


public class ContentItem implements Parcelable { 
    public String name = "name"; 
    public static final String EXTRA_CONTENT_DETAIL = "contentDetail"; 

    ContentItem(String n) { 
     name = n; 
    } 

    ContentItem(Parcel in) { 
      in.readParcelable(ContentItem.class.getClassLoader()); <--- NEW CODE 
     name = in.readString(); 
    } 

    @Override 
    public String toString() { 
     return name.toString(); 
    } 

    @Override 
    public int describeContents() { 
     return 0; 
    } 

    @Override 
    public void writeToParcel(Parcel dest, int flags) { 
     dest.writeString(name); 
    } 

    public final Parcelable.Creator<ContentItem> CREATOR = new Parcelable.Creator<ContentItem>() { 
     public ContentItem createFromParcel(Parcel in) { 
     return new ContentItem(in); 
     } 

     public ContentItem[] newArray(int size) { 
     return new ContentItem[size]; 
     } 
    }; 

} 

내 설정 :

ContentItem ci = new ContentItem("mobibob"); 
// Launch ... 
Intent i = new Intent(getApplicationContext(), ContentDetailActivity.class); 
i.putExtra(ContentItem.EXTRA_CONTENT_DETAIL, ci); 
ContentItem readbackCi = i.getParcelableExtra(ContentItem.EXTRA_CONTENT_DETAIL); 
Log.d(TAG, "\n\n\t" + readbackCi.name); 
startActivity(i); 

내 수신 활동

package com.mobibob.android.myapp; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.util.Log; 
import android.widget.TextView; 

public class ContentDetailActivity extends Activity { 

    public static final String TAG = "ContentDetailActivity"; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
     setContentView(R.layout.content_detail); 

     try { 
      Intent i = getIntent(); 
      Log.d(TAG, "intent: " + i.toString()); 
      Log.d(TAG, "extras: " + i.getExtras()); 

      ContentItem ci = (ContentItem) i.getParcelableExtra(ContentItem.EXTRA_CONTENT_DETAIL); 

      Log.d(TAG, "content-item: " + ci.toString()); 

      ((TextView) findViewById(R.id.name_of_content)).setText(ci.name); 

     } catch (Exception e) { 
      Log.d(TAG, e.toString()); 
    } 
    } 

} 

내 로그 :

08-16 15:03:40.121 I/HomeActivity(9840): onItemClick - AdapterView (pos=1 id=1) 
08-16 15:03:40.121 D/HomeActivity(9840): 
08-16 15:03:40.121 D/HomeActivity(9840): 
08-16 15:03:40.121 D/HomeActivity(9840): Rock/Pop 
08-16 15:03:40.131 I/ActivityManager(1186): Starting activity: Intent { cmp=com.mobibob.android.myapp/.ContentDetailActivity (has extras) } 
08-16 15:03:40.341 D/ContentDetailActivity(9840): intent: Intent { cmp=com.mobibob.android.myapp/.ContentDetailActivity (has extras) } 
08-16 15:03:40.341 D/ContentDetailActivity(9840): extras: Bundle[mParcelledData.dataSize=148] 
08-16 15:03:40.351 D/ContentDetailActivity(9840): java.lang.NullPointerException 
08-16 15:03:40.653 I/ActivityManager(1186): Displayed activity com.mobibob.android.myapp/.ContentDetailActivity: 336 ms (total 336 ms) 

,

내 스택 백 트레이스는 :

08-16 17:19:52.170 I/HomeActivity(3147): onItemClick - AdapterView (pos=3 id=3) 
08-16 17:19:52.170 D/HomeActivity(3147): 
08-16 17:19:52.170 D/HomeActivity(3147): 
08-16 17:19:52.170 D/HomeActivity(3147): mobibob 
08-16 17:19:52.170 I/ActivityManager(1202): Starting activity: Intent { cmp=com.mobibob.android.myapp/.ContentDetailActivity (has extras) } 
08-16 17:19:52.410 D/ContentDetailActivity(3147): intent: Intent { cmp=com.mobibob.android.myapp/.ContentDetailActivity (has extras) } 
08-16 17:19:52.410 D/ContentDetailActivity(3147): extras: Bundle[mParcelledData.dataSize=144] 
08-16 17:19:52.410 D/ContentDetailActivity(3147): java.lang.NullPointerException 
08-16 17:19:52.410 W/System.err(3147): java.lang.NullPointerException 
08-16 17:19:52.420 W/System.err(3147):  at java.lang.reflect.Field.getField(Native Method) 
08-16 17:19:52.420 W/System.err(3147):  at java.lang.reflect.Field.get(Field.java:247) 
08-16 17:19:52.420 W/System.err(3147):  at android.os.Parcel.readParcelable(Parcel.java:1811) 
08-16 17:19:52.420 W/System.err(3147):  at android.os.Parcel.readValue(Parcel.java:1713) 
08-16 17:19:52.420 W/System.err(3147):  at android.os.Parcel.readMapInternal(Parcel.java:1947) 
08-16 17:19:52.420 W/System.err(3147):  at android.os.Bundle.unparcel(Bundle.java:169) 
08-16 17:19:52.420 W/System.err(3147):  at android.os.Bundle.getParcelable(Bundle.java:1037) 
08-16 17:19:52.430 W/System.err(3147):  at android.content.Intent.getParcelableExtra(Intent.java:3276) 
08-16 17:19:52.430 W/System.err(3147):  at com.mobibob.android.myapp.ContentDetailActivity.onCreate(ContentDetailActivity.java:24) 
08-16 17:19:52.430 W/System.err(3147):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
08-16 17:19:52.430 W/System.err(3147):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459) 
08-16 17:19:52.430 W/System.err(3147):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 
08-16 17:19:52.430 W/System.err(3147):  at android.app.ActivityThread.access$2200(ActivityThread.java:119) 
08-16 17:19:52.430 W/System.err(3147):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863) 
08-16 17:19:52.430 W/System.err(3147):  at android.os.Handler.dispatchMessage(Handler.java:99) 
08-16 17:19:52.430 W/System.err(3147):  at android.os.Looper.loop(Looper.java:123) 
08-16 17:19:52.430 W/System.err(3147):  at android.app.ActivityThread.main(ActivityThread.java:4363) 
08-16 17:19:52.430 W/System.err(3147):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-16 17:19:52.430 W/System.err(3147):  at java.lang.reflect.Method.invoke(Method.java:521) 
08-16 17:19:52.430 W/System.err(3147):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
08-16 17:19:52.430 W/System.err(3147):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
08-16 17:19:52.440 W/System.err(3147):  at dalvik.system.NativeStart.main(Native Method) 
08-16 17:19:52.895 I/ActivityManager(1202): Displayed activity com.mobibob.android.myapp/.ContentDetailActivity: 582 ms (total 582 ms) 

Answer 1

같아요 거라고 이미 in.readParcelable(ContentItem.class.getClassLoader()); 반환하여 다시의 ContentItem. 따라서이 선을 Parcelable.Creator의 createFromParcel-Method에 넣어야합니다. 그냥 추측.