Parcelable类是：
package mobile.bh.classes;
import java.util.List;
import mobile.bh.activities.MethodStep;
import android.content.Context;
import android.graphics.Bitmap;
import android.os.Parcel;
import android.os.Parcelable;
//simple class that just has one member property as an example
public class Recipe implements Parcelable {
public int id;
public String name;
public List<Ingredient> ingredients;
public List<MethodStep> method;
public String comment;
public String image;
public Bitmap image2;
Context mContext;
public Recipe(Context c){
mContext = c;
}
/* everything below here is for implementing Parcelable */
// 99.9% of the time you can just ignore this
public int describeContents() {
return 0;
}
// write your object's data to the passed-in Parcel
public void writeToParcel(Parcel out, int flags) {
out.writeInt(id);
out.writeString(name);
out.writeTypedList(ingredients);
out.writeTypedList(method);
out.writeString(comment);
out.writeString(image);
}
// this is used to regenerate your object. All Parcelables must have a CREATOR that implements these two methods
public static final Parcelable.Creator<Recipe> CREATOR = new Parcelable.Creator<Recipe>() {
public Recipe createFromParcel(Parcel in) {
return new Recipe(in);
}
public Recipe[] newArray(int size) {
return new Recipe[size];
}
};
// example constructor that takes a Parcel and gives you an object populated with it's values
private Recipe(Parcel in) {
id = in.readInt();
name =in.readString();
in.readTypedList(ingredients, Ingredient.CREATOR);
in.readTypedList(method, MethodStep.CREATOR);
comment = in.readString();
image = in.readString();
}
}
通过这样的意图发送数据：
Intent i = new Intent(context,RecipeInfoActivity.class);
ArrayList<Recipe> dataList = new ArrayList<Recipe>();
dataList.add(recipe);
i.putParcelableArrayListExtra("recipeObj", dataList);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(i);
并在其他地方接收数据，这使得NullPointerExceotion
ArrayList<Recipe> p = getIntent().getParcelableArrayListExtra("recipeObj");
LogCat输出：
08-24 16:37:51.172: E/AndroidRuntime(976): FATAL EXCEPTION: main
08-24 16:37:51.172: E/AndroidRuntime(976): java.lang.RuntimeException: Unable to start activity ComponentInfo{mobile.bh/mobile.bh.activities.RecipeInfoActivity}: java.lang.NullPointerException
08-24 16:37:51.172: E/AndroidRuntime(976): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Handler.dispatchMessage(Handler.java:99)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Looper.loop(Looper.java:123)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.app.ActivityThread.main(ActivityThread.java:4627)
08-24 16:37:51.172: E/AndroidRuntime(976): at java.lang.reflect.Method.invokeNative(Native Method)
08-24 16:37:51.172: E/AndroidRuntime(976): at java.lang.reflect.Method.invoke(Method.java:521)
08-24 16:37:51.172: E/AndroidRuntime(976): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
08-24 16:37:51.172: E/AndroidRuntime(976): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
08-24 16:37:51.172: E/AndroidRuntime(976): at dalvik.system.NativeStart.main(Native Method)
08-24 16:37:51.172: E/AndroidRuntime(976): Caused by: java.lang.NullPointerException
08-24 16:37:51.172: E/AndroidRuntime(976): at mobile.bh.classes.Recipe.<init>(Recipe.java:59)
08-24 16:37:51.172: E/AndroidRuntime(976): at mobile.bh.classes.Recipe.<init>(Recipe.java:56)
08-24 16:37:51.172: E/AndroidRuntime(976): at mobile.bh.classes.Recipe$1.createFromParcel(Recipe.java:47)
08-24 16:37:51.172: E/AndroidRuntime(976): at mobile.bh.classes.Recipe$1.createFromParcel(Recipe.java:1)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Parcel.readParcelable(Parcel.java:1906)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Parcel.readValue(Parcel.java:1771)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Parcel.readListInternal(Parcel.java:2017)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Parcel.readArrayList(Parcel.java:1461)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Parcel.readValue(Parcel.java:1792)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Parcel.readMapInternal(Parcel.java:2008)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Bundle.unparcel(Bundle.java:208)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.os.Bundle.getParcelableArrayList(Bundle.java:1144)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.content.Intent.getParcelableArrayListExtra(Intent.java:3424)
08-24 16:37:51.172: E/AndroidRuntime(976): at mobile.bh.activities.RecipeInfoActivity.onCreate(RecipeInfoActivity.java:56)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
08-24 16:37:51.172: E/AndroidRuntime(976): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
08-24 16:37:51.172: E/AndroidRuntime(976): ... 11 more
答案 0 :(得分：0)
这是我使用Parcelable实施Lists的方式：
public String tag;
public int success;
public int error;
public User user;
public Event event;
public String error_message;
public List<Event> finishedevents;
public List<Leadevent> leaderboard;
public List<User> user_search;
public void readFromParcel(Parcel in) {
tag = in.readString();
success = in.readInt();
error = in.readInt();
user = (User) in.readValue(User.class.getClassLoader());
event = (Event) in.readValue(Event.class.getClassLoader());
finishedevents = (ArrayList<Event>) in.readSerializable();
leaderboard = (ArrayList<Leadevent>) in.readSerializable();
user_search = (ArrayList<User>) in.readSerializable();
error_message = in.readString();
}
public void writeToParcel(Parcel out, int content) {
// TODO Auto-generated method stub
out.writeString(tag);
out.writeInt(success);
out.writeInt(error);
out.writeValue(user);
out.writeValue(event);
out.writeList(finishedevents);
out.writeList(leaderboard);
out.writeList(user_search);
out.writeString(error_message);
}
因此，您应该readSerializable()尝试Lists。