2

我遇到了一个问题，即Object从 a 实例化 aParcel会抛出NullPointerException. My Class Contact实现Parcelable，包含一个 CREATOR，并且所有连接似乎都有效。Contact对象表示通讯簿中的联系人。使用的变量有以下类型：

String firstName, lastName, note;
List<String> emails, phones;

构造函数将所有字符串初始化为 "" 并将所有列表初始化为空列表。和方法writeToParcel如下Contact(Parcel in)所示：

public void writeToParcel(Parcel out, int flags) {
    out.writeString(firstName);
    out.writeString(lastName);

    //If there are emails, write a 1 followed by the list. Otherwise, write a 0
    if (!emails.isEmpty())
    {
        out.writeInt(1);
        out.writeStringList(emails);
    }
    else
        out.writeInt(0);

    //If there are phone numbers, write a 1 followed by the list. Otherwise, write a 0
    if (!phones.isEmpty())
    {
        out.writeInt(1);
        out.writeStringList(phones);
    }
    else
        out.writeInt(0);
    out.writeString(note);
}

...

public Contact(Parcel in)
{
    firstName = in.readString();
    Log.i(TAG, firstName);
    lastName = in.readString();
    Log.i(TAG, lastName);
    int emailsExist = in.readInt();
    if (emailsExist == 1)
        in.readStringList(emails);
    else
        emails = new ArrayList<String>();
    int phonesExist = in.readInt();
    if (phonesExist == 1)
        in.readStringList(phones);//Line 80, where this app breaks
    else
        phones = new ArrayList<String>();
    note = in.readString();
}

我目前正在进行的测试提供了有效的名字和姓氏、一个电话号码和一张便条。我在打包这个包裹时得到的相关输出如下：

FATAL EXCEPTION: main
java.lang.RuntimeException: Failure delivering result ResultInfo...
...
Caused by: java.lang.NullPointerException
    at android.os.Parcel.readStringList(Parcel.java:1718)
    at com.mycompany.android.Contact.<init>(Contact.java:80) //This is the line marked above
    at com.mycompany.android.Contact$1.createFromParcel(Contact.java:40) //This is inside the CREATOR
    ...

我做错了什么？数字不能写成字符串列表，还是我做错了什么？

4

1 回答 1

2

我只是多戳了几分钟，才意识到我的错误。该readStringList方法不能接收空参数。我的新Contact(Parcel in)方法如下：

public Contact(Parcel in)
{
    firstName = in.readString();
    Log.i(TAG, firstName);
    lastName = in.readString();
    Log.i(TAG, lastName);
    int emailsExist = in.readInt();
    emails = new ArrayList<String>();
    if (emailsExist == 1)
        in.readStringList(emails);
    int phonesExist = in.readInt();
    phones = new ArrayList<String>();
    if (phonesExist == 1)
        in.readStringList(phones);          
    note = in.readString();
}
于 2012-10-19T18:19:05.357 回答