我有一个扩展Parcelable的类。它有一个成员变量，它是另一个类的ArrayList，它也扩展了Parcelable。
我将Intent中的MyClass1对象传递回Activity并将其读入。当构造函数到达in.readTypedList时，应用程序崩溃并出现以下错误：
04-11 14:19:11.223: E/AndroidRuntime(502): Uncaught handler: thread main exiting due to uncaught exception
04-11 14:19:11.234: E/AndroidRuntime(502): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=0, result=-1, data=Intent { (has extras) }} to activity {com.mypackage.app/com.mypackage.app.activity.MyActivity}: java.lang.NullPointerException
04-11 14:19:11.234: E/AndroidRuntime(502): at android.app.ActivityThread.deliverResults(ActivityThread.java:3329)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.app.ActivityThread.handleSendResult(ActivityThread.java:3371)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.app.ActivityThread.access$2700(ActivityThread.java:119)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1893)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.os.Handler.dispatchMessage(Handler.java:99)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.os.Looper.loop(Looper.java:123)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.app.ActivityThread.main(ActivityThread.java:4363)
04-11 14:19:11.234: E/AndroidRuntime(502): at java.lang.reflect.Method.invokeNative(Native Method)
04-11 14:19:11.234: E/AndroidRuntime(502): at java.lang.reflect.Method.invoke(Method.java:521)
04-11 14:19:11.234: E/AndroidRuntime(502): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
04-11 14:19:11.234: E/AndroidRuntime(502): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
04-11 14:19:11.234: E/AndroidRuntime(502): at dalvik.system.NativeStart.main(Native Method)
04-11 14:19:11.234: E/AndroidRuntime(502): Caused by: java.lang.NullPointerException
04-11 14:19:11.234: E/AndroidRuntime(502): at android.os.Parcel.readTypedList(Parcel.java:1497)
04-11 14:19:11.234: E/AndroidRuntime(502): at com.mypackage.app.utils.Strength.<init>(Strength.java:44)
04-11 14:19:11.234: E/AndroidRuntime(502): at com.mypackage.app.utils.Strength$1.createFromParcel(Strength.java:171)
04-11 14:19:11.234: E/AndroidRuntime(502): at com.mypackage.app.utils.Strength$1.createFromParcel(Strength.java:1)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.os.Parcel.readParcelable(Parcel.java:1845)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.os.Parcel.readValue(Parcel.java:1713)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.os.Parcel.readMapInternal(Parcel.java:1947)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.os.Bundle.unparcel(Bundle.java:169)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.os.Bundle.containsKey(Bundle.java:210)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.content.Intent.hasExtra(Intent.java:3067)
04-11 14:19:11.234: E/AndroidRuntime(502): at com.mypackage.app.activity.MyActivity.onActivityResult(MyActivity.java:306)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.app.Activity.dispatchActivityResult(Activity.java:3828)
04-11 14:19:11.234: E/AndroidRuntime(502): at android.app.ActivityThread.deliverResults(ActivityThread.java:3325)
04-11 14:19:11.234: E/AndroidRuntime(502): ... 11 more
public class MyClass1 implements Parcelable {
private int mVar1;
private int mVar2;
private int mVar3;
private long mVar5;
private long mVar6;
private String mVar7;
private String mVar8;
private String mVar9;
private String mVar10;
private ArrayList<MyClass2> mVar11;
public MyClass1() {
mVar1 = -1;
mVar2 = -1;
mVar3 = -1;
mVar5 = 0;
mVar6 = 0;
mVar7 = null;
mVar8 = null;
mVar9 = null;
mVar10 = null;
mVar11 = new ArrayList<MyClass2>();
}
public MyClass1(Parcel in) {
mVar1 = in.readInt();
mVar2 = in.readInt();
mVar3 = in.readInt();
mVar5 = in.readLong();
mVar6 = in.readLong();
mVar8 = in.readString();
mVar9 = in.readString();
mVar10 = in.readString();
in.readTypedList(mVar11, MyClass2.CREATOR);
mVar7 = in.readString();
}
public int getVar1() {
return mVar1;
}
public void setVar1(int intVar1) {
this.mVar1 = intVar1;
}
public int getVar2() {
return mVar2;
}
public void setVar2(int intVar2) {
this.mVar2 = intVar2;
}
public int getVar3() {
return mVar3;
}
public void setVar3(int intVar3) {
this.mVar3 = intVar3;
}
public long getVar5() {
return mVar5;
}
public void setVar5(long lngVar5) {
this.mVar5 = lngVar5;
}
public long getVar6() {
return mVar6;
}
public void setVar6(long lngVar6) {
this.mVar6 = lngVar6;
}
public String getVar7() {
return mVar7;
}
public void setVar7(String strVar7) {
this.mVar7 = strVar7;
}
public String getVar8() {
return mVar8;
}
public void setVar8(String strVar8) {
this.mVar8 = strVar8;
}
public String getVar9() {
return mVar9;
}
public void setVar9(String strVar9) {
this.mVar9 = strVar9;
}
public String getVar10() {
return mVar10;
}
public void setVar10(String strVar10) {
this.mVar10 = strVar10;
}
public ArrayList<MyClass2> getVar11() {
return mVar11;
}
public void setVar11(ArrayList<MyClass2> aryVar11) {
this.mVar11 = aryVar11;
}
public void addVar11(MyClass2 mc2) {
this.mVar11.add(mc2);
}
public MyClass2 removeVar11(int index) {
if (index < this.mVar11.size()) {
return this.mVar11.remove(index);
}
return null;
}
public static final Parcelable.Creator<MyClass1> CREATOR = new Parcelable.Creator<MyClass1>()
{
public MyClass1 createFromParcel(Parcel in) {
return new MyClass1(in);
}
public MyClass1[] newArray (int size) {
return new MyClass1[size];
}
};
public int describeContents() {
return 0;
}
public void writeToParcel (Parcel dest, int flags) {
dest.writeInt(mVar1);
dest.writeInt(mVar2);
dest.writeInt(mVar3);
dest.writeLong(mVar5);
dest.writeLong(mVar6);
dest.writeString(mVar8);
dest.writeString(mVar9);
dest.writeString(mVar10);
if (mVar11 == null) {
mVar11 = new ArrayList<MyClass2>();
}
dest.writeTypedList(mVar11);
dest.writeString(mVar7);
}
}
public class MyClass2 implements Parcelable {
private int mVar1;
private int mVar2;
private String mVar3;
private String mVar4;
public MyClass2() {
mVar1 = -1;
mVar2 = -1;
mVar3 = null;
mVar4 = null;
}
public MyClass2(Parcel in) {
mVar1 = in.readInt();
mVar2 = in.readInt();
mVar3 = in.readString();
mVar4 = in.readString();
}
public int getVar1() {
return mVar1;
}
public void setVar1(int intVar1) {
this.mVar1 = intVar1;
}
public int getVar2() {
return mVar2;
}
public void setVar2(int intVar2) {
this.mVar2 = intVar2;
}
public String getVar3() {
return mVar3;
}
public void setVar3(String strVar3) {
this.mVar3 = strVar3;
}
public String getVar4() {
return mVar4;
}
public void setVar4(String strVar4) {
this.mVar4 = strVar4;
}
public static final Parcelable.Creator<MyClass2> CREATOR = new Parcelable.Creator<MyClass2>()
{
public MyClass2 createFromParcel(Parcel in) {
return new MyClass2(in);
}
public MyClass2[] newArray (int size) {
return new MyClass2[size];
}
};
public int describeContents() {
return 0;
}
public void writeToParcel (Parcel dest, int flags) {
dest.writeInt(mVar1);
dest.writeInt(mVar2);
dest.writeString(mVar3);
dest.writeString(mVar4);
}
}
我已经梳理了这个，看不到任何东西，这意味着我可能没有注意到它真的很蠢。
想法？
答案 0 :(得分：10)
04-11 14:19:11.234: E/AndroidRuntime(502): Caused by: java.lang.NullPointerException
04-11 14:19:11.234: E/AndroidRuntime(502): at android.os.Parcel.readTypedList(Parcel.java:1497)
查看源代码（Parcel.java:1497）：
public final <T> void readTypedList(List<T> list, Parcelable.Creator<T> c) {
int M = list.size(); // line 1497
... ...
的ArrayList＆LT; MyClass2＆GT;在调用Parcel.readTypedList（）;
之前，mVar11尚未正确初始化public MyClass1(Parcel in) {
mVar1 = in.readInt();
mVar2 = in.readInt();
mVar3 = in.readInt();
mVar5 = in.readLong();
mVar6 = in.readLong();
mVar8 = in.readString();
mVar9 = in.readString();
mVar10 = in.readString();
mVar11 = new ArrayList<MyClass2>();
in.readTypedList(mVar11, MyClass2.CREATOR);
mVar7 = in.readString();
}
这应该可以解决您的NullPointerException错误。