我正在尝试使用Date类将另一个实例写入文件实例的另一个类中的CompanySaver类。 Date类是Calendar类的子类，该类实现java.io.Serializable，除了从Calendar类继承的3个整数外，没有任何实例变量。类和堆栈跟踪在下面。
堆栈跟踪：
java.io.NotSerializableException: Investment.Date
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at java.util.ArrayList.writeObject(ArrayList.java:762)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1028)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at Investment.CompanySaver.save(CompanySaver.java:32)
at Investment.Investment.main(Investment.java:25)
日历类别：
public class Calendar implements Serializable
{
protected int month;
protected int day;
protected int year;
protected int maxDay;
protected static final long serialVersionUID = 2L;
public void checkMaxDay()
{
if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
maxDay = 31;
else if (month == 2)
maxDay=28;
else if (year % 4 == 0 && month == 2)
maxDay=29;
else
maxDay=30;
if(day>maxDay)
day = maxDay;
}
public void checkMaxMonth()
{
if(month>12)
month=12;
}
}
Date Class：
package Investment;
public class Date extends Calendar
{
Date()
Date(int month, int day, int year)
{
if(month<13 && month>0)
this.month = month;
else
throw new IllegalArgumentException("Month must be between 1 and 12");
if(day<32 && day>0)
this.day = day;
else
throw new IllegalArgumentException("Day must be between 1 and 31");
if(year>2000)
this.year = year-2000;
else
this.year = year;
checkMaxDay();
}
public String getDate() {return String.valueOf(month)+"/"+String.valueOf(day)+"/"+String.valueOf(year);}
public void setDate(int month, int day, int year)
{
if(month<13 && month>0)
this.month = month;
else
throw new IllegalArgumentException("Month must be between 1 and 12");
if(day<32 && day>0)
this.day = day;
else
throw new IllegalArgumentException("Day must be between 1 and 31");
if(year>2000)
this.year = year-2000;
else
this.year = year;
checkMaxDay();
}
public int getYear() {return year;}
public int getMonth() {return month;}
public int getDay() {return day;}
public void setYear(int year) {this.year = year;}
public void setMonth(int month)
{
if(month<13 && month>0)
this.month = month;
else
throw new IllegalArgumentException("Month must be between 1 and 12");
}
public void setDay(int day)
{
this.day = day;
checkMaxDay();
}
public boolean equals(Date date)
{
if(date.getDay() == this.day && date.getMonth() == this.month && date.getYear() == this.year)
return true;
else
return false;
}
public void subtract(int num, String unit)
// Does not support +/- days
{
if(unit.equalsIgnoreCase("months"))
{
if(num<month)
month = month-num;
else if (num == month)
{
year--;
month = 12;
}
else if (num<12)
{
year--;
month = 12 -(num-month);
}
else if (num == 12)
{
year--;
}
else
{
year = year - (num/12);
int num2 = num % 12;
if(num2<month)
month = month-num2;
else if (num2 == month)
{
year--;
month = 12;
}
else
{
year--;
month = 12-(num2-month);
}
}
checkMaxDay();
day=maxDay;
}
if(unit.equalsIgnoreCase("days"))
{
System.out.println("Date math does not support adding/subtracting days yet");
}
if(unit.equalsIgnoreCase("years"))
{
year = year - num;
if(year<0)
year = 0;
}
checkMaxDay();
checkMaxMonth();
}
public void add(int num, String unit)
{
if(unit.equalsIgnoreCase("months"))
{
if(num + month <= 12)
month = num + month;
else if(num<=12)
{
year++;
month = (month+num)-12;
}
else
{
int num2 = (num) % 12;
year = year + (num/12);
if(month + num2 >= 12)
{
year++;
month = (month+num2)-12;
}
else
month = month + num2;
}
}
if(unit.equalsIgnoreCase("days"))
{
System.out.println("Date math does not support adding/subtracting days yet");
}
if(unit.equalsIgnoreCase("years"))
{
year = year + num;
}
checkMaxDay();
checkMaxMonth();
}
}
CompanySaver类别：
package Investment;
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
public class CompanySaver
{
private static final String filepath="C:\\Users\\Masiah\\Documents\\GitHUb\\Investments\\Companies\\";
public static void save(Company comp)
{
try
{
FileOutputStream fileOut = new FileOutputStream(filepath+comp.getName());
ObjectOutputStream objectOut = new ObjectOutputStream(fileOut);
objectOut.writeObject(comp);
objectOut.close();
}
catch (Exception ex)
{
ex.printStackTrace();
}
}
public static void save(Retail comp)
{
try
{
FileOutputStream fileOut = new FileOutputStream(filepath+comp.getName());
ObjectOutputStream objectOut = new ObjectOutputStream(fileOut);
objectOut.writeObject(comp);
objectOut.close();
}
catch (Exception ex)
{
ex.printStackTrace();
}
}
}
尝试在java.io.Serializable类中实现Date。否则，我会找到类似的帖子：https://stackoverflow.com/a/28080877/13113414
可能您的课程过时。尝试清理您的构建目录并重新构建项目。