import java.io.Serializable;
@SuppressWarnings("serial")
public class Person implements Serializable
{
private String firstname;
private String lastname;
private int age;
public Person (String PersonFN, String PersonLN, int PersonA)
{
firstname = PersonFN;
lastname = PersonLN;
age = PersonA;
}
public String toString()
{
return "Name: "+firstname+" "+lastname+" Age: "+age;
}
public int getAge()
{
return age;
}
}
另一个，完成所有工作：
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.*;
public class Collection
{
int min;
int max;
int total;
private static ArrayList<Person> people;
public Collection()
{
people = new ArrayList<Person>();
min = 100;
max = 1;
total = 0;
}
BufferedReader fr = null;
BufferedWriter fw = null;
public void readFromFile() throws IOException
{
fr = new BufferedReader (new FileReader("people.txt"));
String line = null;
StringTokenizer st;
while (fr.ready())
{
line = fr.readLine();
st = new StringTokenizer(line);
String name = st.nextToken(";");
String surname = st.nextToken(";").toUpperCase();
String height = st.nextToken(";");
int age = Integer.parseInt(st.nextToken(";").trim());
Person p = new Person (name, surname, age);
p.toString();
people.add(p);
//for the 2nd part
if(age < min)
min = age;
if (age > max)
max = age;
total = total + age;
}
}
public int minAge()
{
int minA = 100;
for (int i = 0; i < people.size(); i++)
{
Person p = people.get(i);
int age = p.getAge();
if (age < minA)
{
minA = age;
}
}
System.out.print(minA+"; ");
return minA;
}
public int maxAge()
{
int maxA = 1;
for (int i = 0; i < people.size(); i++)
{
Person p = people.get(i);
int age = p.getAge();
if (age > maxA)
{
maxA = age;
}
}
System.out.print(maxA+"; ");
return maxA;
}
public float avgAge()
{
int sum = 0;
for (int i = 0; i < people.size(); i++)
{
Person p = people.get(i);
int age = p.getAge();
sum = sum + age;
}
float avgA = sum / people.size();
System.out.print(avgA);
return avgA;
}
public int fastMinAge()
{
//System.out.print("Minimum age: " + min);
return min;
}
public int fastMaxAge()
{
return max;
}
public float fastAvgAge()
{
return total / people.size();
}
public void writeToFile(String filename) throws IOException
{
StringBuffer val = new StringBuffer ("Minimum age: ");
val.append(fastMinAge());
val.append("\n Maximum age: ");
val.append(fastMaxAge());
val.append("\n Average age: ");
val.append(fastAvgAge());
BufferedWriter out = new BufferedWriter(new FileWriter(filename));
String outText = val.toString();
out.write(outText);
out.close();
}
public static void main(String[] args) throws IOException, ClassNotFoundException
{
Collection c = new Collection();
c.readFromFile();
for(Person d: people)
{
System.out.println(d);
}
c.minAge();
c.maxAge();
c.avgAge();
c.fastMinAge();
c.fastMaxAge();
c.fastAvgAge();
c.writeToFile("RESULTS.txt");
String filename = "people.txt";
//FileOutputStream fos = new FileOutputStream(filename);
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream(filename));
os.writeObject(c);
os.close();
String filename1 = "results1.txt";
FileInputStream fis = new FileInputStream(filename1);
ObjectInputStream ois = new ObjectInputStream(fis);
Collection p = (Collection) ois.readObject();
ois.close();
}
}
当我运行代码时，它会创建RESULTS.txt文件并在那里添加正确的信息。我确信代码的这一部分确实存在问题：
String filename = "people.txt";
//FileOutputStream fos = new FileOutputStream(filename);
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream(filename));
os.writeObject(c);
os.close();
String filename1 = "results1.txt";
FileInputStream fis = new FileInputStream(filename1);
ObjectInputStream ois = new ObjectInputStream(fis);
Collection p = (Collection) ois.readObject();
ois.close();
顺便说一句，我的people.txt文件变成了“¬ķ{sr java.io.NotSerializableException（Vxē†5 xrjava.io.ObjectStreamExceptiondĆäk¨9ūßxrjava.io.IOExceptionl€sde％š«xr java .lang.ExceptionŠż＆gt ;;Äxrjava.lang.ThrowableÕĘ5'9wøĖLcauset Ljava / lang / Throwable; L detailMessaget Ljava / lang / String; [ stackTracet [Ljava / lang / StackTraceElement; L suppressExceptionst Ljava / util / List; xpq~t SD3lab1.Collectionur [Ljava.lang.StackTraceElement; F *＆lt;＆lt;ż“9 xp srjava.lang.StackTraceElementaÅ＆amp;6Ż... I lineNumberL declaringClassq~L fileNameq~L methodNameq~xp˙˙˙˙tjava.io.ObjectOutputStreampt writeObject0sq~ ˙˙˙˙q~ptwriteObjectsq~ ©q~ t Collection.javat mainsr＆amp; java.util.Collections $UnmodifiableListü％1μLLlistq~xr，java.util.Collections $ UnmodifiableCollectionB€Ė^÷L ct Ljava / util / Collection; xpsrjava.util.ArrayListxŅ™Ēa¯I sizexp w xq~x“，我在控制台上收到这些错误：
Exception in thread "main" java.io.NotSerializableException: SD3lab1.Collection
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at SD3lab1.Collection.main(Collection.java:169)
非常感谢任何帮助
答案 0 :(得分：3)
您需要将Collection标记为Serializable
public class Collection implements Serializable {
此外，BufferedReader和BufferedWriter不可序列化，因此需要标记为transient
private transient BufferedReader fr;
private transient BufferedWriter fw;
同样使用诸如Collection之类的类名必然会引起混淆。考虑重命名该课程。