-3
我想从.dat文件中检索多个hashmaps 但是它只给我第一个存储！反序列化HashMap dosent给我所有的元素
public class TestSerialize
{
public static void main(String args[]) throws IOException
{
HashMap<String, String> students = new HashMap<String, String>();
// This part I changed everytime to keep the data stored in "students.dat"
// I want to retrieve all the keys that have been run
students.put("22", "xxx");
students.put("33", "yyy");
ObjectOutputStream out = new ObjectOutputStream(
new FileOutputStream("students.dat", true));
out.writeObject(students);
out.close();
}
}
下面的代码是用来反序列化
public class TestSerialize2
{
public static void main(String args[]) throws IOException, ClassNotFoundException
{
ObjectInputStream in = new ObjectInputStream(
new FileInputStream("students.dat"));
HashMap<String, String> students = new HashMap<String, String>();
students = (HashMap<String, String>) in.readObject();
in.close();
for (String s : students.keySet())
System.out.println(s);
}
}
我希望这是明确的..
（在万阿英，蒋达清出现运行（TestSerialize类惠荫）第二次与提供不同的密钥学生..（TestSerialize2类）的输出将是旧的值只有22,33）希望这是帮助
在您的意见我试试这个： 但同样的问题仍然存在！
package week8;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.HashMap;
public class TestSerialize
{
\t public static void main(String args[]) throws IOException, ClassNotFoundException
\t {
\t \t HashMap<String, String> students = new HashMap<String, String>();
\t \t // This part I changed everytime to keep the data stored in "students.dat"
\t \t // I want to retrieve all the keys that have been run
\t \t students.put("66", "xxx");
\t \t students.put("99", "yyy");
\t \t ObjectOutputStream out = new ObjectOutputStream(
\t \t \t \t new FileOutputStream("students.dat", true));
\t \t File file = new File("students.dat");
\t \t if (file.length() == 0){
\t \t \t System.out.print("sss");
\t \t \t out.writeObject(students);
\t \t \t out.close();
\t \t }else
\t \t {
\t \t \t students =readThenWrite(students);
\t \t \t for (String s : students.keySet())
\t System.out.println(s);
\t \t \t
\t \t \t out.writeObject(students);
\t \t \t out.close();
\t \t \t
\t \t \t
\t
\t \t }
\t }
\t private static HashMap<String, String> readThenWrite(HashMap<String, String> students) {
HashMap<String, String> ss = new HashMap<String, String>();
ObjectInputStream in;
\t \t try {
\t \t \t in = new ObjectInputStream(
\t \t \t new FileInputStream("students.dat"));
\t \t
\t \t ss = (HashMap<String, String>) in.readObject();
\t \t
\t \t in.close();
\t \t for (String s : students.keySet())
\t \t ss.put(s, students.get(s));
\t \t
\t \t
\t \t
\t \t
\t \t } catch (IOException | ClassNotFoundException e) {
\t \t \t e.printStackTrace();
\t \t }
\t \t
\t \t return ss;
\t }
}
适用于我（Linux，Java 8）。 – Robert
您提供的代码无法在我们的机器上重现问题。你能重现吗？你真的只是使用这个代码？在保存之前，也许你还有其他一些类操作你的设置...因为除了代码中的一些缺陷之外，它看起来是正确的。 – Zabuza
完美的作品 –