Java将对象输入流读入arraylist？
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Java read object input stream into arraylist?
提问by ash
The method below is supposed to read a binary file into an arrayList. But getting a java.io.EOFException:
下面的方法应该将二进制文件读入arrayList. 但是得到一个java.io.EOFException：
at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2553) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1296) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350) at .... Read(Tester.java:400) at .... main(Tester.java:23)
Line 23 at main just calls the method, line 400 is the while loop below. Any ideas?
main 的第 23 行只是调用了该方法，第 400 行是下面的 while 循环。有任何想法吗？
private static void Read() {
try {
ObjectInputStream objIn = new ObjectInputStream(new FileInputStream("/file.bin"));
while (objIn.readObject() != null) {
list.add((Libreria) objIn.readObject());
}
objIn.close();
} catch(Exception e) {
e.printStackTrace();
}
}
回答by Vincent Ramdhanie
The problem is that you are calling readObject() twice in the loop. Try this instead:
问题是您在循环中两次调用 readObject() 。试试这个：
MediaLibrary obj = null;
while ((obj = (MediaLibrary)objIn.readObject()) != null) {
libraryFromDisk.add(obj);
}
回答by Jihed Amine
You're reading an object in the while test:
您正在 while 测试中读取一个对象：
while (objIn.readObject() != null)
Then you're reading the next object in:
然后你正在阅读下一个对象：
libraryFromDisk.add((MediaLibrary) objIn.readObject());
So in one iteration you should read only one object
所以在一次迭代中你应该只读取一个对象
private static void Load() {
try {
ObjectInputStream objIn = new ObjectInputStream(new FileInputStream("/file.bin"));
Object object = objIn.readObject();
while (object != null) {
libraryFromDisk.add((MediaLibrary) object);
object = objIn.readObject();
}
objIn.close();
} catch(Exception e) {
e.printStackTrace();
}
}
回答by user207421
As per the other answers you are reading twice in the loop. Your other problem is the null test. readObject()only returns null if you have written a null, not at EOS, so there's not much point in using it as a loop termination test. The correct termination of a readObject()loop is
根据其他答案，您在循环中阅读了两次。您的另一个问题是空测试。readObject()如果您写了空值，则仅返回空值，而不是在 EOS 上，因此将其用作循环终止测试没有多大意义。readObject()循环的正确终止是
catch (EOFException exc)
{
in.close();
break;
}
回答by duyetpt
You can try this. Good luck!
你可以试试这个。祝你好运！
private static void Load() {
try {
ObjectInputStream objIn = new ObjectInputStream(new FileInputStream("/file.bin"));
boolean check=true;
while (check) {
try{
object = objIn.readObject();
libraryFromDisk.add((MediaLibrary) object);
}catch(EOFException ex){
check=false;
}
}
objIn.close();
} catch(Exception e) {
e.printStackTrace();
}
}
