Book是自定义类型,本来想从文件读入list类型放到静态变量 list 中,但是不知道为什么不能运行,Book没有改动,txt现在是空的,不能运行
```java
import java.io.File;
import java.io.FileInputStream;
import java.io.ObjectInputStream;
import java.util.ArrayList;
public class Test {
static ArrayList<Book> l = new ArrayList<Book>();
public static void main(String[] args) throws Exception {
readObject();
}
public static void readObject() throws Exception {
ObjectInputStream in = null;
FileInputStream fin = null;
File file = new File("src/test.txt");
if(file.exists()) {
fin = new FileInputStream(file);
in = new ObjectInputStream(fin);
l = (ArrayList<Book>) in.readObject();
}else {
file.createNewFile();
}
fin.close();
in.close();
}
}
```