3.9 Java I/O system 3.9.1 Questions: 1. Which of the next statements are true: a. The File class is used for random access to binary files b. To list all the file with java extension in a directory, a FilenameFilter class has to be provided as parameter to the list() method of the File class c. A File object can represent both a file and directory d. Using the File class is possible to look at the characteristics of files 2. Which is the base class of decorators for classes having as base class the InputStream? 3. What is the main difference between PrintStream and DataOutputStream classes? 4. Is it possible to do random access file using InputStream classes? 5. Check the next code snippet for correctness: // 1. Reading input by lines: BufferedReader in = newBufferedReader( newFileInpuStream("IOStreamDemo.java")); String s, s2 = new String(); while((s = in.readLine())!= null) s2 += s + "\n"; in.close ); 6. Which class is used to add a new file to a zip archive? 7. How the serialization of a class can be customized in order to avoid the default serialization? 8. What is the difference in the construction of a Serializable and an Externalizable object during de serialization? 9. What is weird in the next class: public class Account implements Externalizable public void writeExternal(ObjectOutput out) throwsIOException public void readExternal(ObjectInput in) throwsIOException, ClassNotFoundException } 10. With which kind of objects is working the StreamTokenizer class? 3.9.2 Problems 1. Create a code to open a text file and read the file one line at a time. 2. Create an externalizable class called Account which contains an id and a password, the password is not serialized. 3. Write a program that compares the performance of writing the lines to a file when using buffered and unbuffered I/O both for writer and output stream classes. 4. Write in a file 4 integers and then reread the third and fourth ones using random access to the file. 5. Read an arbitrary file, compress it to another file and display the compression ratio.
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