這個課程的參考視頻和圖片來自youtube。

? ? 主要學到的知識點有：

We want to handle the bad Error. (e.g bad input / bugs in program)

1. File() : A Java representation of a file.

File file = new File("test.txt");

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2.?PrintWriter()?: Write to a file.?

• Write string into the file.?

// Write 2 lines(Johnson, 26) into the test.txt file. (If not exist then create one, otherwise will overwrite it.) PrintWriter output = new PrintWriter(file); output.println("Johnson"); output.println("26"); output.close();

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3.?Scanner()?: Read from a file.?

• Read string from the file.?

Scanner input = new Scanner(file); String name = input.nextLine(); int age = input.nextLine();

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4. Object Serialization : convert an object into a series of bytes so they can be written to disk?

• Serialization: Object to Disk
• Deserialization: Disk to Object
• In order to use the seialization, we need to add implement Serializable in the class definition (the contens will be in a binary format)

public class Student implements Serializable {

• FileInputStream & ObjectInputStream

　　? ? ?Read from a file as bytes and deserialize a data input stream back into an object

// deserialize the collection of students FileinputStream fi = new FileinputSream(file); ObjectInputStream input = new ObjectOutputStream(fi); while(input.hasNext()){Student s =(Student) input.readObject();students.add(s); } input.close();// Important when writing a file as operating system will deny other programs access until the file is closed fi.close();

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• FileOutputStream & ObjectOutputStream

　　? ? ?Write to a file as bytes and serialize an object?into?a data input stream

// serialize the collection of students FileOutputStream fo = new FileOutputSream(file); ObjectOutputStream output = new ObjectOutputStream(fo); for(Student s: students){output.writeObject(s); } output.close();// Important when writing a file as operating system will deny other programs access until the file is closed fo.close();

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轉載于:https://www.cnblogs.com/Johnsonxiong/p/10204160.html

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