Think in java Stream 經典

stream
import java.io.*;

public class NewIODemo {public static void main(String[] args) { try {   // 1. Reading input by lines:   BufferedReader in =   new BufferedReader(   new FileReader(args[0]));   String s, s2 = new String();   while((s = in.readLine())!= null)   s2 += s + "\n";   in.close();    // 1b. Reading standard input:   BufferedReader stdin =    new BufferedReader(     new InputStreamReader(System.in));    System.out.print("Enter a line:");   System.out.println(stdin.readLine());      // 2. Input from memory   StringReader in2 = new StringReader(s2);   int c;   while((c = in2.read()) != -1)    System.out.print((char)c);      // 3. Formatted memory input   try {     DataInputStream in3 =     new DataInputStream(     // Oops: must use deprecated class:     new StringBufferInputStream(s2));     while(true)      System.out.print((char)in3.readByte());   } catch(EOFException e) {      System.out.println("End of stream");   }      // 4. Line numbering & file output   try {     LineNumberReader li =      new LineNumberReader(       new StringReader(s2));     BufferedReader in4 =      new BufferedReader(li);     PrintWriter out1 =      new PrintWriter(       new BufferedWriter(        new FileWriter("IODemo.out")));     while((s = in4.readLine()) != null )     out1.println(      "Line " + li.getLineNumber() + s);     out1.close();   } catch(EOFException e) {     System.out.println("End of stream");   }      // 5. Storing & recovering data   try {     DataOutputStream out2 =     new DataOutputStream(       new BufferedOutputStream(         new FileOutputStream("Data.txt")));     out2.writeDouble(3.14159);     out2.writeBytes("That was pi");     out2.close();     DataInputStream in5 =     new DataInputStream(      new BufferedInputStream(       new FileInputStream("Data.txt")));     BufferedReader in5br =       new BufferedReader(         new InputStreamReader(in5));     // Must use DataInputStream for data:     System.out.println(in5.readDouble());     // Can now use the "proper" readLine():     System.out.println(in5br.readLine());   } catch(EOFException e) {     System.out.println("End of stream");   }      // 6. Reading and writing random access   // files is the same as before.   // (not repeated here)      } catch(FileNotFoundException e) {     System.out.println(     "File Not Found:" + args[1]);   } catch(IOException e) {     System.out.println("IO Exception");   } }} ///:~