Java Programming Idea--I/O system __ algorithm

1,file class

Represents the name of a particular file and the name of a group of files under a directory. If it points to a set of files, you can call the list () method with the collection of words and return an array of characters.

Example 1

Package filetest;

Import Java.io.File;

public class Dirlist {

	/**
	 * @param args */public
	static void Main (string[] args) {
		//TODO Auto-gene Rated method stub
		file Filedir=new file ("/home/hadoop/data/lucenedata");
		File[] Textfiles=filedir.listfiles ();
		for (File file:textfiles) {
			System.out.println (File.getabsolutepath ());
			System.out.println (File.getname ());}}

Results

/home/hadoop/data/lucenedata/txt1.txt
txt1.txt
/home/hadoop/data/lucenedata/txt2.txt
txt2.txt
/home/hadoop/data/lucenedata/txt5.txt
txt5.txt
/home/hadoop/data/lucenedata/txt4.txt
Txt4.txt
/home/hadoop/data/lucenedata/txt3.txt
txt3.txt

Absolute path and filename of output file

2, input and output

Buffer input File

Package inoutput;

Import Java.io.BufferedReader;
Import Java.io.FileReader;
Import Java.io.IOError;
Import java.io.IOException;

public class Bufferedinputfile {

	/**
	 * @param args
	 *
	/public static String read (String filename) throws I oexception{
		BufferedReader in=new bufferedreader (new FileReader (filename));
		String s;
		StringBuilder SB =new StringBuilder ();
		while ((S=in.readline ())!=null) {
			sb.append (s+ "\ n");
		}
		In.close ();
		return sb.tostring ();
	}
	public static void Main (string[] args) throws IOException {
		//TODO auto-generated method stub
		System.out.print ln (Read ("./src/filetest/dirlist.java"));
	}

Results

Package filetest;

Import Java.io.File;
Import java.io.IOException;

public class Dirlist {

	/**
	 * @param args
	 * @throws ioexception
	/public static void Main (string[) AR GS) throws IOException {
		//TODO auto-generated method stub
		File Filedir=new file ("/home/hadoop/data/lucenedata ");
		File[] Textfiles=filedir.listfiles ();
		for (File file:textfiles) {
			System.out.println (File.getabsolutepath ());
			System.out.println (File.getcanonicalpath ());
			System.out.println (File.getname ());}}

Input from memory

Package inoutput;

Import java.io.IOException;
Import Java.io.StringReader;

public class Memoryinput {

	/**
	 * @param args
	 * @throws ioexception
	/public static void main (String [] args) throws IOException {
		//TODO auto-generated method stub
		StringReader inreader=new StringReader ( Bufferedinputfile.read ("./src/filetest/dirlist.java"));
		int C;
		while ((C=inreader.read ())!=-1) {
			System.out.println ((char) c);
		}
		System.out.println (Bufferedinputfile.read ("./src/filetest/dirlist.java"));
	}

Results

Package inoutput;

Import java.io.IOException;
Import Java.io.StringReader;

public class Memoryinput {

	/**
	 * @param args
	 * @throws ioexception
	/public static void main (String [] args) throws IOException {
		//TODO auto-generated method stub
		StringReader inreader=new StringReader ( Bufferedinputfile.read ("./src/filetest/dirlist.java"));
		int C;
		while ((C=inreader.read ())!=-1) {
			System.out.println ((char) c);
		}
		System.out.println (Bufferedinputfile.read ("./src/filetest/dirlist.java"));
	}

Basic file output

Package inoutput;

Import Java.io.BufferedReader;
Import Java.io.FileReader;
Import java.io.IOException;
Import Java.io.PrintWriter;
Import Java.io.StringReader;

public class Basicfileoutput {
	static String file = ' output.out ';
	/**
	 * @param args */public
	static void Main (string[] args) throws ioexception{
		//TODO auto-generated Method stub
		BufferedReader in= new BufferedReader (Bufferedinputfile.read ("./src/filetest/ Dirlist.java "));
		PrintWriter out=new printwriter (file);
		int linecount=1;
		String s;
		while ((S=in.readline ())!=null) {
			out.println (linecount++ + ":" +s);
		}
		Out.close ();
		System.out.println (bufferedinputfile.read (file));//Read System.out.println from memory
		(Bufferedinputfile.read ("./ Output.out "));
	}

Results

1:package filetest;
2:3: Import java.io.File;
4:import java.io.IOException;  5:6: public class Dirlist {7:8:/** 9: * @param args: * @throws ioexception One: * * 12:public static void Main (string[] args) throws IOException {://TODO auto-generated method stub 14:file filedir=new File ("/home/hado
Op/data/lucenedata ");
15:file[] Textfiles=filedir.listfiles (); 16:for (File file:textfiles) {17:system.out.println (File.getabsolutepath ()); 18:system.out.println (File.getCano
Nicalpath ());
19:system.out.println (File.getname ());
21:22:} 23:24:} 1:package filetest;
2:3: Import java.io.File;
4:import java.io.IOException;  5:6: public class Dirlist {7:8:/** 9: * @param args: * @throws ioexception One: * * 12:public static void Main (string[] args) throws IOException {://TODO auto-generated method stub 14:file filedir=new File ("/home/hado
Op/data/lucenedata ");
15:file[] Textfiles=filedir.listfiles (); 		16:for (File file:textfiles) {17:system.out.println (File.getabsolutepath ()); 18:system.out.println (File.getCanonicalP
Ath ());
19:system.out.println (File.getname ()); 20:} 21:22:} 23:24:}

3,i/o

Read from standard input

Package IO;

Import Java.io.BufferedReader;
Import java.io.IOException;
Import Java.io.InputStreamReader;

public class Echo {

	/**
	 * @param args
	 * @throws ioexception
	/public static void Main (string[) args) Throws IOException {
		//TODO auto-generated method stub
		bufferedreader stdin =new bufferedreader (New Inputstrea Mreader (system.in));
		String s;
		while ((S=stdin.readline ())!= null && s.length ()!=0) {
			System.out.println (s);
		}
	}

}

Results

haha
haha

Output

Package IO;

Import Java.io.PrintWriter;

public class Changesystemout {

	/**
	 * @param args */public
	static void Main (string[] args) {
		//TODO A uto-generated method Stub
		printwriter out =new printwriter (system.out,true);
		Out.println ("hello,world!");
	}

Results

hello,world!