Create a New File if it not exitst and write content into file

import java.io.*;

public class WriteIntoFile {

public static void main(String args[]) throws IOException{

File f =new File("log.txt");

if(!f.exists())
f.createNewFile();
System.out.println(f.getAbsolutePath());

FileOutputStream fout = new FileOutputStream(f);
fout.write("Writing into file".getBytes());

fout.flush();
fout.close();

System.out.println("success");
}
}

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Reading from file and writing into Console output

import java.io.*;

public class ReadingFromFile {

public static void main(String args[]) throws IOException{

FileInputStream in = new FileInputStream("log.txt");

int c;
while((c=in.read())!=-1){
System.out.print((char)c);
}

}

}

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Write and Read from File using FileInputStream & FileOutputStream

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Scanner;

public class ReadingWriting {

public static void main(String args[]) throws IOException{

Scanner sc = new Scanner(System.in);
System.out.print("enter input: ");
String str= sc.nextLine();
System.out.println(str);

FileOutputStream fout=new FileOutputStream("Output.txt");
//System.out.println(str.getBytes());

fout.write(str.getBytes());

fout.flush();
fout.close();

FileInputStream fin=new FileInputStream("Output.txt");
int c;
while((c=fin.read())!=-1){
System.out.print((char)c);
}

fin.close();
}
}

//enter input: a b c
//a b c
//9732983299 output byte
// System.out.print((char)c); output chars

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Reading & Writing into files using FileReader and FileWriter

import java.util.Scanner;
import java.io.*;
public class FileReaderWriter {

public static void main(String args[]) throws IOException{

Scanner sc = new Scanner(System.in);

System.out.print("enter input: ");
String str = sc.nextLine();

FileWriter fout = new FileWriter("fout.txt");

fout.write(str);

fout.flush();
fout.close();

int c;

FileReader fin = new FileReader("fout.txt");

while((c=fin.read())!=-1){
System.out.print((char)c);
}

fin.close();
}
}

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InputStream & OutputStream

import java.io.*;

public class InputOutputStream {

public static void main(String args[]) throws IOException{

OutputStream out=new FileOutputStream("file.txt");

byte bArr[]={65,32,66,32,67};

for(int i=0;i<bArr.length;i++){
out.write(bArr[i]);
}
out.flush();
out.close();

InputStream in = new FileInputStream("file.txt");

int size=in.available();
System.out.println(size);

for(int j=0;j<size;j++){
System.out.print((char)in.read());
}

in.close();

}

}

// 5

// A B C

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Create a new Directory

package com.files;

import java.io.*;
public class CreateDirectory {

public static void main(String args[]){

String dirname ="Z:/Java/Files/tmp";
File f = new File(dirname);

boolean check;
check=f.mkdir();
System.out.println(check); // return true if directory is created
}
}
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List Directories

import java.io.*;

public class ListDirectories {

public static void main(String args[]){

File file =null;
String[] paths;

file =new File("Z:/Java/Files");

paths=file.list();

for(String path:paths){
System.out.println(path);
}
}
}

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http://tutorials.jenkov.com
Notes

FileInputStream & FileOutputStream

- Both are Byte Stream

- Reads and writes 8 bits at a time

- FileOutputStream can be used create a new file if not exist

- File f =new File("log.txt"); It won't create a new file

FileReader & FileWriter

- Both are character streams

- Reads and writes 16 bit unicode

- Reads and writes 2 Bytes at a time

- Internally uses FileInputStream and FileOutputStream

- FileWriter can be used to create a new file if not exist

FileInputStream

This stream is used for reading data from the files. Objects can be created using the keyword new and there are several types of constructors available.

Following constructor takes a file name as a string to create an input stream object to read the file −

InputStream f = new FileInputStream("C:/java/hello");

Following constructor takes a file object to create an input stream object to read the file. First we create a file object using File() method as follows −

File f = new File("C:/java/hello");
InputStream f = new FileInputStream(f);

Once you have InputStream object in hand, then there is a list of helper methods which can be used to read to stream or to do other operations on the stream.

FileOutputStream

FileOutputStream is used to create a file and write data into it. The stream would create a file, if it doesn't already exist, before opening it for output.

Here are two constructors which can be used to create a FileOutputStream object.

Following constructor takes a file name as a string to create an input stream object to write the file −

OutputStream f = new FileOutputStream("C:/java/hello")

Following constructor takes a file object to create an output stream object to write the file. First, we create a file object using File() method as follows −

File f = new File("C:/java/hello");
OutputStream f = new FileOutputStream(f);

Once you have OutputStream object in hand, then there is a list of helper methods, which can be used to write to stream or to do other operations on the stream.

How to Migrate a Jenkins Job to New Jenkins Server

JAN 26TH 2015 (COMMENTS)

We recently setup a new Jenkins build server for some iOS applications and I wanted to find a quick way to copy a couple Jobs from the old server to the new one.

Below are a few small options I found while working on the task.

Option 1: Copy `jobs` directory

One option (and seems to be the recommended one) is to just copy the jobs directory from the old server to the new one.

From the documentation Moving/copying/renaming jobs:

You can:

Move a job from one installation of Jenkins to another by simply copying the corresponding job directory.

Make a copy of an existing job by making a clone of a job directory by a different name.

Rename an existing job by renaming a directory. Note that the if you change a job name you will need to change any other job that tries to call the renamed job.

Those operations can be done even when Jenkins is running. For changes like these to take effect, you have to click "reload config" to force Jenkins to reload configuration from the disk.

For me, I skipped this option because I was having a hard time finding where the jobs directory was on the old server. (Or just too lazy to find it, and I only had a couple jobs to copy over)

Option 2: Try one of the plugins out there

There are some Jenkins plugins out there that provide some job export options. Here are a couple...

~~Job Exporter Plugin~~ Thanks to a comment below for pointing out this doesn't actually export jobs - but environment variables when the task runs...
Job Importer Plugin

Option 3: Use Jenkins CLI

This is what I used, which worked nicely for only the few jobs we had. If you have a large number of Jenkins jobs, you may consider the first aproach above.

First download the Jenkins CLI jar.

You can do this from your jenkin's CLI page within your installed Jenkins instance.

Next we can use the following command (pointing to the old server) to list the jobs.

java -jar jenkins-cli.jar -s http://<YourBuildServer>:<YourBuildServerPort>/ list-jobs

Using one job from the list above, let's copy the xml of a job to the clipboard. (I'm using a Mac which is were pbcopy & pbpastecome from below)

java -jar jenkins-cli.jar -s http://<YourBuildServer>:<YourBuildServerPort>/ get-job "NAME_OF_JOB" | pbcopy

This uses the cli get-job "NAME_OF_JOB" command to print the job's xml to stdout, which we pipe to pbcopy on the Mac to load the configuration into the clipboard. You could of course pipe the output to a file like ... > job.xml