24 Bytes: 2012

Sample program in java for Deadlock

package concurrency;
public class DeadLock {
    public static void main(String[] args) {
        JavaFile firstFile = new JavaFile("file1");
        JavaFile secondFile = new JavaFile("file2");
        JavaCoder firstCode = new JavaCoder(firstFile, secondFile, "first coder:");
        JavaCoder secondCoder = new JavaCoder(secondFile, firstFile, "second coder:");
        firstCode.start();
        secondCoder.start();
    }
}
class JavaCoder extends Thread {
    public void run() {
        System.out.println(Thread.currentThread().getName() + "trying to checkin " + firstfile);
        this.firstfile.checkIn(this.secondfile);
    }
    private JavaFile secondfile;
    private JavaFile firstfile;
    JavaCoder(JavaFile firstFile, JavaFile secondFile, String name) {
        super(name);
        this.firstfile = firstFile;
        this.secondfile = secondFile;
    }
};
class JavaFile {
    private String name;
    JavaFile(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return this.name;
    }
    public synchronized void checkIn(JavaFile otherFile) {
        System.out.println(Thread.currentThread().getName() + "in check-in " + this);
        otherFile.checkOut();
        System.out.println(Thread.currentThread().getName() + "completing check-in " + this);
    }
    public synchronized void checkOut() {
        System.out.println(Thread.currentThread().getName() + "in check-out " + this);
        while (true) {
        }
    }
};
 
Sample Output
first coder:trying to checkin file1
first coder:in check-in file1
first coder:in check-out file2
second coder:trying to checkin file2 ( This is the dead lock , second coder is trying to checkin file 2 which is locked by first coder for check-out)

Stop a thread in java

static boolean stopRequested = false;
    public static synchronized boolean isStopped() {
        return stopRequested;
    }
    public static synchronized void stopRequested() {
        StopThread.stopRequested = true;
    }
    public static void main(String ar[]) throws InterruptedException {
        Thread runningThread = new Thread(new Runnable() {
            @Override
            public void run() {
                while (!isStopped()) {
                    System.out.println(stopRequested);
                }
            }
        });
        runningThread.start();
        System.out.println("Stop Running Thread");
        stopRequested();
    }

Effective JUNIT's

PIT

http://pitest.org/ best place to start

Mutations supported and The details of each type of mutation are here

http://pitest.org/quickstart/mutators/

not all are enabled by default (please check I am not sure)

How to use with Maven

1) Add the plugin

org.pitest

pitest-maven

LATEST

x.x.somepackage.*

2) Execute the command mvn org.pitest:pitest-maven:mutationCoverage

3) Check the report in \target\pit-reports

Sonar:

Sonar has a plugin for pit tests which adds these survived mutations as violations

Eclipse :

To install pit for eclipse refer

Java Object Class

it is the base class of all the classes in java

Methods in Java Object class

hashCode:
- the more unique the hashCode is the more efficient is the hash map/table
- used to find the bucket in which an object goes into in a hash table.
- more than one invocation of hashCode of the same object should return same Integer.
- if two objects are equal according to equals method then their hashCode must be same.
equals:
- is used in hashMap when two objects have same hashCode.
- if two objects are equal their hashCode must be same.
- it should be
  - reflexive : x.equals(x)
  - symmetric: x.equals(y) and y.equals(x)
  - transtive: x.equals(y) y.equals(z) implies => x.equals(z)
  - consitent: x.equals(y) should allways return same value.
  - for null it should be false: x.equals(null) false
- the default behaviour of equals = “==” i.e is object comparision
toString :
- the default implementation is
- classname @ hex format of the hashCode.
- its good to override toString .
- also should be concise and informative.
clone:
- to clone the object .
- x.clone() != x
- x.clone().getClass() == x.getClass() Not mandatory *
- x.clone().equals(x) Not mandatory *
- alternative to clone is copy constructor

Must have Eclipse Plugins

m2eclipse: maven plugin for eclipse
PIT Mutation Test: this plugin helps run mutation tests in eclipse
Sonar plugin for eclipse: run sonar analysis locally or remotely.
Jupiter Plugin:Code Review
TDD Plugins

infinitest: runs junit infinetlyhttp://infinitest.github.com/user_guide.html : run related junits for every change
Static Code Analsis: PMD Programmer Mistakes detector and FindBugs for eclipse
JUNIT Coverage : EclEmma/clover
JUNIT junit helper, quick unit

Creating jdbc data source on weblogic using java code

1:

   2:  import java.net.UnknownHostException;

3:

   4:  import org.python.util.InteractiveInterpreter;

5:

   6:  import weblogic.management.scripting.utils.WLSTInterpreter;

7:

   8:  public class DataSourceCreator {

9:

  10:      static InteractiveInterpreter interpreter = null;

  11:      private String weblogicPassword;

  12:      private String weblogicUserName;

  13:      private StringBuffer wlst_script;

14:

  15:      public DataSourceCreator(String weblogicUserName, String weblogicPassword) {

  16:          interpreter = new WLSTInterpreter();

  17:          this.weblogicUserName = weblogicUserName;

  18:          this.weblogicPassword = weblogicPassword;

19:

  20:      }

21:

  22:      /**

  23:       * connect to weblogic

  24:       */

  25:      private void connect() {

  26:          wlst_script.append("connect('" + this.weblogicUserName + "','" + this.weblogicPassword

  27:                  + "')");

  28:      }

29:

  30:      /**

  31:       * creates the data source script

  32:       *

  33:       * @param dbpassword

  34:       * @param dbuser

  35:       * @param dsname

  36:       * @param jndiname

  37:       * @param dburi

  38:       * @param dbdrivername

  39:       */

  40:      private void createDataSourceScript(String dbpassword, String dbuser, String dsname,

  41:              String jndiname, String dburi, String dbdrivername) {

42:

  43:          int timeout = 100000;

  44:          int maxcapacity = 100;

45:

  46:          // substitute your server name here "SERVER_NAME" i.e the target.

  47:          wlst_script.append("cd('Servers/SERVER_NAME')\n");

  48:          wlst_script.append("target=cmo\n");

  49:          wlst_script.append("cd('../..')\n");

  50:          wlst_script.append("jdbcSystemResource = create('" + dsname + "','JDBCSystemResource')\n");

  51:          wlst_script.append("theJDBCResource = jdbcSystemResource.getJDBCResource()\n");

  52:          wlst_script.append("theJDBCResource.setName('" + dsname + "')\n");

  53:          wlst_script

  54:                  .append("connectionPoolParams = theJDBCResource.getJDBCConnectionPoolParams()\n");

  55:          wlst_script.append("connectionPoolParams.setConnectionReserveTimeoutSeconds(int('"

  56:                  + timeout + "'))\n");

57:

  58:          // maximum connections that can be made

  59:          wlst_script.append("connectionPoolParams.setMaxCapacity(int('" + maxcapacity + "'))\n");

  60:          // query to execute using ds to test if its successfull

  61:          wlst_script.append("connectionPoolParams.setTestTableName('SQL SELECT 1 FROM DUAL')\n");

62:

  63:          // update data source params

  64:          wlst_script.append("dsParams = theJDBCResource.getJDBCDataSourceParams()\n");

  65:          wlst_script.append("dsParams.addJNDIName('" + jndiname + "')\n");

66:

  67:          wlst_script.append("driverParams = theJDBCResource.getJDBCDriverParams()\n");

  68:          wlst_script.append("driverParams.setUrl('" + dburi + "')\n");

  69:          wlst_script.append("driverParams.setDriverName('" + dbdrivername + "')\n");

  70:          wlst_script.append("driverParams.setPassword('" + dbpassword + "')\n");

71:

  72:          wlst_script.append("driverProperties = driverParams.getProperties()\n");

  73:          wlst_script.append("proper = driverProperties.createProperty('user')\n");

  74:          wlst_script.append("proper.setValue('" + dbuser + "')\n");

  75:          wlst_script.append("proper1 = driverProperties.createProperty('DatabaseName')\n");

  76:          wlst_script.append("proper1.setValue('" + dburi + "')\n");

  77:          wlst_script.append("jdbcSystemResource.addTarget(target)\n");

  78:      }

79:

  80:      /**

  81:       * @param wlst_script

  82:       */

  83:      private void saveActivateAndDisconnect() {

  84:          // save , activate changes and disconnect

  85:          wlst_script.append("save()\n");

  86:          wlst_script.append("activate(block='true')\n");

  87:          wlst_script.append("disconnect()\n");

  88:      }

89:

  90:      /**

  91:       * start edit

  92:       *

  93:       * @param wlst_script

  94:       */

  95:      private void startEdit() {

  96:          wlst_script.append("edit()\n");

  97:          wlst_script.append("startEdit()\n");

  98:      }

99:

 100:      public static void main(String args[]) throws UnknownHostException {

 101:

 102:          // weblogic related

 103:          String weblogicUserName = "username";

 104:          String weblogicPassword = "password";

 105:

 106:          DataSourceCreator dsCreator = new DataSourceCreator(weblogicUserName, weblogicPassword);

 107:

 108:          dsCreator.connect();

 109:          dsCreator.startEdit();

 110:          String sid = "sidofdb"; // sid of db

 111:          String ipaddress = "10.8.11.16"; // ip addres

 112:          String dbpassword = "password"; // database password

 113:          String dbuser = "username"; // db user name

 114:          String dsname = "datasourcename"; // your data source name

 115:          String jndiname = "jdbc/" + dsname; // jndi name for ds

 116:          String dburi = "jdbc:oracle:thin:@" + ipaddress + ":1521:" + sid;

 117:          String dbdrivername = "oracle.jdbc.driver.OracleDriver";

 118:

 119:          dsCreator.createDataSourceScript(dbpassword, dbuser, dsname, jndiname, dburi, dbdrivername);

 120:          dsCreator.saveActivateAndDisconnect();

 121:

 122:          try {

 123:              // execute the script created above

 124:              interpreter.exec(dsCreator.wlst_script.toString());

 125:          } finally {

 126:              // disconnect even if there is exception

 127:              interpreter.exec("disconnect()\n");

 128:          }

 129:

 130:      }

 131:

 132:  }

\Java\jre6\lib\ext\QTJava.zip was unexpected at this time.

just check if "Java\jre6\lib\ext\QTJava.zip" is there in the class path you just have to remove and restart weblogic.

Map mapping = new HashMap();

   Conversion() {
       mapping.put("I", 1);
       mapping.put("V", 5);
       mapping.put("X", 10);
       mapping.put("L", 50);
       mapping.put("C", 100);
       mapping.put("D", 500);
       mapping.put("M", 1000);

   }

   /**
   * @param romanNumber
   * @return
   */
   public int romanToDecimal(String romanNumber) {
       int result = 0;

       if (romanNumber.length() == 0) {
           return result;
       }

       if (romanNumber.length() == 1) {
           return (Integer) mapping.get(romanNumber);
       }

       else {
           int leftEnd = (Integer) mapping.get(romanNumber.charAt(0) + "");

           if (leftEnd >= (Integer) mapping.get(romanNumber.charAt(1) + "")) {

               result += leftEnd;
           } else {
               result += - leftEnd;
           }
           result += romanToDecimal(romanNumber.substring(1));
       }
       return result;
   }

Invoke a webservice from linux shell

ENDPOINT="http://localhost:8001/soa-infra/services/default/App/StartApp"

curl --silent --data @- --header 'Content-Type: application/soap+xml; charset=utf-8' --user-agent "" ${ENDPOINT} <<EOF  
<?xml version="1.0" encoding="utf-8"?>
<soap12:Envelope    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xmlns:xsd="http://www.w3.org/2001/XMLSchema"    xmlns:soap12="http://www.w3.org/2003/05/soap-envelope"  xmlns:ns1="http://xmlns.oracle.com/Application/StartApp">
<soap12:Body>
<ns1:process>                        
<ns1:input>running</ns1:input>        
</ns1:process>    
</soap12:Body> 
</soap12:Envelope>
EOF

ENDPOINT : this can be configured to point to ws endpoint

The envelope in weblogic can be got by clicking test on the web service and switching to xml view.

Curl is a command line tool to transfer data to a URL

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