How to construct a queue data structure using stacks

Stacks and queues.

  
Each is defined by two basic operations: insert a new item, and remove an item. When we insert an item, our intent is clear. But when we remove an item, which one do we choose? The rule used for a queue is to always remove the item that has been in the collection the mostamount of time. This policy is known as first-in-first-out or FIFO. The rule used for a stack is to always remove the item that has been in the collection the least amount of time. This policy is known as last-in first-out or LIFO.


construct a queue data structure using only the Single stacks


public class SimulatedQueue<E> { 
    private java.util.Stack<E> stack = new java.util.Stack<E>(); 

    public void insert(E elem) { 
        if (!stack.empty()) { 
            E topElem = stack.pop(); 
            insert(elem); 
            stack.push(topElem); 
        } 
        else 
            stack.push(elem); 
    } 

    public E remove() { 
        return stack.pop(); 
    } 
}

construct a queue data structure using only the two stacks


public class Queue<E> 
{ 

    private Stack<E> inbox = new Stack<E>(); 
    private Stack<E> outbox = new Stack<E>(); 

    public void queue(E item) { 
        inbox.push(item); 
    } 

    public E dequeue() { 
        if (outbox.isEmpty()) { 
            while (!inbox.isEmpty()) { 
               outbox.push(inbox.pop()); 
            } 
        } 
        return outbox.pop(); 
    } 

}

Extjs 4.x Tips and Tricks

I will try to add few points  based on my experience in extjs 4.x.

• Communication between different controller.(use fireEvent on application)

this.fireEvent('expand', this, cmp, e);

• Lazy initialization of controller.

someAction: function() {
    var controller = this.getController('AnotherController');
 
    // Remember to call the init method manually
    controller.init();
}

• Avoid "Id" in coding for reusable component

Don't put id to components, Add id to where it use in your code 

{
  xtype:'customercombo',
  id:'cust-project-field-cust-name'
}

• Avoid using Ext.getCmp()..use Ext.ComponentQuery  
• Minimize no of panel in application.
• Avoid using ownerCt proprety
• Reduce container nesting
• Reduce border layout nesting
• Try to reuse the code
• Make a cleaner separation between model,view and controller

Only put static code in view and event code in controller and model to store the data

• Replace Panels with Containers

Panel is more expensive than contaier. Declare   xtype: 'container'  to avoid default panel.

{
 xtype: 'container', // defaultType is 'panel'
 items: [ ... ]
}

Ant task to deploy ear file to weblogic server from IDE(Jdeveloper/Eclipse).

Please find steps to deploy ear file weblogic server from IDE.

• Changes in build.properties file.

    weblogic Deployment properties - Modify as per your weblogic environment

• weblgoic.deployer.uri=t3://localhost:7001
• weblogic.admin.user=weblogic
• weblogic.admin.password=welcome1
• weblogic.server=SWserver

• Changes in build.xml file.

• <property environment="env"/>
  <target name="deploy-weblogic" depends="dist">
  
  <taskdef name="wldeploy"
  
          classname="weblogic.ant.taskdefs.management.WLDeploy">
  
    <classpath> 
  
    <pathelement location="${env.WL_HOME}\server\lib\weblogic.jar"/> 
  
    </classpath>
  
  
  </taskdef>
  <wldeploy action="deploy" verbose="true" debug="true"
  
  name="${ear.deployment.name}" source="${deploy.dir}/${ear.file}"
  
  user="${weblogic.admin.user}" password="${weblogic.admin.password}"
  
  adminurl="${weblgoic.deployer.uri}" targets="${weblogic.server}"  />
  
  
  </target>
  
  
  

How to set up DB2 datasource in weblogic server 11g

Before you create datasource in weblogic server you need to follow few steps .

Get the following jar files

• db2java.zip
• db2jcc.jar
• db2jcc_javax.jar
• db2jcc_license_cisuz.jar
• db2jcc_license_cu.jar
• db2cc_javax.jar

change the setDomainEnv.cmd. file with below changes.

set DB2_DRIVER=../sqllib/java/db2java.zip;../sqllib/java/db2jcc.jar;../sqllib/java/db2jcc_javax.jar;.../sqllib/java/db2jcc_license_cisuz.jar;../sqllib/java/db2jcc_license_cu.jar;../sqllib/java/db2cc_javax.jar;

set CLASSPATH=%CLASSPATH%;%DB2_DRIVER%

How to pass extra parameter to extjs combo

I have to one scenario, Suppose there are two combo ,I need to pass first one value as parameter of second combo query param.

Let say i have two combos in form

items:[

{

 fieldLabel: 'Customer Name',

 xtype:'customerlovcombo',

 width:550,

 id:'form-field-custproj-cust-name'

},

{

 fieldLabel: 'Project Name',

 xtype:'projectlovcombo',

 width:550,

 id:'form-field-custproj-proj-name'

}

]

Here i want to pass customerId as part of  proejctlovcombo.
What we need to do is in controller user beforequery to pass extra param as part of  proejctlovcombo

init: function() {
    '#form-field-custproj-proj-name':{
    beforequery:this.formatQuery
    }
},

formatQuery: function(queryEvent) {
var custName = Ext.getCmp('form-filed-cust-name').getRawValue();
 if(custName !=null && custName != ""){
  queryEvent.combo.getStore().getProxy().extraParams.custName=custName;
  }
}

How to change grid column header name in extjs

Suppose I have below grid. I want to change header 2 to  "Inst" from "Instance".

    var grid = new Ext.grid.GridPanel({
        store: store,
        columns: [new Ext.grid.RowNumberer({width: 30}),
            {header: "Date", width: 50, dataIndex: 'timestamp', sortable: true},
            {header: "Instance", width: 120, dataIndex: 'olt', sortable: true},
            {header: "DL", width: 50, dataIndex: 'dl', sortable: true}
        ], ...

In extjs 3.x :

   Use the code like this
  grid.getColumnModel().setColumnHeader(2,'Inst');

In extjs 4.x :

   Use the code like this.
   grid.columns[1].setText('Inst');