ADF : Working with ViewCriteria

View Criteria's are additional where clause added at runtime to base View Object Query.


 Programmer can create view criteria declaratively or programatically.

1. Create View Criteria Declaratively Open View Object in Edit and in "Query" tab you can click "+" add pencil to create new view criteria

 
2. Control View Criteria Programatically.

 a- Get View Criteria from View Criteria manager within View Object and then apply it  
ViewCriteria applyVC = myViewObject.getViewCriteria("MyViewCriteriaName");
myViewObject.applyViewCriteria(applyVC);
myViewObject.executeQuery();
b- Applying Multiple view Criteria's
 
When multiple view criteria's are applied to the view object, the view criterias gets appended or replaced depending upon the way you use applyViewCriteria API
Replacing Existing view criteria's :
 
myViewObject.applyViewCriteria(applyVC) or
myViewObject.applyViewCriteria(applyVC,false)
will erase all previously applied view criterias and apply the current view criteria only.
Appending to the Existing view criteria:

myViewObject.applyViewCriteria(applyVC, true) 
 Will append this view criteria to the existing view criteria(s) which is applied already.

c- Unapplying && Removing View Criteria

vo.removeApplyViewCriteriaName()
Unapply the view criteria if it is applied. The view criteria will still remain in View Criteria Manager (which means you can't apply this view criteria whenever you require in the future).
vo.removeViewCriteria()
Removes the view criteria from View Criteria Manager. If it is applied it is first unapplied and then removed. (which means you cant apply this View Criteria to the view object next time in the future.).

For example the below code returns null after removeViewCriteria has been applied.
ViewCriteria applyVC = myViewObject.getViewCriteria("MyViewCriteriaName")

vo.clearViewCriterias()
Unapplies and removes all view criteria, both applied and unapplied from View Criteria Manager. Which means that you can't apply any View Criteria against View Object.
For example the below code returns null after clearViewCriterias() has been applied.
ViewCriteria applyVC = myViewObject.getViewCriteria("MyViewCriteriaName")
myViewObject.applyViewCriteria(null)
The above statement unapplies all existing View Criterias and not remove it.

myViewObject.setNamedWhereClauseParam("MyParameter", "myValue)

The above statement set Named Parameter Value. It set the value of "MyParameter" to "myValue".

I post in previous post about  ADF : Change View Criteria Columns at Runtime

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Random Numbers in Java

Previously I posted  about Generate Random Passwords in Oracle that was using PLSQL.
Today I will post about java randoms.

Java provides two classes to generate random numbers: Random and SecureRandom.
Random is faster than SecureRandom, but it uses a 48 bits seeds which is not enough for the long type.
Moreover, it is not 'random enough' for cryptography. SecureRandom, is slower than Random, but can be used for cryptography.

The following code example shows how to generate a random number within a range for int, long, float and double.

Note rangeStart , rangeEnd is range period of generated numbers .

        int rangeStart = 50;
        int rangeEnd = 100;

        SecureRandom secRandom = new SecureRandom();
        int inclusive = rangeEnd - rangeStart + 1;
        int exclusive = rangeEnd - rangeStart;


        int randomIntInclusive = secRandom.nextInt(inclusive) + rangeStart;
        int randomIntExclusive = secRandom.nextInt(exclusive) + rangeStart;

        System.out.println("randomIntInclusive : " + randomIntInclusive);
        System.out.println("randomIntExclusive : " + randomIntExclusive);

        long randomLongInclusive =
            (secRandom.nextLong() % inclusive) + rangeStart;
        long randomLongExclusive =
            (secRandom.nextLong() % exclusive) + rangeStart;

        System.out.println("randomLongInclusive : " + randomLongInclusive);
        System.out.println("randomLongExclusive : " + randomLongExclusive);

        float randomFloat = (secRandom.nextFloat() * exclusive) + rangeStart;
        System.out.println("randomFloat : " + randomFloat);

        double randomDouble =
            (secRandom.nextDouble() * exclusive) + rangeStart;
        System.out.println("randomDouble : " + randomDouble);

The output will be
randomIntInclusive : 60
randomIntExclusive : 73
randomLongInclusive : 11
randomLongExclusive : 63
randomFloat : 65.19333
randomDouble : 84.14220368726888


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Close Resources in Java

In java when using any resources like Files, Streams, Database Connection and DataSets etc .... , you must close resources at end of processing at your code.

For Example : Streams 

        File f = new File("myFile.txt");
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(f);
            // Do something...
        } catch (FileNotFoundException ex) {
            // Display error message
        } finally {
            // Closing resource
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException ex) {
                    //Here , Hide Exception
                }
            }
        }

All previous code in Blue color are used to close resources.
So to save time and make code more readability you can use IOUtils Appache packages  to close resources quietly

      finally{
   IOUtils.closeQuietly(fos);
      }



For Example : Database Statement

 finally{
   DBTransaction txn = this.getDBTransaction();
        String sqlStmt =
            "Begin plsqlCode; END;";
        CallableStatement callStmt =
            txn.createCallableStatement(sqlStmt, DBTransaction.DEFAULT);
        try {
             //Write your code here to work with CallableStatement 
        } catch (SQLException e) {
             //Handle SQL Exception
        }finally {
            // Closing resource
            if (callStmt != null) {
                try {
                    callStmt .close();
                } catch (SQLException ex) {
                    //Here , Hide Exception
                }
            }
        }

All previous code in Blue color are used to close resources.
So to save time and make code more readability you can use DBUtils Appache packages  to close resources quietly

      finally{
   DbUtils.closeQuietly(callStmt );
      }

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Run JavaScript from Native Java

I wrote in previous post Execute Javascript code from Java Code how to execute java script in Oracle ADF.
But in this post I will explain how to call Javascript from native Java.



The following code snippets will illustrate how to evaluate Javascript code and invoke functions and get return value.

import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class CallJavaScript {
    public static void callJsCode(String jsCode) throws ScriptException,
                                                        NoSuchMethodException {

        // Retrieving the Javascript engine
        ScriptEngine se =
            new ScriptEngineManager().getEngineByName("javascript");
        try {
            se.eval(jsCode);
        } catch (ScriptException e) {
            e.printStackTrace();
        }

        try {
            Invocable jsinvoke = (Invocable)se;
            System.out.println("myFunction(2) returns: " +
                               jsinvoke.invokeFunction("myFunction", 2, 4));
        } catch (ScriptException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }

    }
}

Then You can call this code using for example

       try {
            String jsCode =
                "function myFunction(x,y){return x+y;}";
            CallJavaScript.callJsCode(jsCode);
        } catch (ScriptException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }      

The output of previous code will be

myFunction(2) returns: 6.0

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Iterate Through Java Map

There are multiple ways to iterate through a Java Map.

Assuming the following map declaration:
Map mapObj = new HashMap();

//Use Iterator [Generic]
Iterator> iter= mapObj.entrySet().iterator();
while ( iter.hasNext() ) {
    Entry item = iterator.next();
    System.out.println(item.getKey() + " - " + item.getValue());
}

//User Iterator [Without Generic]
Iterator iter= mapObj.entrySet().iterator();
while ( iterator2.hasNext() ) {
    Entry item = (Entry) iterator.next();
    System.out.println(item.getKey() + " - " + item.getValue());
}

// Use For Each [Generic]
for ( Entry item : mapObj.entrySet() ) {
    System.out.println(item.getKey()+ " - " + item.getValue());
}

// Use For Each [Without Generic]
for ( Entry item : mapObj.entrySet() ) {
    System.out.println(item.getKey()+ " - " + item.getValue());
}

//Fetch Value using Key
for ( String key : mapObj.keySet() ) {
    System.out.println(key + " - " + mapObj.get(key));
}


// Loop through Keys only
for ( String key : mapObj.keySet() ) {
    System.out.println(key);
}


// Loop through Values only
for ( Object value : mapObj.values() ) {
    System.out.println(value);
}

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ADF : Change View Criteria Columns at Runtime

When creating view criteria related to view object, then all querable attributes are displayed in view criteria by default.
So I want to change the properties of this attributes at run time pragmatically to display or hide specific attributes in view criteria.

I developed the following method for this purpose, You can add this method to ViewObjectImpl class.

I pass attribute name and a Boolean value to determine display in view criteria or no.

 public void setQuerable(String attributeName, Boolean isQuerable) {  
   
     int indx = this.getAttributeIndexOf(attributeName);  
   
     ViewAttributeDefImpl attr = (ViewAttributeDefImpl)this.getAttributeDef(indx);  
   
     attr.setQueriable(isQuerable);  
   
   }  

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Uncommitted data warning

If you are working entry data page and some feilds has been changed and you moved to another page, data still in cache but not posted or commited.

So to show warning of unsaved data before moving to another page you can do this by setting "Uncommitted data warning" property of af:document to "true". Then whenever user change data and  move out of current page or close the browser, it will display a warning of unsaved data

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