Not In query In Liferay Dynamic Query

In liferay dynamic query you can create a query for not in condition like
"SELECT * FROM traders WHERE traderId NOT IN(455,466)"


dynamicQuery.add(PropertyFactoryUtil.forName("primaryKey.traderId").notIn( StatutoryLocalServiceUtil.dynamicQuery() .add(PropertyFactoryUtil.forName("primaryKey.traderId").eq(455)) .add(PropertyFactoryUtil.forName("primaryKey.traderId").eq(456)) .setProjection(ProjectionFactoryUtil.property("primaryKey.traderId")) ));

Convert Amount In Words

A simple problem is to convert the given amount in words for receipt or other bills related usage.


import java.util.*; public class AmountInWords { private static String amount; private static int num; private static String[] units={""," One"," Two"," Three"," Four"," Five"," Six"," Seven"," Eight"," Nine"}; private static String[] teen={" Ten"," Eleven"," Twelve"," Thirteen"," Fourteen"," Fifteen"," Sixteen"," Seventeen"," Eighteen"," Nineteen"}; private static String[] tens={" Twenty"," Thirty"," Fourty"," Fifty"," Sixty"," Seventy"," Eighty"," Ninety"}; private static String[] maxs={"",""," Hundred"," Thousand"," Lakh"," Crore"}; public AmountInWords() { amount=""; } public String convertToWords(int n) { amount=numToString(n); String converted=""; int pos=1; boolean hun=false; while(amount.length()>0) { if(pos==1) // TENS AND UNIT POSITION { if(amount.length()>=2) // 2DIGIT NUMBERS { String C=amount.substring(amount.length()-2,amount.length()); amount=amount.substring(0,amount.length()-2); converted+=digits(C); } else if(amount.length()==1) // 1 DIGIT NUMBER { converted+=digits(amount); amount=""; } pos++; // INCREASING POSITION COUNTER } else if(pos==2) // HUNDRED POSITION { String C=amount.substring(amount.length()-1,amount.length()); amount=amount.substring(0,amount.length()-1); if(converted.length()>0&&digits(C)!=""){ converted=(digits(C)+maxs[pos]+" and")+converted;hun=true; } else{ if(digits(C)=="") ; else converted=(digits(C)+maxs[pos])+converted;hun=true;} pos++; // INCREASING POSITION COUNTER } else if(pos>2) // REMAINING NUMBERS PAIRED BY TWO { if(amount.length()>=2) // EXTRACT 2 DIGITS { String C=amount.substring(amount.length()-2,amount.length()); amount=amount.substring(0,amount.length()-2); if(!hun&&converted.length()>0)converted=digits(C)+maxs[pos]+" and"+converted; else{ if(digits(C)=="") ; else converted=digits(C)+maxs[pos]+converted; } } else if(amount.length()==1) // EXTRACT 1 DIGIT { if(!hun&&converted.length()>0)converted=digits(amount)+maxs[pos]+" and"+converted; else{ if(digits(amount)=="") ; else converted=digits(amount)+maxs[pos]+converted; amount=""; } } pos++; // INCREASING POSITION COUNTER } } return converted; } private String digits(String C) // TO RETURN SELECTED NUMBERS IN WORDS { String converted=""; for(int i=C.length()-1;i>=0;i--) { int ch=C.charAt(i)-48; if(i==0&&ch>1&&C.length()>1) converted=tens[ch-2]+converted; // IF TENS DIGIT STARTS WITH 2 OR MORE IT FALLS UNDER TENS else if(i==0&&ch==1&&C.length()==2) // IF TENS DIGIT STARTS WITH 1 IT FALLS UNDER TEENS { int sum=0; for(int j=0;j<2;j++) sum=(sum*10)+(C.charAt(j)-48); return teen[sum-10]; } else{ if(ch>0)converted=units[ch]+converted; } // IF SINGLE DIGIT PROVIDED } return converted; } private String numToString(int n) // CONVERT THE NUMBER TO STRING { String num=""; while(n!=0) { num=((char)((n%10)+48))+num; n/=10; } return num; } private void input() { Scanner in=new Scanner(System.in); try{System.out.print("Enter Amount to Convert in Words : "); num=in.nextInt();}catch(Exception e){System.out.println("Number Less than 1 Arab(1000000000) Only Possible.");System.exit(1);} } public static void main(String[] args) { AmountInWords obj=new AmountInWords(); obj.input(); System.out.println("Amount in Words : "+obj.convertToWords(num)); } }

Environment Variables In Java

Environment Variables  are variables that are added in any Operating system that can be accessed from anywhere in OS without using the complete(Real) location.

In a java Application System.getenv(); is used to find out the system environment variables

Example:-

import java.util.Map;

public class EnvMap {
    public static void main (String[] args) {
        Map<String, String> env = System.getenv();
        for (String envName : env.keySet()) {
            System.out.format("%s=%s%n",
                              envName,
                              env.get(envName));
        }
    }
}

The Security Manager

The security manager is an object that is used to check whether the operation we want to perform is not violating security policy of the operation system.
Sometime we want to perform any operation and got a exception

Exception in thread "AWT-EventQueue-1" java.security.AccessControlException: access denied (java.io.FilePermission characteroutput.txt write)
        at java.security.AccessControlContext.checkPermission(AccessControlContext.java:323)
        at java.security.AccessController.checkPermission(AccessController.java:546)
        at java.lang.SecurityManager.checkPermission(SecurityManager.java:532)
        at java.lang.SecurityManager.checkWrite(SecurityManager.java:962)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:169)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:70)
        at java.io.FileWriter.<init>(FileWriter.java:46)

...

To Prevent from this exception we can use SecurityManager class to check for the permission before performing operation.

The security manager is an object of type SecurityManager; to obtain a reference to this object, invoke System.getSecurityManager.

SecurityManager appsm = System.getSecurityManager();

If there is no security manager, this method returns null.

The SecurityManager class defines many other methods used to verify other kinds of operations. For example, SecurityManager.checkAccess verifies thread accesses, and SecurityManager.checkPropertyAccess verifies access to the specified property. Each operation or group of operations has its owncheckXXX() method.
In addition, the set of checkXXX() methods represents the set of operations that are already subject to the protection of the security manager. Typically, an application does not have to directly invoke any checkXXX() methods.

System Properties in java

There are various system properties that we need to use during our programs to perform some action or access some file.
There are some commonly used properties.

Key	Meaning
"file.separator"	Character that separates components of a file path. This is "/" on UNIX and "\" on Windows.
"java.class.path"	Path used to find directories and JAR archives containing class files. Elements of the class path are separated by a platform-specific character specified in the path.separator property.
"java.home"	Installation directory for Java Runtime Environment (JRE)
"java.vendor"	JRE vendor name
"java.vendor.url"	JRE vendor URL
"java.version"	JRE version number
"line.separator"	Sequence used by operating system to separate lines in text files
"os.arch"	Operating system architecture
"os.name"	Operating system name
"os.version"	Operating system version
"path.separator"	Path separator character used in java.class.path
"user.dir"	User working directory
"user.home"	User home directory
"user.name"	User account name

These are following keys that can be used to find out the property.
"System"  class has a properties Object associated with it that is used to find out those properties.

Example:-

strictfp Keyword in java

In java  strictfp   is used to strict all the calculations of  to strictly follow the strict floating point calculations in all platforms.

It can be used with class , interfaces and non-abstract methods. If used with the method then it ensures all the calculations inside that method must follow floating point math. When used with the class then it ensures all calculations inside that class must follow floating point math.

Compile-time constant expressions must always use strict floating-point behavior

It providestotal platform-independency and  take advantage of the speed and precision of the extended precision floating-point operations supported by x86 CPUs 

JAVA Standard Edition 5.0

JAVA 5.0 ( also known as Standard Edition 5.0 or J2SE 5 or J2SE 1.5) :-

Codename:- TIGER

1. Initially released in September 2004.

2. Has 3200+ classes and interfaces.

3. Introduced several updates and improvements

Annotations:- Anotations wrere used to provide meta-data for the programs so that it can be easily understand for metadata-aware programs.

Generics:-Generics are used to provide types of object belonging to collections. So that type safety cab be gauranteed at compile time.

Autoboxing :- Autoboxing is used to automatically convert from primitive types to wrapper clsses.

Improved syntax for looping :-Improved syntax of loops was introduced like for each loop

Varargs :- Provide flexibility to pass variable no of arguments.
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