How To Choke Surroundings Variables Inward Java- Representative Tutorial
Wednesday, August 15, 2018
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Environment variables inwards Java
There are ii ways to larn surround variable inwards Java, past times using System properties or past times using System.getEnv(). System properties provides alone express prepare of predefined surround variables similar java.classpath, for retrieving Java Classpath or java.username to larn User Id which is used to run Java programme etc but a to a greater extent than robust in addition to platform independent means of getting surround variable inwards Java program on the other manus System.getEnv() method render access to all surround variables within Java programme but discipline to innovate platform dependency if programme relies on a item surround variable. System.getEnv() is overloaded method inwards Java API in addition to if invoked without parameter it returns an unmodifiable String map which contains all surround variables in addition to at that topographic point values available to this Java procedure piece System.getEnv(String name) returns value of surround variable if exists or null. In our before posts nosotros convey seen How to larn electrical current directory inwards Java in addition to How to run rhythm ascendency from Java program in addition to inwards this Java tutorial nosotros volition encounter how to access surround variable inwards Java.
How to larn surround variables inwards Java - Example
String map of all surround variables piece System.getEnv(String name) only render value of named surround variable similar JAVA_HOME volition render PATH of your JDK installation directory.
/**
* Java programme to demonstrate How to larn value of surround variables inwards Java.
* Don't confuse betwixt System belongings in addition to Environment variable in addition to at that topographic point is separate
* means to larn value of System belongings than surround variable inwards Java, equally shown inwards this
* example.
*
* @author Javin Paul
*/
public class EnvironmentVariableDemo {
public static void main(String args[]){
//getting username using System.getProperty inwards Java
String user = System.getProperty("user.name") ;
System.out.println("Username using organisation property: " + user);
//getting username equally surround variable inwards java, alone plant inwards windows
String userWindows = System.getenv("USERNAME");
System.out.println("Username using surround variable inwards windows : " + userWindows);
//name in addition to value of all surround variable inwards Java program
Map<String, String> env = System.getenv();
for (String envName : env.keySet()) {
System.out.format("%s=%s%n", envName, env.get(envName));
}
}
}
Output:
Username using organisation property: harry
Username using surround variable inwards windows : harry
USERPROFILE=C:\Documents in addition to Settings\harry
JAVA_HOME=C:\Program Files\Java\jdk1.6.0_20\
TEMP=C:\DOCUME 1\harry\LOCALS 1\Temp
* Java programme to demonstrate How to larn value of surround variables inwards Java.
* Don't confuse betwixt System belongings in addition to Environment variable in addition to at that topographic point is separate
* means to larn value of System belongings than surround variable inwards Java, equally shown inwards this
* example.
*
* @author Javin Paul
*/
public class EnvironmentVariableDemo {
public static void main(String args[]){
//getting username using System.getProperty inwards Java
String user = System.getProperty("user.name") ;
System.out.println("Username using organisation property: " + user);
//getting username equally surround variable inwards java, alone plant inwards windows
String userWindows = System.getenv("USERNAME");
System.out.println("Username using surround variable inwards windows : " + userWindows);
//name in addition to value of all surround variable inwards Java program
Map<String, String> env = System.getenv();
for (String envName : env.keySet()) {
System.out.format("%s=%s%n", envName, env.get(envName));
}
}
}
Output:
Username using organisation property: harry
Username using surround variable inwards windows : harry
USERPROFILE=C:\Documents in addition to Settings\harry
JAVA_HOME=C:\Program Files\Java\jdk1.6.0_20\
TEMP=C:\DOCUME 1\harry\LOCALS 1\Temp
Getting surround variable inwards Java – Things to remember
Java is platform independent linguistic communication but at that topographic point are many things which tin make a Java programme platform dependent e.g. using a native library. Since surround variables likewise vary from ane platform to around other e.g. from windows to Unix y'all ask to live on fleck careful piece straight accessing surround variable within Java program. Here are few points which is worth noting :
1) Use organisation properties if value of surround variable is available via system property e.g. Username which is available using "user.name" organisation property. If y'all access it using surround variable straight y'all may ask to inquire for dissimilar variable equally it may live on dissimilar inwards Windows e.g. USERNAME in addition to Unix equally USER.
2) Environment variables are case sensitive inwards Unix piece instance insensitive inwards Windows in addition to thus relying on that tin ane time to a greater extent than brand your Java programme platform dependent.
3) System.getEnv() was deprecated inwards unloosen JDK 1.3 inwards back upwards of using System.getProperty() but reinstated ane time to a greater extent than inwards JDK 1.5.
That's all on how to larn surround variable inwards Java. Though y'all convey convenient method similar System.getEnv() which tin render value of surround variable, its amend to purpose System.getProperty() to larn that value inwards a platform independent way, if that surround variable is available equally organisation belongings inwards Java.
Further Learning
Complete Java Masterclass
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