What is PATH and CLASSPATH in Java - Path vs ClassPath | Java67
On the other hand CLASSPATH environment variable is used by System or Application ClassLoader to locate and load compile Java bytecodes stored in .class file.
2) In order to set PATH in Java you need to include JDK_HOME/bin directory in PATH environment variable while in order to set CLASSPATH in Java you need to include all those directory where you have put either your .class file or JAR file which is required by your Java application.
3) Another significant difference between PATH and CLASSPATH is that PATH can not be overridden by any Java settings but CLASSPATH can be overridden by providing command line option -classpath or -cp to both "java" and "javac" commands or by using Class-Path attribute in Manifest file inside JAR archive.
4) PATH environment variable is used by operating system to find any binary or command typed in shell, this is true for both Windows and Linux environment while CLASSPATH is only used by Java ClassLoaders to load class files.
We usually set PATH as environment variable, set classpath when start java application.
export CLASSPATH= ${CLASSPATH}:/opt/Java/JDK1.6.18/lib
Also don't forget to include current directory, denoted by dot(.) to include in CLASSPATH, this will ensure that it will look first on current directory and if it found the class it will use that even if that class also exists in another directory which exists in CLASSPATH.
http://javarevisited.blogspot.sg/2011/01/how-classpath-work-in-java.html
Classpath in Java is path to directory or list of directory which is used by ClassLoaders to find and load class in Java program. Classpath can be specified using CLASSPATH environment variable which is case insensitive, -cp or -classpathcommand line option or Class-Path attribute inmanifest.mf file inside JAR file in Java.
Key thing to note is that presence of that class on Java classpath is not checked on compile time. So even if those classes are not present on Java classpath your program will compile successfully and only fail when you try to run.
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Difference between PATH and CLASSPATH in Java
1)Main difference between PATH and CLASSPATH is that PATH is an environment variable which is used to locate JDK binaries like "java" or "javac" command used to run java program and compile java source file.On the other hand CLASSPATH environment variable is used by System or Application ClassLoader to locate and load compile Java bytecodes stored in .class file.
2) In order to set PATH in Java you need to include JDK_HOME/bin directory in PATH environment variable while in order to set CLASSPATH in Java you need to include all those directory where you have put either your .class file or JAR file which is required by your Java application.
3) Another significant difference between PATH and CLASSPATH is that PATH can not be overridden by any Java settings but CLASSPATH can be overridden by providing command line option -classpath or -cp to both "java" and "javac" commands or by using Class-Path attribute in Manifest file inside JAR archive.
4) PATH environment variable is used by operating system to find any binary or command typed in shell, this is true for both Windows and Linux environment while CLASSPATH is only used by Java ClassLoaders to load class files.
We usually set PATH as environment variable, set classpath when start java application.
export CLASSPATH= ${CLASSPATH}:/opt/Java/JDK1.6.18/lib
Also don't forget to include current directory, denoted by dot(.) to include in CLASSPATH, this will ensure that it will look first on current directory and if it found the class it will use that even if that class also exists in another directory which exists in CLASSPATH.
http://javarevisited.blogspot.sg/2011/01/how-classpath-work-in-java.html
Classpath in Java is path to directory or list of directory which is used by ClassLoaders to find and load class in Java program. Classpath can be specified using CLASSPATH environment variable which is case insensitive, -cp or -classpathcommand line option or Class-Path attribute inmanifest.mf file inside JAR file in Java.
3. If two classes with same name exist in Java Classpath then the class which comes earlier in Classpath will be picked by Java Virtual Machine.
4. By default CLASSPATH in Java points to current directory denoted by "." and it will look for any class only in current directory.
5. When you use the -jar command line option to run your program as an executable JAR, then the Java CLASSPATH environment variable will be ignored, and also the -cp and -classpath switches will be ignored and In this case you can set your java classpath in the META-INF/MANIFEST.MF file by using the Class-Path attribute.
9. ClassNotFoundException is an Exception and will be thrown when Java program dynamically tries to load a particular Class at Runtime and don’t find that on Java classpath due to result of Class.forName() or loadClass() method invocation.
Key thing to note is that presence of that class on Java classpath is not checked on compile time. So even if those classes are not present on Java classpath your program will compile successfully and only fail when you try to run.
10. NoClassDefFoundError comes when a particular class was present in Java Classpath during compile time but not available during runtime on Classpath in Java.
NoClassDefFoundError is an Error and more critical thanClassNotFoundException which is an exception and recoverable.
