Tutorial by Examples: classpath

public class UnsafeLoader { public static Unsafe loadUnsafe() { return Unsafe.getUnsafe(); } } While this example will compile, it is likely to fail at runtime unless the Unsafe class was loaded with the primary classloader. To ensure that happens the JVM should be loaded with...

There are three ways to set the classpath. It can be set using the CLASSPATH environment variable : set CLASSPATH=... # Windows and csh export CLASSPATH=... # Unix ksh/bash It can be set on the command line as follows java -classpath ... javac -classpath ... Note ...

If you want to add all the JARs in directory to the classpath, you can do this concisely using classpath wildcard syntax; for example: someFolder/* This tells the JVM to add all JAR and ZIP files in the someFolder directory to the classpath. This syntax can be used in a -cp argument, a CLASSPA...

The classpath is a sequence of entries which are directory pathnames, JAR or ZIP file pathnames, or JAR / ZIP wildcard specifications. For a classpath specified on the command line (e.g. -classpath) or as an environment variable, the entries must be separated with ; (semicolon) characters on Wi...

Sometimes, just adding all the JARs from a folder isn't enough, for example when you have native code and need to select a subset of JARs. In this case, you need two main() methods. The first one builds a classloader and then uses this classloader to call the second main(). Here is an example which...

It can be useful to load a resource (image, text file, properties, KeyStore, ...) that is packaged inside a JAR. For this purpose, we can use the Class and ClassLoaders. Suppose we have the following project structure : program.jar | \-com \-project | |-file.txt \-Test.class ...

The purpose of the classpath is to tell a JVM where to find classes and other resources. The meaning of the classpath and the search process are intertwined. The classpath is a form of search path which specifies a sequence of locations to look for resources. In a standard classpath, these places...

The normal Java classloaders look for classes first in the bootstrap classpath, before checking for extensions and the application classpath. By default, the bootstrap classpath consists of the "rt.jar" file and some other important JAR files that are supplied by the JRE installation. Th...