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Java SecurityManager checkPackageDefinition() method with example

SecurityManager Class checkPackageDefinition() method: Here, we are going to learn about the checkPackageDefinition() method of SecurityManager Class with its syntax and example.
Submitted by Preeti Jain, on December 17, 2019

SecurityManager Class checkPackageDefinition() method

• checkPackageDefinition() method is available in java.lang package.
• We call getProperty("package.definition") to get a list of restricted packages and it checks when our pkg_name starts with or similar to any of the list of restricted packages and when it matches then it calls checkPermission with the RuntimePermission("defineClassInPackage."+pkg_name).
• checkPackageDefinition() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• checkPackageDefinition() method may throw an exception at the time of defining the class in the given package.
  SecurityException – This exception may throw when the calling thread does not have the right to define classes in the given package.

Syntax:

    public void checkPackageDefinition(String pkg_def);

Parameter(s):

• String pkg_def – represents the name of the package.

Return value:

The return type of this method is void, it returns nothing.

Example:

// Java program to demonstrate the example 
// of void checkPackageDefinition(String pkg_def)
// method of SecurityManager 

public class checkPackageDefinition extends SecurityManager {
    // override checkPackageDefinition() method of SecurityManager
    public void checkPackageDefinition(String pkg_def) {
        throw new SecurityException("Restricted...");
    }

    public static void main(String[] args) throws Exception {
        // By using setProperty() method is to set the policy property 
        // with security manager
        System.setProperty("java.security.policy", "file:/C:/java.policy");

        // Instantiating a checkPackageDefinition object
        checkPackageDefinition cpd = new checkPackageDefinition();

        // By using setSecurityManager() method is to set the
        // security manager
        System.setSecurityManager(cpd);

        // By using checkPackageDefinition(pkg_def) method is to check 
        // that package is defined or not
        cpd.checkPackageDefinition("java.lang");

        // Display the message
        System.out.println("Not Restricted..");
    }
}

Output

Exception in thread "main" java.lang.SecurityException: Restricted...
	at checkPackageDefinition.checkPackageDefinition(checkPackageDefinition.java:8)
	at checkPackageDefinition.main(checkPackageDefinition.java:25)