SecurityManager checkAccess(Thread) in Java

checkAccess(Thread): This method is available in the java.lang.SecurityManager class of Java.

Syntax:

void java.lang.SecurityManager.checkAccess(Thread t)

This method takes one argument. This method throws a SecurityException if the calling thread is not allowed to modify the thread argument.

Parameters: One parameter is required for this method.

t: the thread to be checked.

Returns: NA

Throws:

1. SecurityException - if the calling thread does not have permission to modify the thread.

2. NullPointerException - if the thread argument is null.

Approach 1: When no exception

Java

package com.SecurityManager;

public class SecurityManagercheckAccess {
    public static void main(String[] args) {

        SecurityManager securityManager = new SecurityManager();

        Thread t = new Thread();
        securityManager.checkAccess(t);
        System.out.println("Successfully check the access");
    }
}

Output:

Successfully check the access

Approach 2: NullPointerException 

Java

package com.SecurityManager;

public class SecurityManagercheckAccess {
    public static void main(String[] args) {

        SecurityManager securityManager = new SecurityManager();

        Thread t = null;
        securityManager.checkAccess(t);
        System.out.println("Successfully check the access");
    }
}

Output:

Exception in thread "main" java.lang.NullPointerException: thread can't be null
	at java.base/java.lang.SecurityManager.checkAccess(SecurityManager.java:532)
	at com.SecurityManager.SecurityManagercheckAccess.main(SecurityManagercheckAccess.java:9)

Some other methods of SecurityManager

SecurityManager(): This method constructs a new SecurityManager.

checkAccept(String, int): This method throws a SecurityException if the calling thread is not permitted to accept a socket connection from the specified host and port number.

checkAccess(Thread): This method throws a SecurityException if the calling thread is not allowed to modify the thread argument.

checkAccess(ThreadGroup): This method throws a SecurityException if the calling thread is not allowed to modify the thread group argument.

checkConnect(String, int): This method throws a SecurityException if the calling thread is not allowed to open a socket connection to the specified host and port number.

checkConnect(String, int, Object): This method throws a SecurityException if the specified security context is not allowed to open a socket connection to the specified host and port number.

checkCreateClassLoader(): This method throws a SecurityException if the calling thread is not allowed to create a new class loader.

checkDelete(String): This method throws a SecurityException if the calling thread is not allowed to delete the specified file.

checkExec(String): This method throws a SecurityException if the calling thread is not allowed to create a subprocess.

checkExit(int): This method throws a SecurityException if the calling thread is not allowed to cause the Java Virtual Machine to halt with the specified status code.

checkLink(String): This method throws a SecurityException if the calling thread is not allowed to dynamic link the library code specified by the string argument file.

checkListen(int): This method throws a SecurityException if the calling thread is not allowed to wait for a connection request on the specified local port number.

checkMulticast(InetAddress): This method throws a SecurityException if the calling thread is not allowed to use(join/leave/send/receive) IP multicast.

checkPackageAccess(String): This method throws a SecurityException if the calling thread is not allowed to access the specified package.

checkPackageDefinition(String): This method throws a SecurityException if the calling thread is not allowed to define classes in the specified package.

checkPermission(Permission): This method throws a SecurityException if the requested access, specified by the given permission, is not permitted based on the security policy currently in effect.

checkPermission(Permission, Object): This method throws a SecurityException if the specified security context is denied access to the resource specified by the given permission.

checkPrintJobAccess(): This method throws a SecurityException if the calling thread is not allowed to initiate a print job request.

checkPropertiesAccess(): This method throws a SecurityException if the calling thread is not allowed to access or modify the system properties.

checkPropertyAccess(String): This method throws a SecurityException if the calling thread is not allowed to access the system property with the specified key name.

checkRead(FileDescriptor): This method throws a SecurityException if the calling thread is not allowed to read from the specified file descriptor.

checkRead(String): This method throws a SecurityException if the calling thread is not allowed to read the file specified by the string argument.

checkRead(String, Object): This method throws a SecurityException if the specified security context is not allowed to read the file specified by the string argument.

checkSecurityAccess(String): This method determines whether permission with the specified target name should be granted or denied.

checkSetFactory(): This method throws a SecurityException if the calling thread is not allowed to set the socket factory used by ServerSocket or Socket or the stream handler factory used by URL.

checkWrite(FileDescriptor):  This method throws a SecurityException if the calling thread is not allowed to write to the specified file descriptor.

checkWrite(String): This method throws a SecurityException if the calling thread is not allowed to write to the file specified by the string argument.

getSecurityContext(): This method creates an object that encapsulates the current execution environment.

getThreadGroup(): This method returns the thread group into which to instantiate any new thread being created at the time this is being called.