Runtime loadLibrary(String) in Java

loadLibrary(String): This method is available in the java.lang.Runtime class of Java.

Syntax:

void java.lang.Runtime.loadLibrary(String libname)

This method takes one argument. This method loads the native library specified by the libname argument.

The libname argument must not contain any platform-specific prefix, file extension, or path. If a native library called libname is statically linked with the VM, then the NI_OnLoad_libname function exported by the library is invoked.

Parameters: One parameter is required for this method.

libname: the name of the library.

Throws:

1. SecurityException - if a security manager exists and its checkLink method doesn't allow loading of the specified dynamic library.

2. UnsatisfiedLinkError - if either the libname argument contains a file path, the native library is not statically linked with the VM, or the library cannot be mapped to a native library image by the host system.

3. NullPointerException - if libname is null.

Approach 1: When no exception

Java

package com.Runtime;

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

        Runtime runtime = Runtime.getRuntime();

        String libname = "C:\\Windows\\System32\\AdvancedInstallers\\cmiv2.dll";
        runtime.loadLibrary(libname);
        System.out.println("Successfully loadLibrary");

    }
}

Output:

Successfully loadLibrary

Approach 2: UnsatisfiedLinkError

Java

package com.Runtime;

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

        Runtime runtime = Runtime.getRuntime();

        String libname = "C:\\Windows\\System32\\hello.dll";
        runtime.loadLibrary(libname);
        System.out.println("Successfully loadLibrary");

    }
}

Output:

Exception in thread "main" java.lang.UnsatisfiedLinkError: Directory separator should not appear in library name: C:\Windows\System32\hello.dll
	at java.base/java.lang.Runtime.loadLibrary0(Runtime.java:806)
	at java.base/java.lang.Runtime.loadLibrary(Runtime.java:797)
	at com.Runtime.RuntimeloadLibrary.main(RuntimeloadLibrary.java:9)

Approach 3: NullPointerException 

Java

package com.Runtime;

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

        Runtime runtime = Runtime.getRuntime();

        String libname = null;
        runtime.loadLibrary(libname);
        System.out.println("Successfully loadLibrary");

    }
}

Output:

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.indexOf(int)" because "libname" is null
	at java.base/java.lang.Runtime.loadLibrary0(Runtime.java:805)
	at java.base/java.lang.Runtime.loadLibrary(Runtime.java:797)
	at com.Runtime.RuntimeloadLibrary.main(RuntimeloadLibrary.java:9)

Some other methods of Runtime

addShutdownHook(Thread): This method registers a new virtual machine shutdown hook.

availableProcessors(): This method returns the number of processors available to the Java virtual machine.

exec(String): This method executes the specified string command in a separate process.

exec(String[]): This method executes the specified command and arguments in a separate process.

exec(String, String[]): This method executes the specified string command in a separate process with the specified environment.

exec(String[], String[]): This method executes the specified command and arguments in a separate process with the specified environment.

exec(String, String[], File): This method executes the specified string command in a separate process with the specified environment and working directory.

exec(String[], String[], File): This method executes the specified command and arguments in a separate process with the specified environment and working directory.

gc(): This method runs the garbage collector in the Java Virtual Machine.

Runtime.getRuntime(): This method returns the runtime object associated with the current Java application.

halt(int): This method forcibly terminates the currently running Java virtual machine.

load(String): This method loads the native library specified by the filename argument.

loadLibrary(String): This method loads the native library specified by the libname argument.

maxMemory(): This method returns the maximum amount of memory that the Java virtual machine will attempt to use.

removeShutdownHook(Thread): This method De-registers a previously registered virtual machine shutdown hook.

runFinalization(): This method runs the finalization methods of any objects pending finalization.

version(): This method returns the version of the Java Runtime Environment as a Version.

exit(int): This method terminates the currently running Java virtual machine by initiating its shutdown sequence. This method never returns normally.

freeMemory(): This method returns the amount of free memory in the Java Virtual Machine.

totalMemory(): This method returns the total amount of memory in the Java virtual machine.