Find the common java commands list along with some examples. Study a short description and use cases. Learn how to use the java command properly when programming.
javac [ options ] [ sourcefiles ]
This javac command example and its options read an assortment of Java class and interface definitions coded in the Java programming language. It then compiles them into bytecode and relevant class files. Additionally, the javac tool can also create annotations in an array of Java source files and classes.
javap [options] classes...
The javap command is responsible for disassembling one or more class files. The out is dependent on the options used. When there is no option used, the javap command prints both the protected and public fields, and all the methods of the classes that are passed on to it.
rmic [ options ] package-qualified-class-name
You can use rmic compiler command to seamlessly create stub and skeleton class files using the Java Remote Method Protocol9 (JRMP) and automatically stub and tie all class files (IIOP protocol) for the remote protocol. The rmic compiler is the best tool for generating Object Management Group (OMG) Interface Definition Language (IDL)
klist [ [-c] [-f] [-e] [-a [-n]] ] [-k [-t] [-K] ] [name] [-help]]
The klist command is used to display all entries in the local credentials cache and key table. The klist command enables the programmer to view entries in the local credentials cache and key table. The klist tool cannot be used to change the Kerberos database. It’s only used to verify the contents of the credentials cache or keytab.
jarsigner [ options ] [jar-file alias} jarsigner -verify [ options ] jar-file [alias ...]
The jarsigner command plays two major purposes.
policytool [ -file ] [ filename ]
You can use the policy tool command to read and write all plain text policy files regarding the user input through the utility GUI. The policy tool command calls an administrator’s GUI that helps the system administrator to manage the policy information of local policy files.
keytool [commands]
Java key tool commands act as a key and certificate management utility. It helps end user to administer his or her own private/public key pairs and associated certificates that are used in self-authentication (where users are allowed to authenticate themselves to other users and services)
jshell [options] [load-files]
You use jshell command when you want to interactively evaluate statements and declarations written in Java Programming Language in a read-eval-print loop (REPL)
jdeprscan [ options ]{dir|jar|class}
You use the jdeprscan basic Java commands as a special static analysis tool that is used to scan a jar file (or an array of aggregation of class files) for the application of deprecated API elements. Jdeprscan tool is provided by JDK to scan files that are defined by Java SE. Other deprecated APIs from third-party libraries aren’t reported.
jdeps [options] path ...
You can use jdeps command when launching the java class dependency analyzer. This java command syntax shows either the package-level or class level dependency of the Java class files.
jmod (create|extract|list|describe|hash) [options] jmod-file
You can use the jmod tool to develop JMOD files and also list the content of the existing JMOD flies. This Java programming command lets you aggregate files other than .class files, resources, and metadata.
jlink [options] --module-path modulepath --add-modules module [,module...]
You can use the jlink command to assemble and optimize an array of modules and their dependencies into a personalized run-time image. The command links the modules along with their transitive dependencies to establish a custom runtime image.
jar [OPTION...] [ [--release VERSION] [-C dir] files] ...
The jar command is a very useful command. It creates an archive for classes and resources, also manipulates and restores individual classes or resources from respective classes. The jar command is more or less a general-purpose archiving and compression tool. Its operation is based on the ZLIB or ZIP compression formats.
appletviewer [options] url...
You use the appletviewer tool when launching the AppletViewer and operating applets outside the web browser. Although it is widely used and available and supported by JDK 9, the future of Applet API is uncertain and other options such as Java Web Start or self-contained applications are worth exploring.
Java command is technically used to launch any java application.
Examples:
For executing a class;
java [options] mainclass [args...]
For executing JAR file;
java [options] -jar jarfile [args...]
For executing the main class defined in a module;
java [options] [--module-path modulepath] --module module[/mainclass] [args...]
This command starts a java application by activating the Java Runtime Environment (JRE), enabling the specified class, and then calling the specified class’s main () method.
Javadoc [options] [packagenames] [sourcefiles] [@files]
You use the Javadoc command and its options to seamlessly generate HTML pages or API documentation from a given set of Java source files. This command parses the declarations and documentation comments in an array of java source files and produces the corresponding HTML pages that, by default settings, describe the public and protected classes, interfaces, fields, and nested classes.
You can use this tool to automatically generate c header and source files from a java class
javah [options] fully-qualified-class-name ...
The c headers and source files generated are used to implement the native methods and to reference an object’s instance variable from the corresponding native source code.
jstatd [options ]
You use the jstatd command to observe the creation and termination of an instrumented Java Hotspot VM. This command requires the RMI server application and registry on the localhost.
jconsole [-interval=n] [-notile] [-plugin path] [-version] [connection ... ] [-J input argument
jconsole -help
You can use the jconsole command to launch a graphical console to monitor and manage all java applications. Java console commands are very recurring in a modern developer’s world.
schemagen [ options ] java-files
You can use the scemagen command to generate a schema for every corresponding namespace that is referenced in your Java classes.
public static int min(int a1, int b2)
Java min() is an inbuilt process that gives the lowest value of two entered numbers. It is received from the package called java.lang.math. The parameters are accepted in the types double, int, long, and float. Also, this process can be overloaded, and there are particular requirements for executing this process. If both arguments entered as the procedure’s parameters are negative, then the outcome produced will be the one with a more increased importance. That is, it will be more consolidated to the –ve(negative) perpetuity.
public static void shuffle(List<?> list)
Java has numerous commands to execute various processes. One of them is the shuffle function or command. Shuffle is public in numerous other languages like Python. The shuffle is utilized to rearrange the group components. It unsystematically permutes the index components handed in parameters. There are two techniques to rearrange in Java one is utilizing the group shuffle process, and another is by utilizing random classes. The group shuffle process can also be dubbed in two forms, one with a spontaneous parameter to define randomness and another without a parameter.
addAll(int index, Collection<? extends E> c)
In Java ArrayList, there is a technique addAll() that allows for appending every object public in the argument array to the index that is following in the end. By utilizing the iterator of the group pack, the appended objects will be collected. In addition to that, this process first makes certain that there is adequate room on the index. If good space is not present, it will be cultivated by counting spaces in the current array. After this only, objects will be inserted into the ending of the index. Even though it is feasible to count any sort of component in the array list, it is most useful to add elements of a particular type available in the given instance.
strictfp class example1{
}
The preliminary operation of strictfp in Java is to deliver the exact outcome on every platform when floating-point parameters are in process. When computing floating points on different platforms, the outcomes can differ due to the hardware’s power of processing floating-point by CPU. Strictfp assures that users obtain identical floating-point results on all platforms. The use of strictfp makes certain that when the identical code is run on various platforms, the outcome shall not be exploited due to various accuracy, which functions nicely with more prominent accuracy platforms. Comprehend strictfp as FP Strict, indicating Floating Point Strict.
Timestamp(long time)
Java Timestamp comes under the delicate wrapper of java.util.Date and permits it to be identified as a SQL TIMESTAMP type significance by the JDBC API. Timestamp keeps functions like configuration and parsing to help run the syntax of JDBC for timestamp parameters. Functioning of timestamp role in Java: timestamp can be utilized in a bunch of processes. Timestamp also comes under the mix of class java.util.Date and includes a particular nanosecond of importance. The accumulated values are of vital seconds in java.util.Date element.
wsimport [ options ] wsdl_URI
This command pattern is used to generate Java API for the XML Web Services portable artifacts. All the artifacts can be packaged in a compressed form in a WAR file with the Web Service Description Language (WSDL) file or in schema files and the endpoint implementation is ready for deployment.
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