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KeywordsKeywords in Java convey a special meaning to the compiler therefore, these cannot be used as identifiers. Java provides a set of 50 keywords.abstractcontinuefornewswitchassertdefaultgotopackagesynchronizedbooleandoifprivatethisbreakdoubleimplementsprotectedthrowbyteelseimportpublicthrowscaseenuminstanceofreturntransientcatchextendsintshorttrycharfinallongstrictfpvolatileconstfloatnativesuperwhileReserved wordsAmong the list of key words list mentioned above the key words goto and const are currently not in use. They are reserved words (for the future use).
Before running Java programs on your machine you need to set two environment variables namely, PATH − The path environment variable is used to specify the set of directories which contains execution programs.When you try to execute a program from command line, the operating system searches for the specified program in the current directly, if available, executes it.In case the programs are not available in the current directory, operating system verifies in the set of directories specified in the ‘PATH’ environment variable.CLASSPATH − The classpath environment variable is used to specify the location of the classes and packages.When we try ... Read More
To generate Java docs for your project you need to write the required information about the field, method or class as./** * * The method prints a simple message on the Console. * */Then to generate the document follow the steps given below −Step 1 − Open eclipse, select the option Project →Generate Javadoc.Step 2 − Select the javadoc.exe file from the bin folder of java installation directory, select the destination folder for the generated java doc and select Next.Step 3 − Type the title of the documentation in the Document title and select thefinish button.Step 4 ... Read More
Java is not dependent on any specific operating system so Java applications cannot depend on the platform dependent native libraries, therefore, instead of those Java provides a set of dynamically loaded libraries that are common to modern operating systems.These libraries provide –Container classes and Regular Expressions.Interfaces for tasks that depend on the hardware of the OS such as network and file access.In case, the underlying platform does not support certain feature of Java then, these libraries surpass that specific feature if needed.
Java Standard Edition provides 14 packages namely –applet − This package provides classes and methods to create and communicate with the applets.awt− This package provides classes and methods to create user interfaces.beans− This package contains classes and methods to develop components based on java beans. io− This package contains classes and methods to read and write data standard input and output devices, streams and files.lang− This package contains the fundamental classes, methods, and, interfaces of Java language.math− This package contains classes and methods which helps you to perform arithmetic operations using the Java language.net− This package provides classes to implement networking ... Read More
The JsonGenerator interface can be used to write the JSON data to an output source in a streaming way. We can create or implement a JSON array using the writeStartArray() method of JsonGenerator, this method writes the JSON name/start array character pair within the current object context. The writeStartObject() method writes the JSON start object character, and valid only in an array context and the writeEnd() method writes the end of the current context.SyntaxJsonGenerator writeStartArray(String name)Exampleimport java.io.*; import javax.json.*; import javax.json.stream.*; public class JsonGeneratorTest { public static void main(String[] args) throws Exception { StringWriter writer = new ... Read More
A fully object-oriented language needs to have all the 4 oops concepts. In addition to that, all predefined and, user-defined types must be objects and, all the operations should be performed only by calling the methods of a class.Though java follows all the four object-oriented concepts,Java has predefined primitive data types (which are not objects).You can access the members of a static class without creating an object of it.Therefore, Java is not considered as fully object-oriented Technology.
Java Virtual machine is the program which accepts .class files as input and converts this to system executable code.The class loader is a module in JVM it loads, links and, initialize a program.Loads the class into the memory.Verifies the byte code instructions.Allocates memory for the program.
We may sometimes need to append zeros as string to various data elements in python. There may the reason for formatting and nice representation or there may be the reason for some calculations where these values will act as input. Below are the methods which we will use for this purpose.Using format()Here we take a DataFrame and apply the format function to the column wher we need to append the zeros as strings. The lambda method is used to apply the function repeatedly.Exampleimport pandas as pd string = {'Column' : ['HOPE', 'FOR', 'THE', 'BEST']} dataframe=pd.DataFrame(string) print("given column is ") print(dataframe) ... Read More
Tkinter, which is the GUI library for python programming has a feature to add images to the GUI buttons. This is useful for users to remember the symbols in the GUI rather than the text in the GUI. In the below Tkinter program we show how we can add an image to a GUI button. The photoimage method from the imageKT module is used. We mention the local path to the image file.Examplefrom tkinter import * from PIL import ImageTk ,Image base = Tk() base.title('Start Button') img=ImageTk.PhotoImage(Image.open ("D:\button.jpg")) lab=Label(image=img) lab.pack() button=Button(base, text='exit', command=base.quit) button.pack() base.mainloop()OutputRunning the above ... Read More