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Programming Articles
Page 2543 of 2547
What is the difference between a Java method and a native method?
A native method is the one whose method implementation is done in other languages like c++ and Java. These programs are linked to Java using JNI or JNA interfaces. The difference between normal method and native method is That the native method declaration contains native keyword and, the implementation of the method will be other programming language. Example Tester.java public class Tester { public native int getValue(int i); public static void main(String[] args) { System.loadLibrary("Tester"); System.out.println(new Tester().getValue(2)); ...
Read MoreWhat is a method in Java that ends in a semicolon and has no method body?
An abstract method is the one which has no definition and declared abstract. In short, an abstract method contains only method signature without body. To use this method, you need to inherit this method by extending the class and provide the method definition. Example public abstract class Employee{ private String name; private String address; private int number; public abstract double computePay(); }
Read MoreWhat are number format exceptions in Java?
This Exception happens once you associated convert a string variable in an incorrect format to a whole number (numeric format) that's not compatible with one another. Example public class Test { public static void main(String[] args) { int data = Integer.parseInt("hello"); } } Output Exception in thread "main" java.lang.NumberFormatException: For input string: "hello" at java.lang.NumberFormatException.forInputString(Unknown Source) at java.lang.Integer.parseInt(Unknown Source) at java.lang.Integer.parseInt(Unknown Source) at a6.dateAndTime.Test.main(Test.java:5)
Read MoreWhat is the difference between javac, java commands?
The javac command is used to compile Java programs, it takes .java file as input and produces bytecode. Following is the syntax of this command. >javac sample.java The java command is used to execute the bytecode of java. It takes byte code as input and runs it and produces the output. Following is the syntax of this command. >java sample Let us consider an example create a Sample Java program with name Sample.java Sample.java public class Sample { public static void main(String args[]) { System.out.println("Hi welcome ...
Read MoreWhat is the difference between System.out, System.in and System.err streams in Java?
All the programming languages provide support for standard I/O where the user's program can take input from a keyboard and then produce an output on the computer screen. Similarly, Java provides the following three standard streams:Standard Input: This is used to feed the data to user's program and usually a keyboard is used as a standard input stream and represented as System.in.Standard Output: This is used to output the data produced by the user's program and usually a computer screen is used for standard output stream and represented as System.out.Standard Error: This is used to output the error data produced ...
Read MoreWhat is Callable interface in Java?
The Callable interface is found in the package java.util.concurrent. The Callable object can return the computed result done by a thread in contrast to a runnable interface which can only run the thread. The Callable object returns a Future object which provides methods to monitor the progress of a task being executed by a thread. The future object can be used to check the status of a Callable and then retrieve the result from the Callable once the thread is done. It also provides timeout functionality.
Read MoreWhat are the platforms that support Java programming language?
Java runs on operating systems such as Windows, Mac OS, and the various versions of UNIX/Linux like HP-Unix, Sun Solaris, Redhat Linux, Ubuntu, CentOS, etc.
Read MoreWhat is meant by Java being an architecture neutral language?
Unlike many other programming languages including C and C++, when Java is compiled, it is not compiled into platform specific machine, rather into platform-independent byte code. This byte code is distributed over the web and interpreted by the Virtual Machine (JVM) on whichever platform it is being run on. Thus when you write a piece of Java code in a particular platform and generated an executable code .class file. You can execute/run this .class file on any system the only condition is that the target system should have JVM (JRE) installed in it. In short, Java compiler generates an architecture-neutral ...
Read MoreWhat is the purpose of System class in Java?
System class belongs to the package java.lang. It cannot be instantiated. A System class provides − standard output. error output streams. standard input and access to externally defined properties and environment variables. A utility method for quickly copying a portion of an array. a means of loading files and libraries. Following are the fields for java.lang.System class − static PrintStream err − This is the "standard" error output stream. static InputStream in − This is the "standard" input stream. static PrintStream out − This is the "standard" output stream.
Read MoreWhat is meant by Java being a dynamic language?
Java is considered to be more dynamic than C or C++ since it is designed to adapt to an evolving environment. Java programs can carry an extensive amount of run-time information that can be used to verify and resolve accesses to objects at run-time.
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