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Programming Articles
Page 2542 of 2547
What is the difference between compile time errors and run time errors in Java?
Compile time errors are syntactical errors in the code which hinders it from being compiled. Example public class Test{ public static void main(String args[]){ System.out.println("Hello") } } Output C:\Sample>Javac Test.java Test.java:3: error: ';' expected System.out.println("Hello") An exception (or exceptional event) is a problem that arises during the execution of a program. When an Exception occurs the normal flow of the program is disrupted and the program/Application terminates abnormally, which is not recommended, therefore, these exceptions are to be handled. Example ...
Read MoreWhat is meant by Java being 'write once run anywhere' 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, If you have a ...
Read MoreIs it necessary that a try block should be followed by a catch block in Java?
Not necessarily catch, a try must be followed by either catch or finally block. Example import java.io.File; public class Test{ public static void main(String args[]){ System.out.println("Hello"); try{ File file = new File("data"); } } } Output C:\Sample>Javac Test.java Test.java:5: error: 'try' without 'catch', 'finally' or resource declarations try{ ^ 1 error
Read MoreWhat are checked exceptions in Java?
A checked exception is an exception that occurs at the time of compilation, these are also called as compile time exceptions. These exceptions cannot simply be ignored at the time of compilation; the programmer should take care of (handle) these exceptions. if you use FileReader class in your program to read data from a file, if the file specified in its constructor doesn't exist, then a FileNotFoundException occurs, and the compiler prompts the programmer to handle the exception. Example import java.io.File; import java.io.FileReader; public class FilenotFound_Demo { public static void main(String args[]) { ...
Read MoreWhat is a JAR file?
A java archive file is a file format/ archiving tool which contains all the components of an executable Java application. All the predefined libraries are available in this format. To include any of these (other than rt.jar) in to your project you need to set the class path for this particular JAR file. You can create a JAR file using the command line options or using any IDE’s. Creating a Jar file You can create a Jar file using the jar command as shown below. jar cf jar-file input-file(s) Let us consider an example, create a Sample Java ...
Read MoreWhat are native methods in Java and where are they used?
A native method in Java is a method whose implementation is written in other languages such as c and c++. The ‘native’ keyword is used before a method to indicate that it is implemented in other language.
Read MoreWhat 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 MoreIs it possible to use Python modules in Octave?
There is no straightforward way to do this. But it is possible to run a Python program and parse the output. You can execute any shell command using the function system (cmd, flag). The second argument is optional. If it is present, the output of the command is returned by system as a string. If it is not supplied, any output from the command is printed, with the standard output filtered through the pager. For example,output = system ("python /path/to/your/python/script.py", 1)
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 MoreHow to prohibit a Python module from calling other modules?
You can use "Sandboxed Python". A "Sandboxed Python" would let you permit or forbid modules, limit execution slices, permit or deny network traffic, constrain filesystem access to a particular directory (floated as "/"), and so on. It is also referred to as RestrictedExecution. There are many ways to implement sandboxing on Python. You could Modify the CPython Runtime, Use Another Runtime, Use Operating System Support, etc to implement such a sandbox. You can read more about sandboxing at: https://wiki.python.org/moin/SandboxedPythonPypi has a package called RestrictedPython(https://pypi.python.org/pypi/RestrictedPython) that is a defined subset of the Python language which allows to provide a program input ...
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