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Java Articles
Page 409 of 450
Are true and false keywords in java?
Keywords − Keywords in Java convey a special meaning to the compiler therefore, these cannot be used as identifiers. Java provides a set of 50 keywords.abstractcontinuefornewswitchassertdefaultgotopackagesynchronizedbooleandoifprivatethisbreakdoubleimplementsprotectedthrowbyteelseimportpublicthrowscaseenuminstanceofreturntransientcatchextendsintshorttrycharfinalinterfacestaticvoidclassfinallylongstrictfpvolatileconstfloatnativesuperwhileReserved words − Among 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).The true false and null − True, false and null represents certain values in Java, they are used as literals. They are not considered as keywords.Still, you cannot use them as identifiers in Java if you try to do so, a compile time error will ...
Read MoreExplain widening with objects in Java.
Java provides various datatypes to store various data values. It provides 7 primitive datatypes (stores single values) namely, boolean, byte, char, short, int, long, float, double and, reference datatypes (arrays and objects).Type Casting/type conversion − Converting one primitive datatype into another is known as type casting (type conversion) in Java. You can cast the primitive datatypes in two ways namely, Widening and, Narrowing.Widening − Converting a lower datatype to a higher datatype is known as widening. In this case the casting/conversion is done automatically therefore, it is known as implicit type casting. In this case both datatypes should be compatible ...
Read MoreExplain narrowing with object in Java.
Java provides various datatypes to store various data values. It provides 7 primitive datatypes (stores single values) namely, boolean, byte, char, short, int, long, float, double and, reference datatypes (arrays and objects).Type Casting/type conversion −Converting one primitive datatype into another is known as type casting (type conversion) in Java. You can cast the primitive datatypes in two ways namely, Widening and, Narrowing.Narrowing − Converting a higher datatype to a lower datatype is known as narrowing. In this case the casting/conversion is not done automatically, you need to convert explicitly using the cast operator “( )” explicitly. Therefore, it is known ...
Read MoreHow to convert an object array to an integer array in Java?
You can convert an object array to an integer array in one of the following ways −By copying each element from integer array to object array −Exampleimport java.util.Arrays; public class ObjectArrayToStringArray { public static void main(String args[]){ Object[] objArray = {21, 58, 69, 33, 65}; int length = objArray.length; int intArray[] = new int[length]; for(int i=0; i
Read MoreIs main method compulsory in Java?
To compile a program, you doesn’t really need a main method in your program. But, while execution JVM searches for the main method. In the Java the main method is the entry point Whenever you execute a program in Java JVM searches for the main method and starts executing from it.The main method must be public, static, with return type void, and a String array as argument.public static int main(String[] args){ }You can write a program without defining a main it gets compiled without compilation errors. But when you execute it a run time error is generated saying “Main method ...
Read MoreWhat is instance variable hiding in Java?
Whenever you inherit a superclass a copy of superclass’s members is created at the subclass and you using its object you can access the superclass members.If the superclass and the subclass have instance variable of same name, if you access it using the subclass object, the instance variables of the subclass hides the instance variables of the superclass irrespective of the types. This mechanism is known as field hiding or, instance variable hiding.But, since it makes code complicated field hiding is not recommended.ExampleIn the following example we have two classes Super and Sub one extending the other. They both have ...
Read MoreWhat are the default array values in Java?
In Java arrays are the reference types which stores multiple elements of the same datatype. You can create an array just like an object using the new keyword −type[] reference = new type[10];or, directly using the flower brackets ({}).int [] myArray = {10, 20, 30, 40, 50}When you create instance variables in Java you need to initialize them, else the compiler will initialize on your behalf with default values.Similarly, if you create an array as instance variable, you need to initialize it else the compiler initializes with default values which are −Integer − 0Byte − 0Float − 0.0Boolean − falseString/Object ...
Read MoreJava Program to find all angles of a triangle
To find the angles of a triangle we can use sin/cosine rules according to cosine rule −cos A = (b^2 + c^2 - a^2)/2bcwhere A, B , C are the vertices and a, b, c are the sides of the given triangle then, angles of the triangle when the sides a, b, c given are −angleAtA = acos((b^2 + c^2 - a^2)/(2bc)) angleAtB = acos((a^2 + c^2 - b^2)/(2ac)) angleAtC = acos((a^2 + b^2 - c^2)/(2ab))
Read MoreWhat is ODBC?
ODBC stands for Oracle Database Connectivity. It is an API which is used to access different databases.The OFBC driver uses the Open Database connectivity interface provided by Microsoft to communicate with the databases. It is independent of Databases and platforms and operating systems. Once you develop an application using ODBC you can run it on other platforms with little change in Data access code. ODBC uses SQL syntax and it is based on Open call level interface.
Read MoreWhat is the difference between include action and include directive in JSP?
include action lets you insert files into the page being generated. The syntax looks like this −Unlike the include directive, which inserts the file at the time the JSP page is translated into a servlet, this action inserts the file at the time the page is requested.
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