Java Articles - Page 203 of 440

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

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 More

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 More

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).Casting in JavaConverting one primitive data type into another is known as type casting.Exampleimport java.util.Scanner; public class TypeCastingExample {    public static void main(String args[]){       Scanner sc = new Scanner(System.in);       System.out.println("Enter an integer value: ");       int i = sc.nextInt();       long num = i;       System.out.println("Value of the given integer: "+num);    } }OutputEnter an integer ... Read More

Creating an exact copy of an existing object in the memory is known as cloning.The clone() method of the class java.lang.Object accepts an object as a parameter, creates and returns a copy of it (clones).In order to use this method, you need to make sure that your class implements the Cloneable interface.Example Live Demoimport java.util.Scanner; public class CloneExample implements Cloneable {    private String name;    private int age;    public CloneExample(String name, int age){       this.name = name;       this.age = age;    }    public void displayData(){       System.out.println("Name : "+this.name);     ... Read More

Using loops in programming languages we can execute a set of statements repeatedly. Java provides various loops namely while loop, for loop and the do while loop.The for statement contains an initialization statement, a condition and, an increment or decrement operation.Initializing statement − The initialization determines the starting value of the loop.Condition − The condition in for loop is a statement returning a boolean value. This condition determines the exit value of the loop. It is executed before the statements of the loop.Increment and decrement − Using this the loop will be incremented or decremented to the next value.After initializing ... Read More

In this article, we will learn how to limit the number of characters inside a JTextField in Java. Whether you're creating a form for phone numbers, zip codes, or usernames, controlling the maximum number of characters is important for data validation. JTextField A JTextField is one of the most important Swing components that allows the user to an input text value in a single line format. We can restrict the number of characters that the user can enter into a JTextField can be achieved by using the PlainDocument class. PlainDocument Class PlainDocument is a subclass that extends the AbstractDocument, a ... Read More

Java provides two operators namely ++ and --, to increment and decrement values by 1 respectively.There are two variants of these operators −Pre-increment/decrement − This form, increments/decrements the value first, and then performs the specified operation.ExampleIn the following example, the initial value of the variable i is 5. We are printing the incremented value of it using the pre increment operator.Since we are using the pre increment operator, the value of i is incremented then printed. Live Demopublic class ForLoopExample {    public static void main(String args[]) {       int i = 5;       System.out.println(++i);     ... Read More

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 More

The instanceof operator in Java is used to find whether a reference is an instance of a Type i.e. class or an interface.Example Live Demopublic class InstanceOfExample {    public static void main(String args[]) {       String str = "hello";       boolean bool = str instanceof String;       System.out.println(bool);    } }OutputtrueLegal operands of the instanceof operatorThe following are the only legal operands of the instanceof operator −Left operand − It must be a reference representing an object.Right operand − It must be the name of Java class or, interface.Except these two if you use ... Read More