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Object Oriented Programming Articles
Page 453 of 589
Advantages and disadvantages of arrays in Java
BenefitsEasier access to any element using the index.Easy to manipulate and store large data.DisadvantagesFixed size. Can not be increased or decrease once declared.Can store a single type of primitives only.
Read MoreWhat are all the ways an object can be created in Java?
You can create an objectUsing new keyword.Sample obj = new Sample();Using the newInstance() method and Class.forName() method.Sample obj2 = (Sample) Class.forName("Sample").newInstance();Using the clone() method by implementing Cloneable Interface (marker).Sample obj3 = (Sample) obj1.clone();Using class loader.Object obj4 = Sample.class.getClassLoader().loadClass("Sample");Using the constructor class from lang.reflect.Class cls = Sample.class; Constructor obj = cls.getDeclaredConstructors()[0]; Sample obj5 = (Sample) obj.newInstance();
Read MoreHow to count Java comments of a program that is stored in a text file?
You can read the contents of a file using the Scanner class and You can find the comments in a particular line using contains() method.Exampleimport java.io.*; import java.util.Scanner; public class FindingComments { public static void main(String[] args) throws IOException { Scanner sc = new Scanner(new File("HelloWorld")); String input; int single = 0; int multiLine = 0; while (sc.hasNextLine()) { input = sc.nextLine(); if (input.contains("/*")) { multiLine ++; ...
Read MoreWhat are variadic functions in Java?
Methods which uses variable arguments (varargs, arguments with three dots) are known as variadic functions. Example public class Sample { void demoMethod(String... args) { for (String arg: args) { System.out.println(arg); } } public static void main(String args[] ){ new Sample().demoMethod("ram", "rahim", "robert"); new Sample().demoMethod("krishna", "kasyap"); } } Output ram rahim robert krishna kasyap
Read MoreJava labelled for loop
Following program is using labeled for loops. Example public class Tester { public static void main(String args[]) { first: for (int i = 0; i
Read MoreJava labelled statement
Yes. Java supports labeled statements. You can put a label before a for statement and use the break/continue controls to jump to that label. Example See the example below. public class Tester { public static void main(String args[]) { first: for (int i = 0; i
Read MoreJava Conversions and Promotions
We can convert one data types into another data type using casting. Narrowing ConversionNarrowing refers to passing a higher size data type like int to a lower size data type like short. It may lead to data loss. Following program output will be 44.public class MyFirstJavaProgram { public static void main(String []args) { int a = 300; byte b = (byte)a; // narrowing System.out.println(b); } }Widening/Promotion ConversionWidening refers to passing a lower size data type like ...
Read MoreJava overflow and underflow
OverflowOverflow occurs when we assign such a value to a variable which is more than the maximum permissible value.UnderflowUnderflow occurs when we assign such a value to a variable which is less than the minimum permissible value.JVM does not throw any exception in case Overflow or underflow occurs, it simply changes the value. Its programmer responsibility to check the possibility of an overflow/underflow condition and act accordingly. Example (Overflow)Consider the case of int variable, it is of 32 bit and any value which is more than Integer.MAX_VALUE (2147483647) is rolled over. For example, Integer.MAX_VALUE + 1 returns -2147483648 (Integer.MIN_VALUE).As int ...
Read MoreJava variable declaration best practices
Following are the best practices while declaring a variable.Variables names should be short or long enough as per the scope. For example, loop counter variable, i is fine whereas employee as a loop variable.Specific words should not be used as equals, compare, data.Use meaningful names which can explain the purpose of the variable. For example cnt Vs counter.Don't use _ to declare a variable name, Use camel casing. For example, employeeName is better than employee_name.Each organization has its own syntax specific standards. Follow those rules to maintain consistency and readability.
Read MoreWhy is Java slower than C++ programs?
Modern Java is quite fast and is comparable to C++ code base but it still takes lot of memory. Slowness of Java programs is primarily because of bad programming practices. But following areas are where Java can be improved.Java libraries are written keeping readability and correctness in mind, not performance.Slow String based operations as Strings are UTF-16 encoded objects and are immutable. So more String are used, more memory is required.Boundary checks on arrays also make its operations bit slow.I/O Stream operations are slow considering synchronization checks on each access.Lacking low level functionality like C also attributes to slowness in ...
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