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Articles on Trending Technologies
Technical articles with clear explanations and examples
Get the substring before the last occurrence of a separator in Java
We have the following string with a separator.String str = "David-Warner";We want the substring before the last occurrence of a separator. Use the lastIndexOf() method.For that, you need to get the index of the separator using indexOf()String separator ="-"; int sepPos = str.lastIndexOf(separator); System.out.println("Substring before last separator = "+str.substring(0, sepPos));The following is an example.Examplepublic class Demo { public static void main(String[] args) { String str = "David-Warner"; String separator ="-"; int sepPos = str.lastIndexOf(separator); if (sepPos == -1) { System.out.println(""); ...
Read MoreConvert Long to numeric primitive data types in Java
Let’s say we have Long object here.Long myObj = new Long("9879");Now, if we want to convert this Long to short primitive data type. For that, use the in-built shortValue() method −// converting to short primitive types short shortObj = myObj.shortValue(); System.out.println(shortObj);In the same way convert Long to another numeric primitive data type int. For that, use the in-built intValue() method −// converting to int primitive types int intObj = myObj.intValue(); System.out.println(intObj);The following is an example wherein we convert Long to numeric primitive types short, int, float, etc −Examplepublic class Demo { public static void main(String[] args) { ...
Read MoreCount how many times the substring appears in the larger String in Java
Let’s say we have the following string.String str = "Learning never ends! Learning never stops!";In the above string, we need to find out how many times the substring “Learning” appears.For this, loop until the index is not equal to 1 and calculate.while ((index = str.indexOf(subString, index)) != -1) { subStrCount++; index = index + subString.length(); }The following is an example.Examplepublic class Demo { public static void main(String[] args) { String str = "Learning never ends! Learning never stops!"; System.out.println("String: "+str); int subStrCount = 0; String subString = ...
Read MoreCreate a StringBuffer object using a reference stored in a variable of type String in Java
To create a StringBuffer Object, we use the following syntax −StringBuffer s=new StringBuffer();When we create a reference to an object, we use the assignment operator. For example, String s1 = ”hi”; String s2 = s1; // s2 is a reference of s1A program to illustrate the creation of a StringBuffer object using a reference stored in a variable of type String is given below −Examplepublic class Example { public static void main(String args[]) { String input = "hey"; String s1 = input; // creating a reference of the String StringBuffer ...
Read MoreJava Program to display double and single quote in a string
The following are our strings with single and double quote.String str1 = "This is Jack's mobile"; String str2 = ""This is it"!";Above, for single quote, we have to mention it normally like.This is Jack's mobileHowever, for double quotes, use the following and add a slash in the beginning as well as at the end.String str2 = ""This is it"!";The following is an example.Examplepublic class Demo { public static void main(String[] args) { String str1 = "This is Jack's mobile"; String str2 = ""This is it"!"; System.out.println("Displaying Single Quote: "+str1); ...
Read MoreRandom vs Secure Random numbers in Java
Java provides two classes for having random numbers generation - SecureRandom.java and Random.java.The random numbers can be used generally for encryption key or session key or simply password on web server.SecureRandom is under java.security package while Random.java comes under java.util package.The basic and important difference between both is SecureRandom generate more non predictable random numbers as it implements Cryptographically Secure Pseudo-Random Number Generator (CSPRNG) as compare to Random class which uses Linear Congruential Generator (LCG).A important point to mention here is SecureRandom is subclass of Random class and inherits its all method such as nextBoolean(), nextDouble(), nextFloat(), nextGaussian(), nextInt() and ...
Read MoreJava Program to check for Integer overflow
To check for Integer overflow, we need to check the Integer.MAX_VALUE, which is the maximum value of an integer in Java.Let us see an example wherein integers are added and if the sum is more than the Integer.MAX_VALUE, then an exception is thrown.Examplepublic class Demo { public static void main(String[] args) { int val1 = 9898989; int val2 = 6789054; System.out.println("Value1: "+val1); System.out.println("Value2: "+val2); long sum = (long)val1 + (long)val2; if (sum > Integer.MAX_VALUE) { throw new ...
Read MoreSet the base time zone offset to GMT in Java
In order to set the base time zone to GMT in Java, we use the setRawOffset(int offsetMillis) method. The java.util.TimeZone.setRawOffset(int offsetMillis) method set the base timezone offset to GMT.Declaration − The java.util.TimeZone.setRawOffset(int offsetMillis) method is declared as follows −public abstract void setRawOffset(int offsetMillis)where offsetMillis is the given base time zone offset to GMT.Let us set the base timezone offset to GMT in Java −Exampleimport java.util.*; public class Example { public static void main( String args[] ) { // creating default object of TimeZone TimeZone obj = TimeZone.getDefault(); System.out.println("Default timezone object: ...
Read MoreReferencing Subclass objects with Subclass vs Superclass reference
In java inheritance some of the basic rules includes −Object relation of Superclass (parent) to Subclass (child) exists while child to parent object relation never exists.This means that reference of parent class could hold the child object while child reference could not hold the parent object.In case of overriding of non static method the runtime object would evaluate that which method would be executed of subclass or of superclass.While execution of static method depends on the type of reference that object holds.Other basic rule of inheritance is related to static and non static method overriding that static method in java ...
Read MoreJava Program to split a string with dot
Let’s say the following is our string.String str = "Java is a programming language. James Gosling developed it.";We will now see how to split a string using the split() method. Include the delimiter as the parameter.String[] strSplit = str.split("\.");Above, we have split the string with dot as you can see under the split methods parameter.The following is an example.Examplepublic class Demo { public static void main(String[] args) { String str = "Java is a programming language. James Gosling developed it."; System.out.println("String: "+str); String[] strSplit = str.split("\."); System.out.println("Splitting ...
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