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Articles on Trending Technologies
Technical articles with clear explanations and examples
Java Program to validate if a String contains only numbers
To validate if a String has only numbers, you can try the following codes. We have used the matches() method in Java here to check for number in a string.Examplepublic class Demo { public static void main(String []args) { String str = "978"; System.out.println("Checking for string that has only numbers..."); System.out.println("String: "+str); if(str.matches("[0-9]+") && str.length() > 2) System.out.println("String has only numbers!"); else System.out.println("String consist of characters as well!"); } }OutputChecking for string that has only numbers... String: ...
Read MoreCheck whether the entered value is a letter or not in Java
To check whether the entered value is a letter or not in Java, use the Character.isLetter() method.We have a value to be checked.char val = 'D';Now let us use the Character.isLetter() method.if (Character.isLetter(val)) { System.out.println("Character is in Lowercase!"); }else { System.out.println("Character is in Uppercase!"); }Let us see the complete example now to check for letter.Examplepublic class Demo { public static void main(String []args) { System.out.println("Checking whether the given value is a Letter or not..."); char val = 'D'; System.out.println("Value: "+val); if (Character.isLetter(val)) { ...
Read MoreFormatter Specifier for Octal and Hexadecimal in Java
For Formatter, import the following package −import java.util.Formatter;Now create a Formatter object like this −Formatter f1 = new Formatter(); Formatter f2 = new Formatter(); Formatter f3 = new Formatter();If you want a Format specifier for Octal, use %o −f3.format("Octal values %o %o %o", 15, 55, 78);If you want a Format specifier for Hexadecimal, use %x −f2.format("Hexadecimal values %x %x %x", 24, 98, 110);The following is an example −Exampleimport java.util.Formatter; public class Demo { public static void main(String args[]) { Formatter f1 = new Formatter(); Formatter ...
Read MoreReturn all system properties in Java
To return all the system properties in Java, firstly use the System.getProperties() method.java.util.Properties prop = System.getProperties();After that, use the list() method to list all of them.prop.list(System.out);Examplepublic class MainClass { public static void main(String[] args) { java.util.Properties prop = System.getProperties(); prop.list(System.out); } }Outputjava.runtime.name=OpenJDK Runtime Environment sun.boot.library.path=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0... java.vm.version=25.141-b16 java.vm.vendor=Oracle Corporation java.vendor.url=http://java.oracle.com/ path.separator=: java.vm.name=OpenJDK 64-Bit Server VM file.encoding.pkg=sun.io user.country=US sun.java.launcher=SUN_STANDARD sun.os.patch.level=unknown java.vm.specification.name=Java Virtual Machine Specification user.dir=/home/cg/root/3757524 java.runtime.version=1.8.0_141-b16 java.awt.graphicsenv=sun.awt.X11GraphicsEnvironment java.endorsed.dirs=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0... os.arch=amd64 java.io.tmpdir=/tmp line.separator= java.vm.specification.vendor=Oracle Corporation os.name=Linux sun.jnu.encoding=UTF-8 java.library.path=/home/cg/root/GNUstep/Library/Librari... java.specification.name=Java Platform API Specification java.class.version=52.0 sun.management.compiler=HotSpot 64-Bit Tiered Compilers os.version=3.10.0-862.9.1.el7.x86_64 user.home=? user.timezone= java.awt.printerjob=sun.print.PSPrinterJob file.encoding=UTF-8 java.specification.version=1.8 user.name=? java.class.path=/home/cg/root/GNUstep/Library/Librari... java.vm.specification.version=1.8 sun.arch.data.model=64 java.home=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0... sun.java.command=MainClass java.specification.vendor=Oracle Corporation user.language=en awt.toolkit=sun.awt.X11.XToolkit ...
Read MoreFormat Specifier for Hash Code in Java
Format specifier for Hash Code us %h.Firstly, create a new object for Formatter and Calendar −Formatter f = new Formatter(); Calendar c = Calendar.getInstance();For hash code −f.format("%h", c)The following is an example that finds the hash code −Exampleimport java.util.Calendar; import java.util.Formatter; public class Demo { public static void main(String args[]) { Formatter f = new Formatter(); Calendar c = Calendar.getInstance(); System.out.println("Hash Code: "+f.format("%h", c)); } }OutputHash Code: 4b899958
Read MoreJava Program to check whether the entered character a digit, white space, lower case or upper case character
To check whether the entered character is a digit, whitespace, lowercase or uppercase, you need to check for the ASCII values.Let’s say we have a value in variable “val”, which is to be checked.For Lower Case.if(val >= 97 && val = 65 && val = 48 && val = 97 && val = 65 && val = 48 && val = 97 && val = 65 && val = 48 && val
Read MoreReplace All Elements Of ArrayList with with Java Collections
In order to replace all elements of ArrayList with Java Collections, we use the Collections.fill() method. The static void fill(List list, Object element) method replaces all elements in the list with the specified element in the argument.Declaration −The java.util.Collections.fill() method is declared as follows −public static void fill(List
Read MoreGet the default system properties in Java
To return all the default systems properties in Java, firstly use the System.getProperties() method.java.util.Properties prop = System.getProperties();After that, use the list() method to list all of them.prop.list(System.out);Examplepublic class Demo { public static void main(String[] args) { java.util.Properties prop = System.getProperties(); System.out.println("Here are the Properties:"); prop.list(System.out); } }OutputHere are the Properties: java.runtime.name=OpenJDK Runtime Environment sun.boot.library.path=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0... java.vm.version=25.141-b16 java.vm.vendor=Oracle Corporation java.vendor.url=http://java.oracle.com/ path.separator=: java.vm.name=OpenJDK 64-Bit Server VM file.encoding.pkg=sun.io user.country=US sun.java.launcher=SUN_STANDARD sun.os.patch.level=unknown java.vm.specification.name=Java Virtual Machine Specification user.dir=/home/cg/root/3757524 java.runtime.version=1.8.0_141-b16 java.awt.graphicsenv=sun.awt.X11GraphicsEnvironment java.endorsed.dirs=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0... os.arch=amd64 java.io.tmpdir=/tmp line.separator= java.vm.specification.vendor=Oracle Corporation os.name=Linux sun.jnu.encoding=UTF-8 java.library.path=/home/cg/root/GNUstep/Library/Librari... java.specification.name=Java Platform API Specification java.class.version=52.0 sun.management.compiler=HotSpot 64-Bit Tiered Compilers os.version=3.10.0-862.9.1.el7.x86_64 user.home=? user.timezone= java.awt.printerjob=sun.print.PSPrinterJob file.encoding=UTF-8 ...
Read MoreVertically align numeric values in Java using Formatter
To vertically align numeric values in Java, use Formatter. For working with Formatter class, import the following package.import java.util.Formatter;Take an array −double arr[] = { 2.5, 4.8, 5.7, 6.5, 9.4, 8.4, 9.5, 10.2, 11.5 };While displaying this double array values, use the %f to set spaces −for (double d : arr) { f.format("%12.2f %12.2f %12.2f", d, Math.ceil(d), Math.floor(d)); }Above, we have also set the decimal places i.e. 12.2f is for 2 decimal places.The following is an example −Exampleimport java.util.Formatter; public class Demo { public static void main(String[] argv) throws Exception { ...
Read MoreStore unicode in a char variable in Java
To store Unicode in a char variable, simply create a char variable.char c;Now assign unicode.char c = '\u00AB';The following is the complete example that shows what will get displayed: when Unicode is stored in a char variable and displayed.Examplepublic class Demo { public static void main(String []args) { int a = 79; System.out.println(a); char b = (char) a; System.out.println(b); char c = '\u00AB'; System.out.println(c); } }Output79 O «
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