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Java Articles
Page 86 of 450
Java Program to return a Date set to the first possible millisecond of the day after midnight
Let us first set the calendar object.Calendar calendar = Calendar.getInstance();Use the getMinimum() method in Java to return the minimum value for the given calendar field. We will use it to set the minute, hours second and milliseconds.For hour and minute.calendar.set(Calendar.HOUR_OF_DAY, calendar.getMinimum(Calendar.HOUR_OF_DAY)); calendar.set(Calendar.MINUTE, calendar.getMinimum(Calendar.MINUTE));For second and milliseconds.// second calendar.set(Calendar.SECOND, calendar.getMinimum(Calendar.SECOND)); // millisecond calendar.set(Calendar.MILLISECOND, calendar.getMinimum(Calendar.MILLISECOND));The following is an example that returns a Date set to the first possible millisecond of the day after midnight.Exampleimport java.util.Calendar; import java.util.GregorianCalendar; public class Demo { public static void main(String[] argv) throws Exception { Calendar calendar = Calendar.getInstance(); // hour ...
Read MoreConvert double primitive type to a Double object in Java
To convert double primitive type to a Double object, you need to use Double constructor.Let’s say the following is our double primitive.// double primitive double val = 23.78;To convert it to a Double object, use Double constructor.// Double object Double ob = new Double(val);Examplepublic class Demo { public static void main(String args[]) { // double primitive double val = 23.78; // Double object Double ob = new Double(val); System.out.println(ob); } }Output23.78
Read MoreFormat double type in Java
Let’s say we have the following three values −double val1 = 15.546; double val2 = 25.87; double val3 = Math.PI;Let us now format these double-type numbers. Firstly, we are formatting Euler’s number with Math.exp(). After that, we have also evaluated log. The %.3f you can see here is what we used for formatting the numbers.System.out.printf("exp(%.3f) = %.3f%n", val1, Math.exp(val1)); System.out.printf("log = %.3f%n", val1, Math.log(val1));The following is an example where we have also shown other ways to format double in Java.Examplepublic class Demo { public static void main(String args[]) { double val1 = 15.546; ...
Read MorePrecision on a number format in Java
You can include a precision specifier to the following format specifiers −%f %e %g %sOn floating point, the number of decimal places is known.Let’s say we declared a Formatter object −Formatter f1 = new Formatter();Now, we want 3 decimal places. For that, use 1.3f −f1.format("%1.3f", 29292929.98765432);The above will return the number with 3 decimal places −29292929.988The following is the final example −Exampleimport java.util.Formatter; public class Demo { public static void main(String args[]) { Formatter f1, f2, f3; f1 = new Formatter(); f1.format("%1.3f", 29292929.98765432); System.out.println(f1); f2 = new Formatter(); f2.format("%1.7f", 29292929.98765432); System.out.println(f2); ...
Read MoreJava Program to add leading zeros to a number
To add leading zeros to a number, you need to format the output. Let’s say we need to add 4 leading zeros to the following number with 3 digits.int val = 290;For adding 4 leading zeros above, we will use %07d i.e. 4+3 = 7. Here, 3, as shown above, is the number with 3 digits.String.format("%07d", val);The following is the final example.Exampleimport java.util.Formatter; public class Demo { public static void main(String args[]) { int val = 290; System.out.println("Integer: "+val); String formattedStr = String.format("%07d", val); System.out.println("With leading zeros = " + formattedStr); } }OutputInteger: 290 With leading zeros = 0000290
Read MoreGet all digits from a string in Java
Let’s say the following is our string.String str = "DEMO98 TE4567XT";To display only the digits from the above string, we have used the replaceAll() method and replace all the characters with empty.str.replaceAll("\D", ""))The following is the final example that displays only digits from the string.Examplepublic class Demo { public static void main(String[] args) { String str = "DEMO98 TE4567XT"; System.out.println("String = "+str); System.out.println("Displaying digits: "+str.replaceAll("\D", "")); } }OutputString = DEMO98 TE4567XT Displaying digits: 984567
Read MoreConcatenate null to a string in Java
To concatenate null to a string, use the + operator.Let’s say the following is our string.String str = "Demo Text";We will now see how to effortlessly concatenate null to string.String strNULL = str + "null";The following is the final example.Examplepublic class Demo { public static void main(String[] args) { String str = "Demo Text"; System.out.println("String = "+str); String strNULL = str + "null"; System.out.println("String concatenated with NULL: "+strNULL); } }OutputString = Demo Text String concatenated with NULL: Demo Textnull
Read MoreDisplay the Operating System name in Java
Use the System.getProperty() method in Java to get the Operating System name.It’s syntax is −String getProperty(String key)Above, the key is the name of the system property. Since, we want the OS name, therefore we will add the key as −os.nameExamplepublic class Demo { public static void main(String[] args) { System.out.print("Operating System: "); System.out.println(System.getProperty("os.name")); } }OutputOperating System: Linux
Read MoreTokenizing a String in Java
We have the following string −String str = "This is demo text, and demo line!";To tokenize the string, let us split them after every period (.) and comma (,)String str = "This is demo text, and demo line!";The following is the complete example.Examplepublic class Demo { public static void main(String[] args) { String str = "This is demo text, and demo line!"; String[] res = str.split("[, .]", 0); for(String myStr: res) { System.out.println(myStr); } } }OutputThis is demo text and demo line!
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 ...
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