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Articles on Trending Technologies
Technical articles with clear explanations and examples
Get current time information in Java
Import the following package for to work with Calendar class in Java, import java.util.Calendar;Create a calendar class now.Calendar cal = Calendar.getInstance();To display entire time information, use the following fields.cal.get(Calendar.HOUR_OF_DAY) cal.get(Calendar.HOUR) cal.get(Calendar.MINUTE) cal.get(Calendar.SECOND) cal.get(Calendar.MILLISECOND)The following is the final example.Exampleimport java.util.Calendar; public class Demo { public static void main(String[] args) { Calendar cal = Calendar.getInstance(); // current date and time System.out.println(cal.getTime().toString()); // time information System.out.println("Hour (24 hour format) : " + cal.get(Calendar.HOUR_OF_DAY)); System.out.println("Hour (12 hour format) : " + cal.get(Calendar.HOUR)); ...
Read MoreValidate city and state with Java Regular Expressions
In order to match the city and state using regular expression, we use the matches method in Java. The java.lang.String.matches() method returns a boolean value which depends on the matching of the String with the regular expression.Declaration − The java.lang.String.matches() method is declared as follows −Examplepublic class Example { public static void main( String[] args ) { System.out.println(city("Mumbai")); System.out.println(state("Goa")); } // validating the city public static boolean city( String c ) { return c.matches( "([a - zA - Z] + |[a - zA - Z] + \s[a ...
Read MoreValidate the ZIP code with Java Regular expressions
In order to match the ZIP code using regular expression, we use the matches method in Java. The java.lang.String.matches() method returns a boolean value which depends on the matching of the String with the regular expression.Declaration − The java.lang.String.matches() method is declared as follows −public boolean matches(String regex)Let us see a program which validates the ZIP code with Java Regular Expressions −Examplepublic class Example { public static void main( String[] args ) { System.out.println(zipIndia("400709")); System.out.println(zipUS("10060")); } // validate zip public static boolean zipIndia( String z ) { ...
Read MoreDifference between TreeMap, HashMap and LinkedHashMap in Java programming
HashMap, TreeMap and LinkedHashMap all implements java.util.Map interface and following are their characteristics.HashMapHashMap has complexity of O(1) for insertion and lookup.HashMap allows one null key and multiple null values.HashMap does not maintain any order.TreeMapTreeMap has complexity of O(logN) for insertion and lookup.TreeMap does not allow null key but allow multiple null values.TreeMap maintains order. It stores keys in sorted and ascending order.LinkedHashMapLinkedHashMap has complexity of O(1) for insertion and lookup.LinkedHashMap allows one null key and multiple null values.LinkedHashMap maintains order in which key-value pairs are inserted.Exampleimport java.util.HashMap; import java.util.Hashtable; import java.util.LinkedHashMap; import java.util.Map; import java.util.TreeMap; public class Tester { ...
Read MoreFormat floating point with Java MessageFormat
To format message with floating point fillers in Java, we use the MessageFormat class. The MessageFormat class gives us a way to produce concatenated messages which are not dependent on the language. The MessageFormat class extends the Serializable and Cloneable interfaces.Declaration −The java.text.MessageFormat class is declared as follows −public class MessageFormat extends FormatThe MessageFormat.format(pattern, params) method formats the message and fills in the missing parts using the objects in the params array matching up the argument numbers and the array indices.The format method has two arguments, a pattern and an array of arguments. The pattern contains placeholder in {} curly ...
Read MoreDifference between x++ and x= x+1 in Java programming
x++ automatically handles the type casting where as x= x + 1 needs typecasting in case of x is not an int variable. See the example below.Examplepublic class Tester { public static void main(String args[]) { byte b = 2; //Type casting is required //as 1 is int and b is byte variable b = (byte) (b + 1); System.out.println(b); byte b1 = 2; //Implcit type casting by the compiler b1++; System.out.println(b1); } }Output3 3
Read MoreConvert Java String Object to Boolean Object
A string object can be created in Java using the string literal.String myStr = “Amit”;Another way to create a string object is using the new keyword.String myStr = new String("Hello!");We have used the first method to create a string object.String str = "true";Now, use the valueOf() method to convert String Object to Boolean Object. We have used this method on Boolean object.Boolean bool = Boolean.valueOf(str);Let us now see the complete example to show how to convert String Object to Boolean Object.Examplepublic class Demo { public static void main(String[] args) { String str = "true"; ...
Read MoreCreate a Boolean object from Boolean value in Java
To create a Boolean object from Boolean value is quite easy. Create an object with Boolean and set the Boolean value “true” or “false”, which are the Boolean literals.Let us now see how “true” value is added.Boolean bool = new Boolean("true");In the same way, “False” value is added.Boolean bool = new Boolean("false");The following is an example displaying how to create a Boolean object from Boolean value.Examplepublic class Demo { public static void main(String[] args) { Boolean bool = new Boolean("true"); System.out.println(bool); bool = new Boolean("false"); System.out.println(bool); } }OutputTrue False
Read MoreGet week of month and year using Java Calendar
For using Calendar class, import the following package.import java.util.Calendar;Create a Calendar class object.Calendar cal = Calendar.getInstance();Now, get the week of month and year using the following fields.Calendar.WEEK_OF_MONTH Calendar.WEEK_OF_YEARThe following is an example.Exampleimport java.util.Calendar; public class Demo { public static void main(String[] args) { Calendar cal = Calendar.getInstance(); // current date and time System.out.println(cal.getTime().toString()); // date information System.out.println("Date Information.........."); System.out.println("Year = " + cal.get(Calendar.YEAR)); System.out.println("Month = " + (cal.get(Calendar.MONTH) + 1)); System.out.println("Date = " + cal.get(Calendar.DATE)); ...
Read MoreFormat hour in k (1-24) format in Java
The “k” format in Java Date is used to format hour in 1-24 format. Use SimpleDateFormat("k") to get the same format.// displaying hour in k format simpleformat = new SimpleDateFormat("k"); String strHour = simpleformat.format(new Date()); System.out.println("Hour in k format = "+strHour);Above, we have used the SimpleDateFormat class, therefore the following package is imported.import java.text.SimpleDateFormat;The following is an example −Exampleimport java.text.Format; import java.text.SimpleDateFormat; import java.util.Date; import java.util.Calendar; public class Demo { public static void main(String[] args) throws Exception { // displaying current date and time Calendar ...
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