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Java Articles
Page 406 of 450
Java Program to get minimum value with Comparator
First, declare an integer array and add some elements −Integer arr[] = { 40, 20, 30, 10, 90, 60, 700 };Now, convert the above array to List −List list = Arrays.asList(arr);Now, use Comparator and the reverseOrder() method. Using max() will eventually give you the maximum value, but with reverseOrder() it reverses the result −Comparator comp = Collections.reverseOrder(); System.out.println("Minimum element = "+Collections.max(list, comp));Example Live Demoimport java.util.Arrays; import java.util.Collections; import java.util.Comparator; import java.util.List; public class Demo { @SuppressWarnings("unchecked") public static void main(String args[]) { Integer arr[] = { 40, 20, 30, 10, 90, 60, 700 }; ...
Read MoreJava Program to convert java.util.Date to LocalDate
At first set the date with java.util.Date −java.util.Date date = new Date();Now, convert the date to LocalDate −Instant instant = Instant.ofEpochMilli(date.getTime()); System.out.println("LocalDate = "+LocalDateTime.ofInstant(instant, ZoneId.systemDefault()).toLocalDate());Example Live Demoimport java.time.Instant; import java.time.LocalDateTime; import java.time.ZoneId; import java.util.Date; public class Demo { public static void main(String[] args) { java.util.Date date = new Date(); System.out.println("Date = "+date); Instant instant = Instant.ofEpochMilli(date.getTime()); System.out.println("LocalDate = "+LocalDateTime.ofInstant(instant, ZoneId.systemDefault()).toLocalDate()); } }OutputDate = Thu Apr 18 23:51:06 IST 2019 LocalDate = 2019-04-18
Read MoreJava Program to check if a Float is Infinite or Not a Number(NAN)
To check if a Float is isInfinite, use the isInfinite() method and to check for NAN, use the isNaN() method.Example Live Demopublic class Demo { public static void main(String[] args) { float value1 = (float) 1 / 0; boolean res1 = Float.isInfinite(value1); System.out.println("Checking for isInfinite? = "+res1); float value2 = (float) Math.sqrt(9); boolean res2 = Float.isNaN(value2); System.out.println("Checking for isNan? = "+res2); } }OutputChecking for isInfinite? = true Checking for isNan? = false
Read MoreHow to calculate the possibilities of duplication for random number within a range in Java
To get the duplicate numbers for random numbers in a range, loop through and create two Random class objects −Use nextInt() to get the next number −intrandVal1 = new Random().nextInt(50); intrandVal2 = new Random().nextInt(50);Now, compare both the above numbers −if (randVal1 == randVal2) { System.out.println("Duplicate number = "+randVal1); }All the above is to be done in a loop −for (int i = 1; i
Read MoreHow to display random numbers less than 20 in Java
At first, create a Random class object −Random rand = new Random();Now, create a new array −int num; int arr[] = new int[10];Loop through and set the Random nextInt with 20 as parameter since you want random numbers less than 20 −for (int j = 0; j
Read MoreSet Date value in Java HashMap?
Create a Calendar instance and Date object −Calendar cal = Calendar.getInstance(); Date date = new Date(); cal.setTime(date);Now, create a HashMap and store Date value −LinkedHashMaphashMap = new LinkedHashMap(); hashMap.put("year", cal.get(Calendar.YEAR)); hashMap.put("month", cal.get(Calendar.MONTH)); hashMap.put("day", cal.get(Calendar.DAY_OF_MONTH));Example Live Demoimport java.util.Calendar; import java.util.Date; import java.util.LinkedHashMap; public class Demo { public static void main(String[] argv) { Calendar cal = Calendar.getInstance(); Date date = new Date(); System.out.println("Date = "+date); cal.setTime(date); LinkedHashMaphashMap = new LinkedHashMap(); hashMap.put("year", cal.get(Calendar.YEAR)); hashMap.put("month", cal.get(Calendar.MONTH)); hashMap.put("day", cal.get(Calendar.DAY_OF_MONTH)); ...
Read MoreHow to display numbers in scientific notation in Java?
To display number in scientific notation, create NumberFormat object first −NumberFormat numFormat = newDecimalFormat();Now, let’s say you need to format the minimum value of Integer −int i = Integer.MIN_VALUE; System.out.println(i); numFormat = newDecimalFormat("0.######E0"); System.out.println(numFormat.format(i)); numFormat = newDecimalFormat("0.#####E0"); System.out.println(numFormat.format(i));Above, we have used format() method of the NumberFormat class.Example Live Demoimport java.text.DecimalFormat; import java.text.NumberFormat; public class Demo { public static void main(String args[]) { NumberFormat numFormat = new DecimalFormat(); int i = Integer.MIN_VALUE; System.out.println(i); numFormat = new DecimalFormat("0.######E0"); System.out.println(numFormat.format(i)); numFormat = new DecimalFormat("0.#####E0"); ...
Read MoreHow to extract multiple integers from a String in Java?
Let’s say the following is our string with integer and characters −String str = "(29, 12; 29, ) (45, 67; 78, 80)";Now, to extract integers, we will be using the following pattern −\dWe have set it with Pattern class −Matcher matcher = Pattern.compile("\d+").matcher(str);Example Live Demoimport java.util.ArrayList; import java.util.List; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Demo { public static void main(String[] args) { String str = "(29, 12; 29, ) (45, 67; 78, 80)"; Matcher matcher = Pattern.compile("\d+").matcher(str); Listlist = new ArrayList(); while(matcher.find()) { list.add(Integer.parseInt(matcher.group())); } System.out.println("Integers = "+list); } }OutputIntegers = [29, 12, 29, 45, 67, 78, 80]
Read MoreHow to get the Checksum of a Byte Array in Java?
Create a Byte Array for which you want the Checksum −byte[] arr = "This is it!".getBytes();Now, create a Checksum object −Checksum checksum = new Adler32(); checksum.update(arr, 0, arr.length);The update() above updates the current checksum with the specified array of bytes.Now, get the checksum with getValue() method, which gives the current checksum value.Example Live Demoimport java.util.zip.Adler32; import java.util.zip.Checksum; public class Demo { public static void main(String[] argv) throws Exception { byte[] arr = "This is it!".getBytes(); Checksum checksum = new Adler32(); checksum.update(arr, 0, arr.length); long res = checksum.getValue(); ...
Read MoreJava Program to change a file attribute to writable
Let’s say our file is “input.txt”, which is set read-only −File myFile = new File("input.txt"); myFile.createNewFile(); myFile.setReadOnly();Now, set the above file to writable −myFile.setWritable(true);After that, you can use canWrite() to check whether the file is writable or not.Example Live Demoimport java.io.File; public class Demo { public static void main(String[] args) throws Exception { File myFile = new File("input.txt"); myFile.createNewFile(); myFile.setReadOnly(); if (myFile.canWrite()) { System.out.println("Writable!"); } else { System.out.println("Read only mode!"); } ...
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