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Programming Articles
Page 2381 of 2547
Removal of negative numbers from an array in Java
Following program shows how to remove negative numbers from an array.Exampleimport java.util.ArrayList; import java.util.Iterator; import java.util.List; public class Tester { public static void main(String[] args) { List objArray = new ArrayList(); objArray.clear(); objArray.add(2); objArray.add(-3); objArray.add(4); System.out.println("Array before removing an element "+objArray); Iterator iterator = objArray.iterator(); while(iterator.hasNext()) { Integer next = iterator.next(); if(next < 0) { iterator.remove(); } } System.out.println("Array after removing an element"+objArray); } }OutputArray before removing an element [ 2, -3, 4 ] Array after removing an element [ 2, 4 ]
Read Morehow can I declare an Object Array in Java?
Array of Object class can be created which can accept any type of object. During operation on such array, instanceof operator can be used.Examplepublic class Tester { public static void main(String[] args) { Object[] dataArray = new Object[3]; dataArray[0] = new Integer(0); dataArray[1] = new String("1"); dataArray[2] = new Boolean(false); for(Object data: dataArray) { if(data instanceof Integer) { System.out.println(((Integer) data).intValue()); } if(data instanceof String) { System.out.println(data); } if(data instanceof Boolean) { System.out.println(((Boolean) data).booleanValue()); } } } }Output0 1 false
Read MoreHow do you find the sum of all the numbers in a java array
Following program print the sum of the all the numbers in an array.Examplepublic class Tester { public static void main(String[] args) { int[] dataArray = {1, 2, 3, 4}; int sum = 0; for(int i: dataArray) { sum += i; } System.out.println(sum); } }Output10
Read MoreHow to convert a String to and fro from UTF8 byte array
Following example will showcase conversion of a Unicode String to UTF8 byte[] and UTF8 byte[] to Unicode byte[] using Reader and Writer classes.ExampleIOTester.javaimport java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.io.Reader; import java.io.Writer; import java.nio.charset.Charset; import java.text.ParseException; public class I18NTester { public static void main(String[] args) throws ParseException, IOException { String input = "This is a sample text" ; InputStream inputStream = new ByteArrayInputStream(input.getBytes()); //get the UTF-8 data Reader reader = new InputStreamReader(inputStream, Charset.forName("UTF-8")); ...
Read MoreHow do I reverse an int array in Java
Following program reverses an int array.Examplepublic class Tester { public static void main(String[] args) { int[] numbers = {1,2,3,4,5}; //swap the numbers till the midpoint comes for (int start = 0, end = numbers.length - 1; start
Read MoreWhy is char[] preferred over String for storing passwords?
Yes, Storing password in String object is not safe for following reasons −String objects are immutable and until garbage collected, they remain in memory.String being plain text can be tracked in memory dump of the application.In log, String based password may be printed which can cause a problem.Char[] can be cleared or wiped out after the job is done.
Read MoreConverting ArrayList to String[] in java
Following program is converting an ArrayList to String[];Exampleimport java.util.ArrayList; import java.util.List; public class Tester { public static void main(String[] args) { List names = new ArrayList(); names.add("A"); names.add("B"); names.add("C"); String[] nameArray = names.toArray(new String[names.size()]); for(String name: nameArray) { System.out.println(name); } } }OutputA B C
Read MoreConvert bytes to a string in java
Use String(byte[]) constructor to convert byte[] to String.Examplepublic class Tester { public static void main(String[] args) { String test = "I love learning Java"; byte[] bytes = test.getBytes(); String converted = new String(bytes); System.out.println(converted); } }OutputI love learning Java
Read MoreThe most elegant ways to iterate the words of a java string.
Just split the string based on space and then iterate it. See the example below −Examplepublic class Tester { public static void main(String[] args) { String test = "I love learning Java"; String[] subStrings = test.split(" "); for(String subString: subStrings) { System.out.println(subString); } } }OutputI love learning Java
Read MoreWhy use Java annotations?
Annotations provide information about java elements. Annotations can be interpreted by compiler or IDE at compile time or by JVM at runtime. Annotations can be usedto show attributes of an element: e.g. @Deprecated, @Override, or @NotNullto describe the purpose of an element of the framework, e.g. @Entity, @TestCase, @WebServiceto describe the behavior of an element: @Statefull, @TransactionBefore Java 5, XML was primarily used to store information about java objects, with annotations, this information can be stored within the java code itself.
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