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Java Articles
Page 311 of 450
Floating point operators and associativity in Java
Following programs shows the float arithmetic can cause dubious result if integer values are used using float variables.Examplepublic class Tester { public static void main(String[] args) { float a = 500000000; float b = -500000000; float c = 1; float sumabc1 = a+(b+c); float sumabc2 =(a+b)+c; System.out.println("Floating Point Arithmetic"); System.out.println("a + ( b + c ) : " + sumabc1); System.out.println("(a + b) + c : " + sumabc2); ...
Read MoreFloating point operators and associativity in Java
Following programs shows the float arithmetic can cause dubious result if integer values are used using float variables.Examplepublic class Tester { public static void main(String[] args) { float a = 500000000; float b = -500000000; float c = 1; float sumabc1 = a+(b+c); float sumabc2 =(a+b)+c; System.out.println("Floating Point Arithmetic"); System.out.println("a + ( b + c ) : " + sumabc1); System.out.println("(a + b) + c : " + sumabc2); ...
Read MoreWhy we should use whole string in Java regular expression
In Java regex matches() matches the input string against the whole string as it add a ^ and $ at the end of the input string.so it will not match the substring. So for matching substring, you should use find().Exampleimport java.util.regex.*; class PatternMatchingExample { public static void main(String args[]) { String content = "aabbcc"; String string = "aa"; Pattern p = Pattern.compile(string); Matcher m = p.matcher(content); System.out.println(" 'aa' Match:"+ m.matches()); System.out.println(" 'aa' Match:"+ m.find()); } }Output'aa' Match:false 'aa' Match:true
Read MoreFactory method to create Immutable Map in Java SE 9
With Java 9, new factory methods are added to Map interface to create immutable instances. These factory methods are convenience factory methods to create a collection in less verbose and in concise way.Old way to create collectionsExampleimport java.util.Collections; import java.util.HashMap; import java.util.Map; public class Tester { public static void main(String []args) { Map map = new HashMap(); map.put("A", "Apple"); map.put("B", "Boy"); map.put("C", "Cat"); Map readOnlyMap = Collections.unmodifiableMap(map); System.out.println(readOnlyMap); try { readOnlyMap.remove(0); ...
Read MoreFactory method to create Immutable Map in Java SE 9
With Java 9, new factory methods are added to Map interface to create immutable instances. These factory methods are convenience factory methods to create a collection in less verbose and in concise way.Old way to create collectionsExampleimport java.util.Collections; import java.util.HashMap; import java.util.Map; public class Tester { public static void main(String []args) { Map map = new HashMap(); map.put("A", "Apple"); map.put("B", "Boy"); map.put("C", "Cat"); Map readOnlyMap = Collections.unmodifiableMap(map); System.out.println(readOnlyMap); try { readOnlyMap.remove(0); ...
Read MoreExternalizable Interface in Java
Externalization is used whenever we need to customize serialization mechanism. If a class implements an Externalizable interface then, object serialization will be done using writeExternal() method. Whereas at receiver's end when an Externalizable object is a reconstructed instance will be created using no argument constructor and then the readExternal() method is called.If a class implements only Serializable interface object serialization will be done using ObjectoutputStream. At the receiver's end, the serializable object is reconstructed using ObjectInputStream.Below example showcases usage of Externalizable interface.Exampleimport java.io.Externalizable; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInput; import java.io.ObjectInputStream; import java.io.ObjectOutput; import java.io.ObjectOutputStream; public class ...
Read MoreExternalizable Interface in Java
Externalization is used whenever we need to customize serialization mechanism. If a class implements an Externalizable interface then, object serialization will be done using writeExternal() method. Whereas at receiver's end when an Externalizable object is a reconstructed instance will be created using no argument constructor and then the readExternal() method is called.If a class implements only Serializable interface object serialization will be done using ObjectoutputStream. At the receiver's end, the serializable object is reconstructed using ObjectInputStream.Below example showcases usage of Externalizable interface.Exampleimport java.io.Externalizable; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInput; import java.io.ObjectInputStream; import java.io.ObjectOutput; import java.io.ObjectOutputStream; public class ...
Read MoreDouble brace initialization in Java
Double braces can be used to create and initialize objects in a single Java expression. See the example below −Exampleimport java.util.ArrayList; import java.util.List; public class Tester{ public static void main(String args[]) { List list = new ArrayList(); list.add("A"); list.add("B"); list.add("C"); list.add("D"); list.add("E"); list.add("F"); System.out.println(list); List list1 = new ArrayList() { { add("A"); add("B");add("C"); add("D");add("E");add("F"); ...
Read MoreDouble brace initialization in Java
Double braces can be used to create and initialize objects in a single Java expression. See the example below −Exampleimport java.util.ArrayList; import java.util.List; public class Tester{ public static void main(String args[]) { List list = new ArrayList(); list.add("A"); list.add("B"); list.add("C"); list.add("D"); list.add("E"); list.add("F"); System.out.println(list); List list1 = new ArrayList() { { add("A"); add("B");add("C"); add("D");add("E");add("F"); ...
Read MoreDo we need forward declarations in Java?
Forward declarations means the declaration of a method or variable prior to its implementation. Such declaration is necessary in C/C++ programming language in order to be able to use a variable or object before its implementation. In case, if we want to use a library code, then we need to create its header file and use it. But this is not a case in Java.Java allows using a variable, class prior to its declaration and implementation.Java allows using libraries code without any need of header files.Following example showcases the same. Here we have used a class object before its declaration.Examplepublic ...
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