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Ans. There can be two different elements with the same hashcode. When two elements have the same hashcode then Java uses the equals to further differentation. So there can be one or two objects depending on the content of the objects. | ||||
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Like Discuss Correct / Improve  java   hashcode   map   hashmap   object reference   advanced Asked in 1 Companies | ||||
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Ans. Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character set uses only 7 bits, it is usually represented as 8 bits. UTF-8 represents characters using 8, 16, and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns. | ||||
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Ans. Java uses Just-In-Time compiler to enable high performance. Just-In-Time compiler is a program that turns Java bytecode into instructions that can be sent directly to the processor. | ||||
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Ans. It will create the file myfile.txt in the current directory. | ||||
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Ans. Inheritance | ||||
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This question can be asked in different variants like performace improvement of an application, improving performance for DB communication etc. | ||||
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Ans. This depends on entirely upon the code type. For example 1.If its just logic, we can try it to short circuit or put the if / switch case with maximum probability in the beginning. 2. Can use faster data structures, for eg - random retrieval instead of sequence / iterator 3. Working with primitive types or even bytes instead of Objects, even though it may result in marginal improvement. 4. If its service call, then service call with bulk load can help 5. If DB Operation, then with use of Indices , Views or using ORM , cache etc. | ||||
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This question was recently asked at 'Ariba'.This question is still unanswered. Can you please provide an answer. | ||||
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Usually asked to entry level software developers. | ||||
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Ans. public static void main(String[] args) { int num1 = 1; int num2 = 2; num1 = num1^num2; num2 = num1^num2; num1 = num1^num2; System.out.print("num1 = " + num1 +", num2 = "+num2); } | ||||
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Like Discuss Correct / Improve  code  coding Asked in 37 Companies basic   frequent | ||||
Very frequently asked. Usually asked with questions related to String. Frequently asked at CTS / Cognizant | ||||
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Ans. Object that can't be changed after instantiation. | ||||
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Like Discuss Correct / Improve  java   oops   immutable  immutability Asked in 27 Companies basic   frequent | ||||
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Ans. private static boolean isPalindrome(String str) { if (str == null) return false; StringBuilder strBuilder = new StringBuilder(str); strBuilder.reverse(); return strBuilder.toString().equals(str); } | ||||
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Like Discuss Correct / Improve  java   string   stringbuilder   stringbuilder   string class   code   palindrome Asked in 38 Companies Basic   frequent | ||||
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Ans. private static String removeChar(String str, char c) { | ||||
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Ans. Since String is immutable, its hashcode is cached at the time of creation and it doesnt need to be calculated again. This makes it a great candidate for key in a Map and its processing is fast than other HashMap key objects. This is why String is mostly used Object as HashMap keys. | ||||
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Like Discuss Correct / Improve  java   string class   string   immutable  immutability   hashmap   immutable  immutability   hashcode   hash code   advanced Asked in 2 Companies expert   frequent | ||||
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Ans. Yes. static method is not accessed by the instance of class. Either you call it by the class name or the reference. | ||||
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Like Discuss Correct / Improve  java   static   static method   code | ||||
Very frequently asked in HCL Tech ( Based of 4 inputs ) | ||||
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Ans. Using String method - new StringBuffer(str).reverse().toString(); Iterative - public static String getReverseString(String str){ StringBuffer strBuffer = new StringBuffer(str.length); for(int counter=str.length -1 ; counter>=0;counter--){ strBuffer.append(str.charAt(counter)); } return strBuffer; } Recursive - public static String getReverseString(String str){ if(str.length <= 1){ return str; } return (getReverseString(str.subString(1)) + str.charAt(0); } | ||||
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Ans. true, due to String Pool, both will point to a same String object. | ||||
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Ans. Compile time error as it won't find the constructor matching BuggyBread2(). Compiler won't provide default no argument constructor as programmer has already defined one constructor. Compiler will treat user defined BuggyBread2() as a method, as return type ( void ) has been specified for that. | ||||
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Ans. Yes. | ||||
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Ans. matcher.find() should have been used instead of matcher.next() within while. | ||||
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Ans. It will print 4567,5678 and 6789 but Order cannot be predicted. | ||||
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Ans. This will give compile time error as we cannot retrieve the element from a specified index using Set. Set doesn't maintain elements in any order. | ||||
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Ans. WEDNESDAY FRIDAY SATURDAY Only one FRIDAY will be printed as Set doesn't allow duplicates.Elements will be printed in the order in which constants are declared in the Enum. TreeSet maintains the elements in the ascending order which is identified by the defined compareTo method. compareTo method in Enum has been defined such that the constant declared later are greater than the constants declared prior. | ||||
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Ans. int findMax(int[] items){ int maxNumber = 0; for(int x:items){ if(x > maxNumber){ maxNumber = x; } } return maxNumber; } | ||||
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Ans. Yes , It can be done using single for loop public class BuggyBread{ public static void main (String args[]) { int x = 50; for(int i=1;i <= 100;i++){ if(i<=50){ System.out.println(i*2); } else { System.out.println(i-x); x = x - 1; } } } } | ||||
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Ans. import java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.io.*; public class Common { public static void main(String ar[])throws Exception { File f=new File("a.txt"); File f1=new File("x.java"); System.out.println(f.exists()); FileInputStream fin = new FileInputStream(f); FileInputStream fin1 = new FileInputStream(f1); byte b[]=new byte[10000]; byte b1[]=new byte[10000]; fin.read(b); fin1.read(b1); String s1 = new String(b); String s2 =new String(b1); String words1[] = s1.trim().split(" "); String words2[] = s2.trim().split(" "); Listlist1 = new ArrayList<>(Arrays.asList(words1)); Listlist2 = new ArrayList<>(Arrays.asList(words2)); list1.retainAll(list2); System.out.println(list1); } } | ||||
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Ans. int duplicateArray[] = { 1, 2, 2, 3, 4, 5, 6, 8, 9} Set unique = new HashSet(); for (int i = 0; i < duplicateArray.length; i) { if (unique.contains(duplicateArray[i])) { System.out.println(duplicateArray[i]); } else { unique.add(duplicateArray[i]); } } Complexity O(n) = nHashSet contains and add has O(n) = 1 | ||||
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Ans. private void permutation(String prefix, String sufix) { int ln = sufix.length(); if(ln == 0) { System.out.println(prefix); } else { IntStream.range(0, ln).forEach(i->permutation(prefix sufix.charAt(i), sufix.substring(0,i) sufix.substring(i 1, ln))); } } call:permutation("", "abcdef"); | ||||
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Ans. File folder = new File(path); if(!folder.exists()){ try { folder.mkdir(); } catch (Exception e) {} } | ||||
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Ans. Unreachable code is a code segment that can never be executed in any case. For example - int x = 5; return; System.out.println(x); In this code , 2nd line will return the control out of the method and hence 3rd line will never get executed and hence is unreachable code. This will be caught at compile time only. | ||||
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Ans. Code segment. | ||||
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Like Discuss Correct / Improve  memory   java   memory management   code segment  code segment memory expert   rare | ||||
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Ans. A way of encoding characters as binary numbers. The Unicode character set includes characters used in many languages, not just English. Unicode is the character set that is used internally by Java. | ||||
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