Core Java - Interview Questions and Answers for 'Coding' | Search Interview Question

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Q101. Given a string with multiple opening and closing brackets, determine if the string is valid or not ( to see if the string has all closing brackets for each opening bracket ) ?

Core Java

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Q102. Write a method, that compare two numbers and return the bigger one ?

Core Java

Ans. int compare(int a, int b) {
a>b? return a: return b;
}

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Q103. Write a Program for insertion sort.

Core Java

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Q104. How to calculate lcm of two numbers ?

Core Java

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Q105. Write a Program to find age by birth date ?

Core Java

Ans. LocalDate today = LocalDate.now();
LocalDate birthday = LocalDate.of(1960, Month.JANUARY, 1);
Period p = Period.between(birthday, today); //Now access the values as below
System.out.println(period.getDays());
System.out.println(period.getMonths());
System.out.println(period.getYears());

Sample Code for LocalDate

Sample Code for Period

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Q106. What will be the output of following code

class TestMain {
public static void main(String[] args) {
String s1 = "ravi";
String s2 = new String("ravi");
Integer i = 10;
Integer a1 = new Integer("10");
System.out.println(s1 == s1);
System.out.println(i == a1);
}
}

Core Java

Ans. false
false

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Q107. Write a Program to check if the entered number is a Duck Number ( Number having 0 in it ) ?

Core Java

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Q108. Suppose we have a string "Java is object oriented language" and we have to reverse every alternate word in string. How would we do that using Java program.

Core Java

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Q109. A Kid can go up 1, 2 or 3 stairs in one step. Write a method that takes number of steps in a stair will print all possible ways he can take.

For example , printAllCombinations(3) should print

111
12
21
3

Similarly , printAllCombinations(4) should print

1111
121
13
211
22
31
4

Core Java

Ans. public static String findStep(int n) {
if (n == 1 || n == 0)
return 1;
else if (n == 2)
return 2;
else
return findStep(n - 3) + findStep(n - 2) + findStep(n - 1);
}

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Q110. Write an efficient program for printing k largest elements in an array. Elements in array can be in any order.

Data Structure

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Q111. Create a custom hashmap using synchronization.

Core Java

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Q112. Write a Program to find number of lines , words and characters in a File.

Core Java

Ans. import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class FileUtility {

public static void main(String[] args) {
System.out.println(printFile("/home/userme/notes"));
}

private static int printFile(String filePath) {
int wordCount = 0;
try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
String line = null;
String[] wordsArray = null;

while ((line = br.readLine()) != null) {
wordsArray = line.split(" ");
wordCount = wordsArray.length;
}
} catch (IOException e) {
e.printStackTrace();
}
return wordCount;

}
}

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Q113. Write code to get count of every 5 letter word in a string using lambda expression

Core Java

Ans. String str = "I had been saying that he had been there";

Map<String,Long> countWords = Arrays.asList(str.split(" ")).stream().filter(p->p.length() = 5).collect(Collectors.groupingBy(p->p,Collectors.counting()));

System.out.println(countWords);

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Q114. Find Intersection/union between two arrays.

Core Java

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Q115. Design a Program to clone an object and all it's children.

Design

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Q116. Given a String with letters , numbers and special characters , extract Tokens from it. The rules for Token extraction are ac follows

1. Should for token of all characters till a number or special character is found
2. Should form token of all numbers till a character or special character is found
3. Special character in itself is a token
4. Ignore white spaces

For example - Bob Said "He is here"

should result in

Bob A
Said A
" S
He A
is A
here A
" S

where a is specifying alphabet and S as special character

Design

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Q117. How many bytes a character takes with UTF-8 encoding ?

Encoding

Ans. it takes 1 to 4 bytes

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Q118. How to calculate string length without using inbuilt function

Core Java

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Q119. in the following class:
class A {
void methoda(Object o) {
Sysout("Object");
}

void methoda(String s) {
Sysout("String");
}

public static void main(String []args) {
A a = new A();
a.methoda(null);
}
}

what will be printed?

Core Java

Ans. String

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Q120. Can you share your experience with encoding and encryption ?

Encoding

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Q121. What is the difference between html encoding and url encoding ?

Encoding

Ans. HTML Encoding escapes special characters in strings used in HTML documents whereas url Encoding replaces special characters with characters so that they can sent within url.

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Q122. Does spaces get's encoded in html encoding ?

Encoding

Ans. Yes they get html encoded. i.e   instead of empty space.

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Q123. What will be the output of following code ?

public class BuggyBread {

   private int x;

   private BuggyBread(int x){
      x = x;
   };

   public static void main(String[] args){
      BuggyBread buggybread = new BuggyBread(5);
      System.out.println(buggybread.x);
   }
}

Core Java

a. compilation error

b. undefined

c. 0

d. 5

Ans.c. 0

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