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Core Java - Interview Questions and Answers for 'Coding' - 122 question(s) found - Order By Rating

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Q1. Does spaces get's encoded in html encoding ?

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

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Q2. What is the difference between html encoding and url 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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Q3. Can you share your experience with encoding and encryption ?

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Q4. 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?

Ans. String

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Q5. Write code to create a folder if it doesn't exist.

Ans. File folder = new File(path);

if(!folder.exists()){
try {
folder.mkdir();

} catch (Exception e) {}
}

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Q6. How to calculate string length without using inbuilt function

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Q7. How many bytes a character takes with UTF-8 encoding ?

Ans. it takes 1 to 4 bytes

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Q8. 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

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Q9. Design a Program to clone an object and all it's children.

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Q10. Find Intersection/union between two arrays.

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Q11. Write code to get count of every 5 letter word in a string using lambda expression

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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Q12. Write a Program to find number of lines , words and characters in a File.

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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Q13. Find different combination of given String and trace the output

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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Q14. Create a custom hashmap using synchronization.

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Q15. Write an efficient program for printing k largest elements in an array. Elements in array can be in any order.

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Q16. 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

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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Q17. 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.

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Q18. Write a Program to check if the entered number is a Duck Number ( Number having 0 in it ) ?

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Q19. 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);
}
}

Ans. false
false

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Q20. Write code to find second largest number in an array of integers.

Ans. int arr[]={1,3,5,6,4,8,9,2,10};
Arrays.sort();
System.out.println(arr[arr.length-1]);

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Q21. Write a Program to find age by birth date ?

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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Q22. How to calculate lcm of two numbers ?

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Q23. Write a Program for insertion sort.

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Q24. Write a method, that compare two numbers and return the bigger one ?

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

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Q25. 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 ) ?

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Q26. Write a Program to convert a binary to number ?

Ans. int convert(int binaryInt) {
int sumValue=0;
int multiple = 1;
while(binaryInt > 0) {
binaryDigit = binaryInt;
binaryInt = binaryInt /10;
sumValue = sumValue (binaryDigit * multiple);
multiple = multiple * 2;
}

return sumValue;
}

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Q27. How can you extract integers from string values and add (sum it up) all the extracted integers? e.g "James34long4island322in3rdAvenue" ---> 34 4 322 3 = 363

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Q28. Implement stack using generics in Java.

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Q29. Write a program for 0 and cross games?

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Q30. Write a program to reverse words of a sentence.

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