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Q761. Write a Program to check if a number is perfect or not

Ans. public class BuggyBread {
   public static void main(String args[]) {
       int number = 7;
       boolean perfectNumber = true;
       for(int x=2;x<number;x++){
          if(number % x == 0){
             perfectNumber = false;
          }
       }

       if(perfectNumber){
          System.out.println("Perfect Number");
       } else {
          System.out.println("Not a Perfect Number");
       }
   }
}

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Q762. What are the different operators in Java ?

Ans. && - AND
|| - OR
! - LOGICAL NOT

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Q763. What are the different primitive data types in Java ?

Ans. boolean
byte
char
double
float
int
long
short
void

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Q764. What are the ways to Reuse Code in Java ?

Ans. 1. Object Level Reuse - private methods
2. Class Level Reuse - static methods
3. package level Reuse - default methods
4. Application Level Reuse - Classes
5. Multiple Applications Level Reuse - Libraries , Frameworks

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Q765. Write a Program to remove multiple spaces

For example

We are what we repeatedly do; excellence, then, is not an act but a habit

should result in

We are what we repeatedly do; excellence, then, is not an act but a habit

Ans. public class BuggyBread {
   public static void main(String args[]) {
      String str = "We are what we repeatedly do; excellence, then, is not an act but a habit";

      String[] splittedString = str.split(" ");

      for(String word: splittedString){
         word = word.trim();
         if(!word.equals("")){
            System.out.print(word.trim());
            System.out.print(" ");
         }
      }


   }
}

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Q766. Write a Program to remove all spaces in a String

Ans. public class BuggyBread {
   public static void main(String args[]) {

      String str = "We are what we repeatedly do; excellence, then, is not an act but a habit";

      System.out.println(str.replaceAll(" ", ""));
   }
}

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Q767. Write a Program to Sort entries of a map by its value

Ans. public class BuggyBread {
   public static void main(String args[]) {
      Map<String,Integer> wordLength = new HashMap();

      String str = "We are what we repeatedly do; excellence, then, is not an act but a habit";

      for(String word: str.split(" ")){
            wordLength.put(word, word.length());
      }

      List<Map.Entry<String, Integer>> list = new LinkedList<Map.Entry<String, Integer>>( wordLength.entrySet() );

      Collections.sort( list, new Comparator<Map.Entry<String, Integer>>()
{
public int compare( Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2 )
{
return (o1.getValue()).compareTo( o2.getValue() ) * -1;
}
} );

      System.out.println(list);

   }
}

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Q768. Write a Program to print 3 largest words in a String

Ans. public class BuggyBread {
public static void main(String args[]) {
Map<String,Integer> wordLength = new HashMap();

String str = "We are what we repeatedly do; excellence, then, is not an act but a habit";

str = str.replaceAll(",","");
str = str.replaceAll(";","");
str = str.toLowerCase();

for(String word: str.split(" ")){
wordLength.put(word, word.length());
}

List<Map.Entry<String, Integer>> list = new LinkedList<Map.Entry<String, Integer>>( wordLength.entrySet() );

Collections.sort( list, new Comparator<Map.Entry<String, Integer>>()
{
public int compare( Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2 )
{
return (o1.getValue()).compareTo( o2.getValue() ) * -1;
}
} );

int countWords = 1;

for(Map.Entry<String, Integer> entry:list){
if(countWords <= 3){
System.out.println(entry.getKey());
}

countWords++;

}
}
}

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Q769. Write a Program to print 3 smallest words in a String

Ans. public class BuggyBread {
   public static void main(String args[]) {
      Map<String,Integer> wordLength = new HashMap();

      String str = "We are what we repeatedly do; excellence, then, is not an act but a habit";

      str = str.replaceAll(",","");
      str = str.replaceAll(";","");
      str = str.toLowerCase();

      for(String word: str.split(" ")){
            wordLength.put(word, word.length());
      }

      List<Map.Entry<String, Integer>> list = new LinkedList<Map.Entry<String, Integer>>( wordLength.entrySet() );

      Collections.sort( list, new Comparator<Map.Entry<String, Integer>>()
{
public int compare( Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2 )
{
return (o1.getValue()).compareTo( o2.getValue() );
}
} );

      int countWords = 1;

      for(Map.Entry<String, Integer> entry:list){
         if(countWords <= 3){
            System.out.println(entry.getKey());
         }

         countWords++;

      }
   }
}

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Q770. Write a Program that prints words longer than 5 characters in a String

For example

We are what we repeatedly do; excellence, then, is not an act but a habit

should print

repeatedly
excellence

Ans. public class BuggyBread1 {
   public static void main(String args[]) {
      Map<String,Integer> wordLength = new HashMap();

      String str = "We are what we repeatedly do; excellence, then, is not an act but a habit";
      String longestWord = "";

      str = str.replaceAll(",","");
      str = str.replaceAll(";","");
      str = str.toLowerCase();

      for(String word: str.split(" ")){
            wordLength.put(word, word.length());
      }

      for(Map.Entry<String, Integer> entry:wordLength.entrySet()){
         if(entry.getValue().intValue() > 5){
            System.out.println(entry.getKey());
         }
      }
   }
}

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Q771. Write a Program that prints the repeated words in a String

For example -

We are what we repeatedly do; excellence, then, is not an act but a habit.

should print we, should count for case insensitive words too

Ans. public class BuggyBread {
   public static void main(String args[]) {
      Map<String,Integer> wordLength = new HashMap();

      String str = "We are what we repeatedly do; excellence, then, is not an act but a habit.";
      String longestWord = "";

      str = str.replaceAll(",","");
      str = str.replaceAll(";","");
      str = str.replaceAll("/.","");
      str = str.toLowerCase();

      for(String word: str.split(" ")){
         if(wordLength.containsKey(word)){
            wordLength.put(word, wordLength.get(word).intValue() + 1);
         } else {
            wordLength.put(word, 1);
         }
      }

      for(Map.Entry<String, Integer> entry:wordLength.entrySet()){
         if(entry.getValue().intValue() > 1){
            System.out.println(entry.getKey());
         }
      }
   }
}

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Q772. Write a Program to find the longest word in a string

Ans. public class BuggyBread {
   public static void main(String args[]) {
      String str = "We are what we repeatedly do; excellence, then, is not an act but a habit.";
      String longestWord = "";

      str = str.replaceAll(",","");
      str = str.replaceAll(";","");
      str = str.replaceAll("/.","");

      for(String word: str.split(" ")){
         if(word.length() > longestWord.length()){
            longestWord = word;
         }
      }

      System.out.println(longestWord);
   }
}

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Q773. Given two files with list of words, write a program to show the common words in both files

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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Q774. Write a Program / Code showing Inheritance and overridding

Ans. class A {
public void test() {
System.out.println("Class A Test");
}
}

class B extends A {
public void test() {
System.out.println("Class B Test");
}

public static void main(String[] args){
A a = new B();
a.test(); // will print Class B Test
}
}

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Q775. Write Code showing Inheritance

Ans. class A {
public void test() {
System.out.println("Class A Test");
}
}

class B extends A {
public void test() {
System.out.println("Class B Test");
}
}

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Q776. Write a program to print two digit numbers that fulfil following criteria

Summing their digits and then multiplying with 3 should result in the number

For ex - 27 , (2+7) * 3 = 27

Ans. public class BuggyBread {
   public static void main(String args[]) {
      for(int x=10;x<100;x++){
         int tensDigit = x/10;
         int unitDigit = x%10;

         if((tensDigit+unitDigit)*3 == x){
            System.out.println(x);
         }
      }
   }
}

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Q777. Given a sorted array, write a program to check if two elements sum up to third.

^{This question was recently asked at 'Facebook'.This question is still unanswered. Can you please provide an answer.}

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Q778. Write a Program to print series like

1
12
123
1234
12345

till 100

Ans. public class BuggyBread{
public static void main (String args[]) {
   for(int x=1;x<=100;x++){
      for(int y=1;y <= x;y++){
         System.out.print(y);
      }
      System.out.println("
");
   }
}
}

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Q779. Write a Program to print 1 (1 time) , 2 ( 2 times ) and so on till 100.

Ans. public class BuggyBread1{
public static void main (String args[]) {
   for(int x=1;x<=100;x++){
      for(int y=1;y <= x;y++){
         System.out.println(x);
      }
   }
}
}

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Q780. Write a Program to print all numbers till 100 that are divisible by 5

Ans. public class BuggyBread{
public static void main (String args[]) {
   for(int counter=1;counter<=100;counter++){
      if(counter % 5 == 0){
         System.out.println(counter);
      }
   }
}
}

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Q781. Write a Program to only print characters that have occured more than once in a String

Ans. public class BuggyBread{
public static void main (String args[]) {
Set<Character> set = new HashSet();
Set<Character> setWithDuplicateChar = new HashSet();
String str = "hello world";
for(char character: str.toCharArray()){
if(set.contains(character)){
setWithDuplicateChar.add(character);
} else {
set.add(character);
}
}

System.out.println(setWithDuplicateChar);
}
}

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Q782. Write a Program to print count of each character in a String.

Ans. public class BuggyBread {
public static void main(String args[]) {
Map<Character, Integer> countMap = new HashMap();
String str = "hello world";
for (char character : str.toCharArray()) {
if (countMap.containsKey(character)) {
countMap.put(character, countMap.get(character) + 1);
} else {
countMap.put(character, 1);
}
}
System.out.println(countMap);
}
}

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Q783. Write a program to print the index of the first non repeated character in a java string

Ans. public class BuggyBread1{
public static void main (String args[]) {
   String str = "hheello world";
   char[] charArray = str.toCharArray();
   char selectedChar = 'a';
   for(char char1: charArray){
      if(!str.contains(Character.toString(char1).concat(Character.toString(char1)))){
         selectedChar = char1;
         break;
      }
   }
   System.out.println(str.indexOf(Character.toString(selectedChar)));
}
}

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Q784. Write a program to print all even numbers first and then all odd numbers till 100. For example the output should be
2
4
6
8
...... 100
and then
1
3
5
7
...... 99

using only 1 for loop ? Is it possible with just one loop ?

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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Q785. Write a program in Java that prints the numbers from 1 to 100. But for multiples of three print Fizz instead of the number and for the multiples of five print Buz. For numbers which are multiples of both three and five print FizzBuzz

Ans. public class Class{
public static void main(String[] args){
for(int i=1;i<= 100;i++){
if(i%3 == 0){
if(i%5 == 0){
System.out.println("FizzBuzz");
}
System.out.println("Fizz");
} else if(i%5 == 0){
System.out.println("Buzz");
} else {
System.out.println(i);
}

}
}
}

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Q786. Write a Program to check if string is a Colidrome ?
(Colidrome is a word that has n alphabets followed by the reverse of the n alphabets, for ex - mallom)

Ans.
public class Class {
   public static void main(String[] args) {
      String str = "mallam";
      String firstHalf = str.substring(0, str.length() / 2);
      String secondHalf = str.substring(str.length() / 2);

      if (firstHalf.equals(new StringBuilder(secondHalf).reverse().toString())) {
         System.out.println("It's a Colidrome");
      } else {
         System.out.println("It's not a Colidrome");
      }
   }
}

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Q787. Write a Program to check number of occurrences of one string within another ?

Ans. public class Class{
   public static void main(String[] args){
      String string1 = "Hello I am Jack. I live in United States. I live in california state.";

      String string2 = "I live in";

      int startIndex = 0;
      int endIndex = string1.length()-1;

      int countNoOfOccurences = 0;

      String remainingString = string1;

      while(startIndex < endIndex){
         if(remainingString.indexOf(string2) != -1){
            countNoOfOccurences++;
            startIndex = remainingString.indexOf(string2) + string2.length();
            remainingString = remainingString.substring(startIndex);
         } else {
            break;
         }
      }

      System.out.println(countNoOfOccurences);
   }
}

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Q788. Write a program to check is a string is substring of another ?

Ans. public class Class{
   public static void main(String[] args){
      String string1 = "Hello I am Jack. I live in United States. I live in california state.";

      String string2 = "I live in";

      if(string1.indexOf(string2) >= -1){
         System.out.println("string2 is sub string of string1");
      } else {
         System.out.println("string2 is not sub string of string1");
      }
   }
}

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Q789. Write a class / program that takes few numbers from the input and then output the average ?

Ans. public class Class{
   public static void main(String[] args){
      List<Integer> collector = new ArrayList();

      Scanner scanner = new Scanner(System.in);
      int x = scanner.nextInt();
      while(x != 0){
         collector.add(x);
         x = scanner.nextInt();
      }
      System.out.println(collector.stream().collect(Collectors.averagingInt(p->((Integer)p))));
   }
}

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Q790. What is the difference between compilation and decompilation ?

Ans. Compilation is the process of converting Java source files to class files which can be executed by the Java runtime environment whereas Decompilation is the process of converting class files back to the Java Source code.

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