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 Q331. Difference between throw and throws ?Core Java
Ans. throw is used to explicitly throw an exception especially custom exceptions, whereas throws is used to declare that the method can throw an exception.

We cannot throw multiple exceptions using throw statement but we can declare that a method can throw multiple exceptions using throws and comma separator.

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 Q332. Can we use "this" within static method ? Why ?Core Java
Ans. No. Even though "this" would mean a reference to current object id the method gets called using object reference but "this" would mean an ambiguity if the same static method gets called using Class name.

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 Q333. What are the platforms supported by Java Programming Language?Core Java
Ans. Java runs on a variety of platforms, such as Windows, Mac OS, and the various versions of UNIX/Linux like HP-Unix, Sun Solaris, Redhat Linux, Ubuntu, CentOS, etc

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 Q334. What is an Object ?Core Java
Ans. Object is a run time entity whose state is stored in fields and behavior is shown via methods. Methods operate on an object's internal state and serve as the primary mechanism for object-to-object communication.

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 Q335. What is a Class ?Core Java
Ans. A class is a blue print or Mold using which individual objects are created. A class can contain fields and methods to describe the behavior of an object.

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 Q336. What data type Variable can be used in a switch statement ?Core Java
Ans. Variables used in a switch statement can only be a byte, short, int, or char ( and String with Java 7 and above )

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 Q337. What are the sub classes of Exception class?Core Java
Ans. The Exception class has two main subclasses : IOException class and RuntimeException Class.

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 Q338. How finally used under Exception Handling?Core Java
Ans. The finally keyword is used to create a block of code that follows a try block. A finally block of code always executes, whether or not an exception has occurred.

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 Q339. Explain Set Interface?Core Java
Ans. It is a collection of element which cannot contain duplicate elements. The Set interface contains only methods inherited from Collection and adds the restriction that duplicate elements are prohibited.

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 Q340. What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?Core Java
Ans. The Reader/Writer class hierarchy is character-oriented, and the InputStream/OutputStream class hierarchy is byte-oriented

  Sample Code for InputStream

  Sample Code for OutputStream

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 Q341. Which Java operator is right associative?Core Java
Ans. The = operator is right associative.

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 Q342. What is the difference between a break statement and a continue statement?Core Java
Ans. Break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to the loop statement.

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 Q343. What is the purpose of the System class?Core Java
Ans. The purpose of the System class is to provide access to system resources.

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 Q344. Variable of the boolean type is automatically initialized as?Core Java
Ans. The default value of the boolean type is false.

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 Q345. Can try statements be nested?Core Java
Ans. Yes

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 Q346. What is the difference between the size and capacity of a Vector?Core Java
Ans. The size is the number of elements actually stored in the vector, while capacity is the maximum number of elements it can store at a given instance of time.

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 Q347. What is an enumeration?Core Java
Ans. An enumeration is an interface containing methods for accessing the underlying data structure from which the enumeration is obtained. It allows sequential access to all the elements stored in the collection.

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 Q348. In a case where there are no instance variables what does the default constructor initialize?Core Java
Ans. Java expects the superclass ( Object Class ) constructor to be called while creation of any object. So super constructor is called in case there are no instance variables to initialize.

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 Q349. How do you check memory leak in Java?Core Java
Ans. You need to capture heap dump when it's in the healthy state. Start your application. Let it take real traffic for 10 minutes. At this point, capture heap dump. Heap Dump is basically the snapshot of your memory. It contains all objects that are residing in the memory, values stored in those objects, inbound

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 Q350. Write a program to print the index of the first non repeated character in a java stringCore Java
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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 Q351. Which String class methods are used to make string upper case or lower case?Core Java
Ans. toUpperCase and toLowerCase

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 Q352. How to convert String to byte array and vice versa?Core Java
Ans. We can use String getBytes() method to convert String to byte array and we can use String constructor new String(byte[] arr) to convert byte array to String.

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 Q353. public class a {
   public static void main(String args[]){
      final String s1=""job"";
      final String s2=""seeker"";
      String s3=s1.concat(s2);
      String s4=""jobseeker"";
      System.out.println(s3==s4); // Output 1
      System.out.println(s3.hashCode()==s4.hashCode()); Output 2
   }
}

What will be the Output 1 and Output 2 ?		Core Java
Ans. S3 and S4 are pointing to different memory location and hence Output 1 will be false.

Hash code is generated to be used as hash key in some of the collections in Java and is calculated using string characters and its length. As they both are same string literals, and hence their hashcode is same.Output 2 will be true.

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  Q354. What is the use of HashCode in objects ?Core Java
Ans. Hashcode is used for bucketing in Hash implementations like HashMap, HashTable, HashSet etc.

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 Q355. Will finally be called always if all code has been kept in try block ?Core Java
Ans. The only time finally won't be called is if you call System.exit() or if the JVM crashes first.

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 Q356. Write a Program to add 1-100, 101-200, 201-300 in different threads and then sum the numbers ?Core Java
Ans. public class TotalUsingThreads extends Thread{
   
   private static List<TotalUsingThreads> collector = new ArrayList<TotalUsingThreads>();
   
   private int startFrom = 0;
   
   private Integer threadTotal = null;
   
   Test(int startFrom){
      this.startFrom = startFrom;
   }
   
   
   public static void main(String[] args) throws InterruptedException{
      int totalSum = 0;
      
      // Create all the threads and set the count starting point for all of them
      for(int count=0;count<10;count++){
         TotalUsingThreads newThread = new TotalUsingThreads(count*100);
         newThread.start();
         collector.add(newThread);
      }
      
      boolean allCollected = false;
      
      
      // Make sure that all thread totals are collected and all threads have completed their tasks
      while(!allCollected){
         for(int count=0;count<10;count++){
            if(collector.get(count).threadTotal == null){
               Thread.sleep(100);
               break;
            }
         }
         allCollected = true;
      }
      
      // sum totals of all threads
      for(int count=0;count<10;count++){
         totalSum += collector.get(count).threadTotal;
      }
      
      System.out.println(totalSum);
      
      
   }
   
   public void run(){
      threadTotal = 0;
      for(int count=startFrom;count<startFrom+100;count++){
       threadTotal += count;   
      }
   }
}

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 Q357. If you have access to a function that returns a random integer from one to five, write another function which returns a random integer from one to seven.Core Java
Ans. We can do that by pulling binary representation using 3 bits ( random(2) ).

getRandom7() {
   String binaryStr = String.valuesOf(random(2))+String.valuesOf(random(2))+String.valuesOf(random(2));
   binaryInt = Integer.valueOf(binaryStr);
   int sumValue=0;
   int multiple = 1;
   while(binaryInt > 0){
      binaryDigit = binaryInt%10;
      binaryInt = binaryInt /10;
      sumValue = sumValue + (binaryDigit * multiple);
      multiple = multiple * 2;
   }
}

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 Q358. Write a method to convert binary to a number ?Core Java
Ans.
convert(int binaryInt) {
   int sumValue=0;
   int multiple = 1;
   while(binaryInt > 0){
      binaryDigit = binaryInt%10;
      binaryInt = binaryInt /10;
      sumValue = sumValue + (binaryDigit * multiple);
      multiple = multiple * 2;
   }
   return sumValue;
}

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 Q359. What will be the output of the following code ?

String s1 = "Buggy Bread";
String s2 = "Buggy Bread";
if(s1 == s2)
   System.out.println("equal 1");
String n1 = new String("Buggy Bread");
String n2 = new String("Buggy Bread");
if(n1 == n2)
   System.out.println("equal 2");		Core Java
Ans. equal 1

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 Q360. what will be the output of this code ?

public static void main(String[] args){
   StringBuffer s1=new StringBuffer("Buggy");                       
   test(s1);                    
   System.out.println(s1);              
}       

private static void test(StringBuffer s){      
   s.append("Bread");   
}		Core Java
Ans.  BuggyBread

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