Difficulty: Easy<\/strong><\/p>\n\n\n\nThis question appears in nearly every Java Interview Questions for Freshers guide. Interviewers often circle back to this point in Java Interview Questions for Freshers follow-ups.<\/p>\n\n\n\n
Polymorphism allows a single method name to behave differently depending on the object or arguments, achieved through overloading (compile time) or overriding (runtime).<\/p>\n\n\n\n
void log(int x){}\nvoid log(String s){}<\/code><\/pre>\n\n\n\n10. What are access modifiers?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis comes up often across Java Interview Questions for Freshers interviews. Many candidates lose marks here, so revise this before any Java Interview Questions for Freshers round.<\/p>\n\n\n\n
Access modifiers control visibility of a class, method, or variable: public<\/code>, private<\/code>, protected<\/code>, and default (package-private).<\/p>\n\n\n\npublic class Demo {\n private int secret;\n protected int shared;\n}<\/code><\/pre>\n\n\n\n11. What are static variables and methods?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nRecruiters commonly include this in Java Interview Questions for Freshers checklists. Interviewers often circle back to this point in Java Interview Questions for Freshers follow-ups.<\/p>\n\n\n\n
Static members belong to the class rather than any instance, so they can be accessed without creating an object.<\/p>\n\n\n\n
class Counter {\n static int count = 0;\n static void increment(){ count++; }\n}<\/code><\/pre>\n\n\n\n12. What are final variables and methods?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis is a staple entry in most Java Interview Questions for Freshers lists.<\/p>\n\n\n\n
A final<\/code> variable becomes a constant, a final<\/code> method cannot be overridden, and a final<\/code> class cannot be extended.<\/p>\n\n\n\nfinal int MAX = 100;<\/code><\/pre>\n\n\n\n13. What is a constructor?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis question appears in nearly every Java Interview Questions for Freshers guide.<\/p>\n\n\n\n
A constructor initializes objects, shares its name with the class, and has no return type.<\/p>\n\n\n\n
class Point {\n int x, y;\n Point(){ this(0,0); }\n Point(int x, int y){ this.x = x; this.y = y; }\n}<\/code><\/pre>\n\n\n\n14. What is an array?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis comes up often across Java Interview Questions for Freshers interviews.<\/p>\n\n\n\n
An array is a fixed-size collection of elements of the same data type stored in contiguous memory.<\/p>\n\n\n\n
int[] nums = {1, 2, 3};<\/code><\/pre>\n\n\n\n15. What are control structures in Java?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nRecruiters commonly include this in Java Interview Questions for Freshers checklists.<\/p>\n\n\n\n
Control structures direct the flow of execution: if-else<\/code>, switch<\/code>, loops (for<\/code>, while<\/code>, do-while<\/code>), and break<\/code>\/continue<\/code>.<\/p>\n\n\n\nfor(int i = 0; i < 3; i++) System.out.println(i);<\/code><\/pre>\n\n\n\n16. What is exception handling?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis is a staple entry in most Java Interview Questions for Freshers lists.<\/p>\n\n\n\n
Exception handling catches and manages runtime errors gracefully using try<\/code>, catch<\/code>, finally<\/code>, and throw<\/code>, keeping the program from crashing.<\/p>\n\n\n\ntry {\n int x = 10 \/ 0;\n} catch (ArithmeticException e) {\n System.out.println(\"Cannot divide by zero\");\n}<\/code><\/pre>\n\n\n\n17. What is the difference between a private and a protected method in Java?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis comes up often across Java Interview Questions for Freshers interviews.<\/p>\n\n\n\n
A private method is accessible only within the same class, while a protected method is accessible within the same class, package, and subclasses.<\/p>\n\n\n\n
class Base {\n private void secret(){}\n protected void shared(){}\n}<\/code><\/pre>\n\n\n\n18. What is the difference between a while loop and a do-while loop in Java?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis is a staple entry in most Java Interview Questions for Freshers lists.<\/p>\n\n\n\n
A while<\/code> loop checks the condition before executing, while a do-while<\/code> loop executes the body at least once before checking.<\/p>\n\n\n\nint i = 0;\ndo { System.out.println(i); i++; } while(i < 3);<\/code><\/pre>\n\n\n\n19. What is the difference between a static and non-static variable in Java?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis comes up often across Java Interview Questions for Freshers interviews.<\/p>\n\n\n\n
A static variable belongs to the class and is shared by all instances, while a non-static variable belongs to each individual object.<\/p>\n\n\n\n
class Demo {\n static int shared = 0;\n int instanceVal;\n}<\/code><\/pre>\n\n\n\n20. What are text blocks in Java?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis is a staple entry in most Java Interview Questions for Freshers lists.<\/p>\n\n\n\n
Text blocks (Java 15) let you write multi-line strings using triple double-quotes, without escaping every newline or quote.<\/p>\n\n\n\n
String json = \"\"\"\n {\n \"name\": \"Java\"\n }\n \"\"\";<\/code><\/pre>\n\n\n\n21. What is the difference between == and .equals() in Java?<\/h3>\n\n\n\n
Difficulty: Easy<\/strong><\/p>\n\n\n\nThis is a frequently asked question in Java Interview Questions for Freshers rounds.<\/p>\n\n\n\n
==<\/code> compares references (memory addresses) for objects, while .equals()<\/code> compares logical content when overridden, as String<\/code> does.<\/p>\n\n\n\nString a = new String(\"hi\");\nString b = new String(\"hi\");\nSystem.out.println(a == b); \/\/ false\nSystem.out.println(a.equals(b)); \/\/ true<\/code><\/pre>\n\n\n\n22. What are default and static methods in interfaces?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis comes up often across Java Interview Questions for Freshers interviews. Interviewers often circle back to this point in Java Interview Questions for Freshers follow-ups.<\/p>\n\n\n\n
From Java 8 onwards, interfaces can contain default methods (with a body, overridable by implementers) and static methods (called directly on the interface).<\/p>\n\n\n\n
interface Vehicle {\n default void start() { System.out.println(\"Starting\"); }\n static Vehicle create() { return new Car(); }\n}<\/code><\/pre>\n\n\n\n23. What is the Optional class and why is it used?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis is a frequently asked question in Java Interview Questions for Freshers rounds. Keep this answer crisp \u2014 it’s a favorite in Java Interview Questions for Freshers screening rounds.<\/p>\n\n\n\n
Optional<T><\/code>, introduced in Java 8, is a container that may or may not hold a non-null value. It avoids NullPointerException<\/code> by forcing explicit handling of absent values.<\/p>\n\n\n\nOptional<String> name = Optional.ofNullable(getName());\nString result = name.orElse(\"Guest\");<\/code><\/pre>\n\n\n\n24. What are lambda expressions?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis is a frequently asked question in Java Interview Questions for Freshers rounds.<\/p>\n\n\n\n
A lambda expression is a concise anonymous function, written as (parameters) -> expression<\/code>, heavily used with functional interfaces and streams.<\/p>\n\n\n\nList<String> names = Arrays.asList(\"A\", \"B\", \"C\");\nnames.forEach(n -> System.out.println(n));<\/code><\/pre>\n\n\n\n25. What are the different types of exceptions in Java?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis question appears in nearly every Java Interview Questions for Freshers guide.<\/p>\n\n\n\n
Checked exceptions (like IOException<\/code>) are verified at compile time, while unchecked exceptions (like NullPointerException<\/code>) surface only at runtime.<\/p>\n\n\n\nthrow new IllegalArgumentException(\"Invalid input\");<\/code><\/pre>\n\n\n\n26. What is the difference between a HashSet and a TreeSet?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis is a frequently asked question in Java Interview Questions for Freshers rounds.<\/p>\n\n\n\n
A HashSet<\/code> stores unique elements in no particular order using hashing, while a TreeSet<\/code> keeps unique elements sorted using a red-black tree.<\/p>\n\n\n\nSet<Integer> hs = new HashSet<>(List.of(3,1,2));\nSet<Integer> ts = new TreeSet<>(List.of(3,1,2)); \/\/ sorted: 1,2,3<\/code><\/pre>\n\n\n\n27. What is the role of the ClassLoader in Java?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis comes up often across Java Interview Questions for Freshers interviews.<\/p>\n\n\n\n
A ClassLoader loads Java classes into memory at runtime. The three built-in types are Bootstrap, Extension, and Application ClassLoaders, and developers can also write custom loaders.<\/p>\n\n\n\n
ClassLoader cl = Demo.class.getClassLoader();\nSystem.out.println(cl);<\/code><\/pre>\n\n\n\n28. What is the difference between shallow copy and deep copy?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nRecruiters commonly include this in Java Interview Questions for Freshers checklists.<\/p>\n\n\n\n
A shallow copy duplicates fields but shares references, so changes in nested objects affect both copies. A deep copy duplicates the object and everything it references.<\/p>\n\n\n\n
int[] original = {1,2,3};\nint[] deepCopy = original.clone();<\/code><\/pre>\n\n\n\n29. What is the difference between String, StringBuilder, and StringBuffer in Java?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis question appears in nearly every Java Interview Questions for Freshers guide.<\/p>\n\n\n\n
String<\/code> is immutable. StringBuilder<\/code> is mutable and fast but not thread-safe. StringBuffer<\/code> is mutable and thread-safe due to synchronized methods.<\/p>\n\n\n\nStringBuilder sb = new StringBuilder();\nsb.append(\"Java\").append(\" Rocks\");<\/code><\/pre>\n\n\n\n30. What is the difference between an abstract class and an interface in Java?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis comes up often across Java Interview Questions for Freshers interviews.<\/p>\n\n\n\n
An abstract class can hold state and partial implementation but cannot be instantiated. An interface defines a contract of methods (with optional default\/static bodies) that any class can implement.<\/p>\n\n\n\n
abstract class Shape { abstract double area(); }\ninterface Drawable { void draw(); }<\/code><\/pre>\n\n\n\n31. How does garbage collection work in Java?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nRecruiters commonly include this in Java Interview Questions for Freshers checklists.<\/p>\n\n\n\n
Objects are allocated on the heap. When no live references point to an object, it becomes eligible for garbage collection, and the JVM reclaims that memory automatically.<\/p>\n\n\n\n
System.gc(); \/\/ requests GC; JVM decides actual timing<\/code><\/pre>\n\n\n\n32. Provide an example of polymorphism.<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis question appears in nearly every Java Interview Questions for Freshers guide.<\/p>\n\n\n\n
A superclass Animal<\/code> with method makeSound()<\/code> can be overridden differently by subclasses Dog<\/code> and Cat<\/code>, while log()<\/code> shows overloading.<\/p>\n\n\n\nvoid log(int x){}\nvoid log(String s){}\n@Override\npublic String toString(){ return \"Override example\"; }<\/code><\/pre>\n\n\n\n33. What is a daemon thread?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis is a frequently asked question in Java Interview Questions for Freshers rounds.<\/p>\n\n\n\n
A daemon thread is a low-priority background thread (like the garbage collector) that does not stop the JVM from exiting when all user threads finish.<\/p>\n\n\n\n
Thread t = new Thread(() -> System.out.println(\"bg\"));\nt.setDaemon(true);\nt.start();<\/code><\/pre>\n\n\n\n34. How do you implement a bubble sort algorithm in Java?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nRecruiters commonly include this in Java Interview Questions for Freshers checklists.<\/p>\n\n\n\n
Bubble sort repeatedly swaps adjacent elements that are out of order.<\/p>\n\n\n\n
void bubble(int[] a){\n for(int i=0;i<a.length-1;i++)\n for(int j=0;j<a.length-i-1;j++)\n if(a[j]>a[j+1]){ int t=a[j]; a[j]=a[j+1]; a[j+1]=t; }\n}<\/code><\/pre>\n\n\n\n35. How do you implement a binary search algorithm in Java?<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis question appears in nearly every Java Interview Questions for Freshers guide.<\/p>\n\n\n\n
Binary search repeatedly halves a sorted array to locate the target element.<\/p>\n\n\n\n
int binSearch(int[] a, int key){\n int l=0, r=a.length-1;\n while(l<=r){\n int m=(l+r)\/2;\n if(a[m]==key) return m;\n if(a[m]<key) l=m+1; else r=m-1;\n }\n return -1;\n}<\/code><\/pre>\n\n\n\n36. What is a thread in Java? Provide an example of how to create a thread.<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis is a frequently asked question in Java Interview Questions for Freshers rounds.<\/p>\n\n\n\n
A thread<\/a> is a lightweight process that runs independently. Threads are created by extending Thread<\/code> or implementing Runnable<\/code>.<\/p>\n\n\n\nclass MyJob implements Runnable {\n public void run(){ System.out.println(\"Work\"); }\n}\nnew Thread(new MyJob()).start();<\/code><\/pre>\n\n\n\n37. Explain marker interfaces vs functional interfaces.<\/h3>\n\n\n\n
Difficulty: Medium<\/strong><\/p>\n\n\n\nThis is a staple entry in most Java Interview Questions for Freshers lists.<\/p>\n\n\n\n
A marker interface has no methods and simply tags a class for special behavior (Serializable<\/code>, Cloneable<\/code>). A functional interface has exactly one abstract method and powers lambda expressions (
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