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Wrapper Classes
Last Updated : 26 May, 2026
title: Wrapper Class in Java
OOPs53 words4 headingsTables includedExamples included
title: Wrapper Class in Java description: Primitive types ke wrapper classes
Har primitive type ka ek corresponding Wrapper class hota hai.
| Primitive | Wrapper |
|---|---|
| byte | Byte |
| short | Short |
| int | Integer |
| long | Long |
| float | Float |
| double | Double |
| char | Character |
| boolean | Boolean |
Autoboxing aur Unboxing
java exampleWoHoTech
// Autoboxing: primitive → Object
int num = 42;
Integer obj = num; // automatic conversion
// Unboxing: Object → primitive
Integer obj2 = 100;
int n = obj2; // automatic conversionInteger Class Methods
java exampleWoHoTech
Integer.parseInt("123") // String to int: 123
Integer.toBinaryString(10) // "1010"
Integer.toHexString(255) // "ff"
Integer.toOctalString(8) // "10"
Integer.MAX_VALUE // 2147483647
Integer.MIN_VALUE // -2147483648
Integer.compare(5, 10) // negative (5 < 10)
Integer.sum(5, 3) // 8String to Primitive
java exampleWoHoTech
int i = Integer.parseInt("42");
double d = Double.parseDouble("3.14");
boolean b = Boolean.parseBoolean("true");
long l = Long.parseLong("123456789");Caching in Integer
java exampleWoHoTech
Integer a = 127;
Integer b = 127;
System.out.println(a == b); // true (cached -128 to 127)
Integer c = 200;
Integer d = 200;
System.out.println(c == d); // false (naya object)
// Always use .equals() for comparisonExam Focus
Revise definitions, diagrams, examples, and short-answer points for Wrapper Classes.
Interview Use
Prepare one clear explanation, one practical example, and one common mistake for this Java topic.
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