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Questions and Answers
What is the output of the code System.out.println(Math.pow(2, 3));?
What is the output of the code System.out.println(Math.pow(2, 3));?
What is a number literal in Java?
What is a number literal in Java?
What is the data type of the literal 5.0 in Java?
What is the data type of the literal 5.0 in Java?
What does the method System.currentTimeMillis() return?
What does the method System.currentTimeMillis() return?
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What is the main difference between the ++i and i++ operators?
What is the main difference between the ++i and i++ operators?
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What does type casting in Java refer to?
What does type casting in Java refer to?
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What is the data type of a variable that can store a single character?
What is the data type of a variable that can store a single character?
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What is the purpose of the Character.isDigit() method?
What is the purpose of the Character.isDigit() method?
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Study Notes
Java Variables and Data Types
- Variable Declaration: Used to store values in a program.
- Number Literal: A constant numerical value appearing directly in the code. Not a variable.
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Math.pow(2, 3)Output: 8.0 -
5.0Data Type:double -
System.currentTimeMillis()Purpose: Gets the current time in milliseconds since the Unix epoch. -
Increment Operators (
++ivsi++):++iincrements the value before use,i++after.
Java Operators and Expressions
- Type Casting: Converting a variable from one data type to another.
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int i = (int)3.9;Output 3 (integer truncation)
Java Random Numbers and Characters
- Random Integer (1-10): Methods exist for this but are not detailed.
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Character Data Type:
char - Unicode: A 16-bit character encoding scheme.
- Escape Sequence: A sequence of characters representing a special character (e.g., newline).
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Character.isDigit()Purpose: Checks if a character is a digit. -
String Data Type:
String -
String.length()Purpose: Retrieves the length (number of characters) of a string. -
String.charAt()Purpose: Returns the character at a specific index in a string. -
String.concat()Purpose: Concatenates (joins) two strings.
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Description
Test your knowledge on Java variables, data types, and operators. This quiz covers topics like variable declaration, data types, and the use of mathematical functions in Java. Get ready to check your understanding with practical examples and concepts!
