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Questions and Answers
What does the Math class in Java provide?
What does the Math class in Java provide?
A set of static math functions and constants like Math.PI and Math.E.
How do you compute the volume of a sphere using the Math class?
How do you compute the volume of a sphere using the Math class?
Use the formula $\frac{4}{3} \times \pi \times radius^3$ and Math.pow(radius, 3.0) for calculation.
What is the difference between instance methods and class methods in Java?
What is the difference between instance methods and class methods in Java?
Instance methods are sent to objects, while class methods (static) are sent to the class itself.
How is string concatenation achieved in Java?
How is string concatenation achieved in Java?
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What are the two values that the boolean type can hold in Java?
What are the two values that the boolean type can hold in Java?
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Study Notes
Methods
- Java's
Mathclass provides math functions - Part of
Java.lang, no import needed - Static methods, no need to create an object.
- Commonly take double arguments
- Contains constants
Math.EandMath.PI - Useful for calculations like sphere volume using
Math.pow
String Type
- Stores sequences of characters
- Example:
String lastName = "Cat"; - Different String handles can refer to the same String object.
- String literals are 0 or more characters within double quotes.
- Escape sequences usable within literals
- String handle can be
nullor an empty string. - Instance method: a method called on an object of the class (e.g.,
char lastInit = lastName.charAt(0);) - Class method: a method called on the class itself (e.g.,
String PI_STR = String.valueOf(Math.PI);) - Rich set of operations in the Java API
String Methods
-
str.charAt(i): returns the character at indexi -
str.endsWith(str2): isstr2a suffix ofstr? -
str.equals(str2): dostrandstr2contain the same characters (case sensitive)? -
str.equalsIgnoreCase(str2): dostrandstr2contain the same characters (case-insensitive)? - Methods like
indexOf,lastIndexOf,length,toLowerCase,toUpperCase,trim, andsubstringare available for manipulating strings.
The boolean Type
- Holds one of two values:
true(1) orfalse(0) - Used in boolean expressions for program control flow.
- Relational operators (e.g.,
<,>,==,!=) compare operands and return a boolean value - Can be used to build more complex logical expressions
- Example:
boolean seniorStatus = age >= 65; - Relational operators (e.g.,
==,!=,<,>,<=,>=) -
X == Y: Returns true if x and y have same value; otherwise false. -
X != Y: Returns true if x and y have different values; otherwise false. - Logical operators (e.g.,
&&,||,!) used in compound boolean expressions.
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Description
Explore the fundamentals of Java's Math class and String data type in this quiz. Understand how to utilize static methods for calculations and manipulate character sequences effectively. Test your knowledge on key methods and concepts essential for Java programming.
