Java provides "built-in" classes for programmers to use. Some of them are here:
- How to generate a random number between 0.0 - 1.0, 1.0 - 10.0, -10.0 - +10.0?
- How to use absolute values, square root, or power of x?
- Math.random() returns double, how to generate random integers for array indices?
- Is "abc" an object? What's the difference between String x = "abc"; and String x = new String("abc");?
- What will System.out.println("10" + "$") print out? What about System.out.println(10 + "$")?
- How to compare two strings str1 and str2?
Wrapper classes: Integer and Double
- How to create an object from a primitive type value of int or double?
- How to convert an object back to an int or double value?
- How to compare Integer or Double objects?
Object class (To be discussed later):
What are some common behaviors that ALL classes have?
Is Object class a class or an object?
When to override toString() and equals()? What is the hash code of an object?
- How to use substring() and charAt() method of String class to swap any two characters in a string?
- How to find first and last digit of any integer by turning the integer into a string?
- How to convert an integer in decimal system to an integer in binary system or vice versa using Integer.parseInt() and Integer.toBinaryString()?
- Barron's: #1-21 of Chapter 5 "Some Standard Classes"