Methods and variables
Java keyword used to indicate that the value of the variable cannot be changed once it is initially assigned
What is "final"?
List at least 4 different data types
String, boolean, int, double, char
both conditions must be true for the resulting expression to evaluate to true
What is AND?
used to evaluate the relationship between two conditions to either true or false
What are relational operators (eg., ==, !=, >, <, <=, >=)?
Consider the following code segment.
System.out.println(Math.abs(11%4*2)/2);
3
The value of x when
int x = 21/5;
4
What special method is required in order to compile code? (I will give double points if you know it from memory)
The main method
public static void main(String [] args)
if one condition is true, then the resulting expression evaluates to true
What is OR?
what would you use to have mutually exclusive conditional statements?
else if statements
The value of y when
double y = (double)(33/5);
6.0
Any text that is enclosed in double quotes.
What is a string literal?
What is the process called whenever you want to change one data type to another?
casting
What is the difference between = and ==?
= assigns a value to a variable while == compares values of two variables
statements in a program that interrupt the sequential execution of statements
What are conditional or selection statements?
The possible values of a when
int a = (int)(Math.random()) * 4 + 6;
6,7,8,9
what does void mean when written in a method header?
It means you return nothing.
Give an example of the valid way to create an Athlete object in a different class given the following Athlete class definition:
public class Athlete {
private String first_name;
private String last_name;
private int jersey;
public Athlete(String first_name, String last_name, int jersey) {
this.first_name = first_name;
this.last_name = last_name;
this.jersey = jersey;
}
}
Athlete athlete1 = new Athlete("Lebron", "James", 23);
evaluates to the opposite of the expression, denoted with a !
What is NOT?
The value of result after the following command:
String a = "abcdefgh";
String b = "hgfedcba";
String result = a.substring(2) + b.substring(5);
cdefghcba
rearrange("orange") when...
public static String rearrange(String str) {
String temp = "";
for (int i = str.length() - 1; i > 0; i--) {
temp += str.substring(i - 1, i);
}
return temp;
}
What is "gnaro"?
Describe in detail what the return statement does in a method
In Java, every method is declared with a return type such as int, float, double, string, etc.
These return types required a return statement at the end of the method. A return keyword is used for returning the resulted value.
The void return type doesn't require any return statement. If we try to return a value from a void method, the compiler shows an error.
the automatic conversion the Java compiler makes from the wrapper class to the primitive type, Integer to int, Double to double
What is unboxing?
Consider the following code:
String str = "Computer";
How would you correctly extract the last letter of this string?
System.out.println(str.substring(7));
The logic error in the code below:
// Children 3 and under are free
// Ages 4 to under 18: $10 per ticket
// Senior citizen 65 +: $10 per ticket
// All others: $20 per ticket
int price = 0;
if ( age < 18 )
price = 10
else
if ( age >= 65 )
price = 10
else
price = 20
What is...
ages 3 and under will not be free
if ( age >= 4 && age < 18 )
price = 10
abMethod("mississippi", "ss") when
public static String abMethod(String a, String b) {
int x = a.indexOf(b);
while (x >= 0) {
a = a.substring(0, x) + a.substring(x + b.length());
x = a.indexOf(b);
}
return a;
}
What is "miiippi"?