Conditionals/Basics
What type of variable/result can contain the values true or false?
Booleans
What is a method?
A block of code that, when called, will preform all code inside of it
What is a char/Character?
A single character or symbol, separate of type string and surrounded by single quotations
What is a while loop?
This loop is indefinite, and will continue to repeat unless a condition is met
Create a new array with a length of 5
int arr [] = new int [5];
This code is used to check if a statement or expression is true or false
What is an if statement?
Label the parts of this method
public static int Review (int x, int y){
}
Access modifiers: public static
Return type: int
Method name: Review
Parameter(s): x, y
This method extracts and returns a part of a string from a start and end value.
What is a substring?
This loop is definite, and requires a starting value, an end value, and how many times the value should increase
What is a for loop?
What is an array?
A collection of data of a similar type; its individual values can vary
Create a block of code that checks if two integers input are either 6, or if their sum is a multiple of 6
Use this method to start your code:
public static boolean six (int a, int b){
}
if (a==6 || b==6){
return true;
}else if ( (a+b) % 6 == 0 ){
return true;
}
return false;
}
Create a method that will return the minimum of three numbers
public static int minimunNum (int a, int b, int c){
return Math.min(Math.min(a, b), c);
}
What does this code print
String str = "Coding";
System.out.print(str.charAt(5));
'n'
Create code that will print a line of symbols, entered by the user, an n amount of times, also entered by the user
System.out.println("Number of Symbols: ");
Integer x = Integer.parseInt(scan.nextLine());
System.out.println("Enter Symbol");
String y = scan.nextLine();
for (int i = 0; i <x; i++ ){
System.out.print(y + " ");
}
How do you iterate through an array?
Using a for loop
Create code that will convert the integer 5364, in seconds, into hours and minutes and seconds.
1 hr, 29 mins, 24 second
int h = left/3600;
left = left%3600;
int m = left/60;
left = left % 60;
int seconds = left/1;
left = left % 1;
System.out.println("Hours: " + h);
System.out.println("Minutes: " + m);
System.out.println("Seconds: " + seconds);
Create this pattern:
1
12
123
1234
12345
1234
123
12
1
public static void pattern(int x){
for (int i = 1; i <x; i++){
System.out.println(" ");
for (int n = 1; n <= i; n++){
System.out.print(n);
}
}
for (int i = x; i > 0; i--){
System.out.println(" ");
for (int n = 1; n <= i; n++){
System.out.print(n);
}
}
}
What does this code do?
BONUS: What is the value of count when str is "racecar"?
public static int unknown2 (String str){
int count = 0;
for (int i = 0; i < str.length(); i++){
if (str.charAt(i) == 'c'){
count++;
}
}
return count;
}
Returns how many times the character "c" appears in a string
Trace this code (BONUS: What does this code do?) :
for (int x = 1; x <= 15; x++) {
if (x%3 ==0){
System.out.print(x +" "+ x+ " ");
} else if (x%2 != 0){
System.out.print(x+" ");
}
}
1 3 3 5 6 6 7 9 9 11 12 12 13 15 15
Bonus: Prints every odd number from 1-15, with the exception that if the number is a multiple of three then print the number twice
Trace this array when arr is {1, 8, 3, 4, 8, 8, 1}, what does the method return?:
public static int unknown3(int[] arr){
int count = 0;
for (int i =0; i<arr.length-1; ++i){
if (arr[i] == 8 && arr[i+1] == 8){
count = count + 2;
}
if (arr[i] == 8){
count++;
}
}
return count;
}
This method returns 4
Trace this code when "a" is 13
BONUS: What does this code do?
public static boolean unknown (int a){
for (int i = 2; i < a; i++){
if (a%i == 0){
return false;
}
}
return true;
}
Returns true
BONUS: Returns true if the number is a prime number
Create a method that will find the greatest common factor of two numbers
public static int gcf (int x, int y){
int gcFactor = 0;
int max = (Math.max(x, y));
for (int i = 1; i < max ; i++){
if (x % i == 0 && y % i == 0){
gcFactor = i;
}
}
return (gcFactor);
}
Create a block of code that wil mix two strings together flipping between each strings characters
ex: ("Hello", "Bye")
Output: (HBeylelo)
Use this method to start your code:
public static String mixString(String a, String b) {
public static String mixString(String a, String b) {
String ans = "";
if (a.length()>=b.length()){
for (int i = 0; i < b.length(); i++){
ans = ans + a.charAt(i);
ans = ans+b.charAt(i);
}
ans = ans + a.substring(b.length());
}else if (b.length()>=a.length()){
for (int i = 0; i < a.length(); i++){
ans = ans + a.charAt(i);
ans = ans+b.charAt(i);
}
ans= ans + b.substring(a.length());
}
return ans;
}
Create a block of code that will determine if a number is abundant or deficient
(A number is deficient if the sum of its divisors is less than the number (1 AND THE NUMBER EXCLUSIVE))
int factor = 0;
int sum = 0;
System.out.println("ENTER A NUM");
Integer x = Integer.parseInt(scan.nextLine());
for (int i = 1; i < x; i++){
if (x%i == 0){
sum = i+sum;
factor = factor+1;
}
}
if (sum>x){
System.out.println("Abundant");
}else{
System.out.println("Deficient");
}
Create code that will take an array and return the max, min, and average of all elements
Use this method to start your code
public static void checkArray(int[] arr){
public static void checkArray(int[] arr){
double count = 0;
double average = 0;
double min = arr[0];
double max = arr[0];
for (int i = 0; i <arr.length;++i){
average = average + arr[i];
count++;
if (arr[i] < min){
min = arr[i];
}else if (arr[i] > max){
max = arr[i];
}
}
System.out.println(max +" "+ min +" "+ average/count );
}