Guide
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import java.util.ArrayList;
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import java.util.HashMap;
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public class Main {
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public static void main(String[] args) {
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int x = 18;
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// method1(x); System.out.println(x);
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for (int i = 0; i < 10; i++) {
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System.out.println(i + " Hello World!");
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}
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// TODO: While Loop
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// Output: Same As For Loop Shown Previously
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int p = 0;
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while (p < 10) {
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System.out.println(p + " Hello World!");
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p++;
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}
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// TODO: Do While Loop
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/* Note: Condition is checked at the end
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* so the loop will ALWAYS execute
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* at least once, even if the condition
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* is false.
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* Output: Goudham
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*/
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int j = 0;
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do {
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System.out.println("Goudham");
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} while (j != 0);
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// // TODO: If Else Statement
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// // Operator Used: Less Than (<)
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// // Output: You Are Rich!
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// double balance = 500.00;
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// if (balance < 500.00) {
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// System.out.println("You Are Broke");
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// } else {
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// System.out.println("You Are Rich!");
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// }
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// TODO: If else if else if... Statement
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// Operator(s) Used: Logical AND (&&), Logical NOT (!),
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// Greater Than (>), Greater Than Or Equal To (>=),
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// Less Than (<),
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// Output: You Are Rich and not in Debt
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double balance = 100.00;
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boolean debt = false;
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if (balance < 100.00 && debt) {
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System.out.println("You are Broke and in Debt");
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} else if (balance >= 100.00 && debt) {
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System.out.println("You are Rich but in Debt");
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} else if (balance < 100.00 && !debt) {
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System.out.println("You are Broke and not in Debt");
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} else if (balance >= 100.00 && !debt) {
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System.out.println("You are Rich and not in Debt");
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}
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// TODO: Switch Case Statement
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/* Note: There is no major difference between this and
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if else if else if... The switch statement
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improves readability and clarity.
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*/
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// Output: Wednesday
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int day = 3;
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switch (day) {
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case 1:
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System.out.println("Monday");
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break;
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case 2:
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System.out.println("Tuesday");
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break;
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case 3:
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System.out.println("Wednesday");
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break;
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case 4:
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System.out.println("Thursday");
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break;
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case 5:
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System.out.println("Friday");
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break;
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case 6:
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System.out.println("Saturday");
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break;
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case 7:
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System.out.println("Sunday");
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break;
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default:
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System.out.println("Day Not Specified");
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}
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// TODO: Another If Statement
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// Operator Used: Logical NOT (!)
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// Output: You Are Broke
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boolean rich = false;
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if (!rich) {
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System.out.println("You Are Broke");
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}
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// TODO: Common String Methods
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String helloWorld = "Hello World!";
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// TODO .toUpperCase()
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// Converts the entire string into uppercase format
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// Return Type: String
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// Output: HELLO WORLD!
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System.out.println(helloWorld.toUpperCase());
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// TODO: .toLowerCase()
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// Converts the entire string into lowercase format
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// Return Type: String
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// Output: hello world!
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System.out.println(helloWorld.toLowerCase());
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// TODO: .isEmpty()
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// Checks to see if the string is empty or not
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// Return Type: boolean
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// Output: false
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System.out.println(helloWorld.isEmpty());
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// TODO .length()
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// Returns the length of the string given
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// Return Type: int
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// Output: 12
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System.out.println(helloWorld.length());
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// TODO .concat()
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// Appends a string onto the end of another string
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// Return Type: String
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// Output: Hello World!World
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System.out.println(helloWorld.concat("World"));
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// TODO .contains()
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// Checks to see a string is present within another string
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// Return Type: boolean
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// Output: true
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System.out.println(helloWorld.contains("Hello"));
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// TODO .equals()
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// Checks if 2 strings are equal
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// Return Type: boolean
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// Output: true
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System.out.println(helloWorld.equals("Hello World!"));
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// TODO .trim()
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// Erases whitespace from both sides of the string
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// Return Type: String
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// Output: Hello World!
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System.out.println(helloWorld.trim());
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// TODO: Array Declaration
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// Note: Both ways are valid HOWEVER, <type>[] <name> is the preferred/conventional method
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String[] jedi = new String[5];;
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String sith[] = new String[5];;
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// TODO: Array Declaration with Literal Syntax
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String[] lecturers = new String[] {"Matthew", "Derek", "Waqar"};
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String[] lecturers1 = {"Matthew", "Derek", "Waqar"};
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// TODO: Array Common Operations
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// String[] jedi = new String[] {"Goudham", "Luke", "Ahsoka"};
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// TODO: Change Element
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// Note: We need to specify the index of the value that we want to change
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// Result: First Element is now "Matthew"
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jedi[0] = "Matthew";
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// TODO: Find Array Length
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// Result: Returns the number of elements in an array
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int lengthOfJediArray = jedi.length;
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// TODO: Loop Through Array
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for (int i = 0; i < jedi.length; i++) {
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String currentJedi = jedi[i];
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// ...
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}
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// TODO: Displaying Arrays
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System.out.println(jedi);
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// TODO: ArrayList Declaration
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ArrayList<String> names = new ArrayList<>();
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// TODO: HashMap Declaration
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HashMap<String, String> jediKnights = new HashMap<>();
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}
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static void method1(int i) {
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i = 20;
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}
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}
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