Sample:
public class IfStatement {
public static void main(String[] args) {
java.util.Random random = new java.util.Random();
int number = random.nextInt(2);
System.out.printf("%nTest number: %d%n", number);
// 0 is false
// 1 is true
if (number == 1) {
System.out.print(true);
}
System.out.printf("%n%nThe conditional is complete.%n");
}
}
Sample:
public class IfElse {
public static void main(String[] args) {
java.util.Random random = new java.util.Random();
int number = random.nextInt(2);
System.out.printf("%nTest number: %d%n", number);
// 0 is false
// 1 is true
if (number == 0) {
System.out.print(false);
} else {
System.out.print(true);
}
System.out.printf("%nThe conditional is complete.%n");
}
}
Sample:
public class TernaryOperator {
public static void main(String[] args) {
java.util.Random random = new java.util.Random();
int number = random.nextInt(2);
System.out.printf("%nTest number: %d%n", number);
// 0 is false
// 1 is true
System.out.println(number == 1 ? true : false);
System.out.printf("%n%nThe conditional is complete.%n");
}
}
Sample:
public class IfElseIf {
public static void main(String[] args) {
java.util.Random random = new java.util.Random();
int number = random.nextInt(2);
System.out.printf("%nTest number: %d%n", number);
// 0 is false
// 1 is true
if (number == 0) {
System.out.print(false);
} else if (number == 1) {
System.out.print(true);
}
System.out.printf("%n%nThe conditional is complete.%n");
}
}
Sample:
public class IfLadder {
public static void main(String[] args) {
java.util.Random random = new java.util.Random();
int number = random.nextInt(3);
System.out.printf("%nTest number: %d%n", number);
// 0 is false
// 1 is true
// 2 is neither true nor false
if (number == 0) {
System.out.print(false);
} else if (number == 1) {
System.out.print(true);
} else {
System.out.print("Neither true nor false");
}
System.out.printf("%n%nThe conditional is complete.%n");
}
}
Sample:
public class SwitchStatement {
public static void main(String[] args) {
java.util.Random random = new java.util.Random();
int number = random.nextInt(6);
System.out.printf("%nTest number: %d%n", number);
switch (number) {
case 1:
System.out.print("One");
break;
case 2:
System.out.print("Two");
break;
case 3:
System.out.print("Three");
break;
case 4:
System.out.print("Four");
break;
default:
// if random number is 0 or 5
System.out.print("Number is not between 1 and 4");
break;
}
System.out.printf("%nThe conditional is complete.%n");
}
}Sample (≥ Java 14)
public class EnhancedSwitchStatement {
// requires Java 14 or above
public static void main(String[] args) {
java.util.Random random = new java.util.Random();
int number = random.nextInt(6);
System.out.printf("%nTest number: %d%n", number);
switch (number) {
case 1 -> System.out.print("One");
case 2 -> System.out.print("Two");
case 3 -> System.out.print("Three");
case 4 -> System.out.print("Four");
default -> System.out.print("Number is not between 1 and 4"); // if random number is 0 or 5
}
System.out.printf("%nThe conditional is complete.%n");
}
}
Sample:
public class TryCatch {
public static void main(String[] args) throws java.lang.NumberFormatException {
java.util.Scanner scanner = new java.util.Scanner(System.in);
try {
System.out.println("Enter anything. " +
"Integers pass, " +
"anything else fails." +
"\n\"throw\" throws an exception, and " +
"\"exit\" terminates the program on fail.");
int number = Integer.parseInt(scanner.nextLine());
// Print a "pass" message to the console.
System.out.printf("Pass! number = %d%n", number);
} catch (NumberFormatException nfe) {
// Print a "fail" message to the console.
System.out.printf("Fail! \u001B[31m%s\u001B[0m%n", nfe);
String exitOrThrow = nfe.toString()
.substring(nfe.toString().length() - 6);
if(exitOrThrow
.equalsIgnoreCase("\"exit\"")) { // user entered "exit".
System.exit(1);
} else if(exitOrThrow
.equalsIgnoreCase("throw\"")) { // user entered "throw".
throw new java.lang.NumberFormatException(nfe.toString());
}
} finally {
System.out.println("Thank you for using the Java Try-Catch system. Goodbye!");
scanner.close(); // <- The finally block is a good place to do this.
}
System.out.printf("%n%nThe conditional is complete.%n");
}
}
Sample:
public class WhileLoop {
public static void main(String[] args) {
java.util.Random random = new java.util.Random();
int number = random.nextInt(3);
// 0 breaks and jumps out of loop
// 1 jumps to beginning of loop with continue
// 2 does nothing, program will loop normally
// 3 makes the condition false
while (number < 3) {
System.out.printf("%nStart of loop...%n");
number = random.nextInt(4);
if (number == 0) {
System.out.printf("%nTest number: %d; break%n", number);
break;
} else if (number == 1) {
System.out.printf("%nTest number: %d; continue%n", number);
continue;
} else if (number >= 3) {
System.out.printf("%nTest number: %d; while condition is false%n", number);
} else {
System.out.printf("%nTest number: %d; while condition is true%n", number);
}
System.out.printf("%nEnd of loop...%n");
}
System.out.printf("%n%nThe conditional is complete.%n");
}
}
Sample:
public class DoWhileLoop {
public static void main(String[] args) {
java.util.Random random = new java.util.Random();
// Loop will run once regardless of this value,
// unless a break, continue, or return statement is encountered.
int number = 2112;
// 0 breaks and jumps out of loop
// 1 jumps to beginning of loop with continue
// 2 does nothing, program will loop normally
// 3 makes the condition false
do {
System.out.printf("%nStart of loop...%n");
number = random.nextInt(4);
if (number == 0) {
System.out.printf("%nTest number: %d; break%n", number);
break;
} else if (number == 1) {
System.out.printf("%nTest number: %d; continue%n", number);
continue;
} else if (number >= 3) {
System.out.printf("%nTest number: %d; while condition is false%n", number);
} else {
System.out.printf("%nTest number: %d; while condition is true%n", number);
}
System.out.printf("%nEnd of loop...%n");
} while (number < 3);
System.out.printf("%nThe conditional is complete.%n");
}
}
Sample:
public class ForLoop {
/**
* The for statement begins by declaring a counter variable, (int i = 0;,
* this command is run only the first time in the loop.
* Then a condition is declared that will determine if the loop runs again, i < 4;
* if this condition is true after incrementing, the loop begins again.
* Then a final command is declared that increments the counter after the loop is run, i++)
*/
public static void main(String[] args) {
for (int i = 0; i < 4; i++) {
System.out.printf("%nStart of loop...%n");
System.out.printf("i = %d", i);
System.out.printf("%nEnd of loop...%n");
}
System.out.printf("%nThe conditional is complete.%n");
}
}
Sample:
public class ForEach {
public static void main(String[] args) {
int[] numbers = {1, 2, 3};
for (int number : numbers) {
System.out.println(number);
}
System.out.printf("%nThe conditional is complete.%n");
}
}Sample (List.forEach())
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class ListForEach {
public static void main(String[] args) {
List<Integer> list = new ArrayList<>(Arrays.asList(1, 2, 3));
list.forEach(System.out::println);
System.out.printf("%nThe conditional is complete.%n");
}
}