Java Programming

An algorithm is a clear sequence of steps for solving a problem. Before coding, identify inputs, processing, and outputs.

Try it: Write steps to calculate the average of three quiz scores. Identify the inputs, formula, and output.

A Java source file commonly contains a class. Execution in a simple console program begins in the main method.

// HelloGrade12.java
public class HelloGrade12 {
    public static void main(String[] args) {
        System.out.println("Hello, Grade 12!");
    }
}

Save as HelloGrade12.java when the public class is named HelloGrade12. Compile and run using your classroom’s selected Java environment.

A variable names a value that a program can use. Java is statically typed: declarations specify the kind of value.

int age = 17;
double average = 89.5;
char section = 'A';
boolean submitted = true;
String studentName = "Alex";

int total = 80 + 90 + 85;
double mean = total / 3.0;

Common types include int, double, char, boolean, and the reference type String. Operators include arithmetic (+ - * / %), comparison (== != < > <= >=), and logical (&& || !).

Use if/else to choose between paths and loops to repeat work.

int score = 86;
if (score >= 75) {
    System.out.println("Passed");
} else {
    System.out.println("Needs more practice");
}

for (int i = 1; i <= 5; i++) {
    System.out.println(i);
}

Trace the condition carefully. For loops, identify initialization, continuation condition, and update to avoid accidental infinite loops.

A method packages a task into a reusable unit. Parameters receive input; a return value sends a result back.

static double average(double a, double b, double c) {
    return (a + b + c) / 3.0;
}

public static void main(String[] args) {
    double result = average(80, 90, 85);
    System.out.println(result);
}

An array stores a fixed-size sequence of values of one declared element type. Array indexes begin at zero.

int[] scores = {80, 90, 85};
System.out.println(scores[0]); // 80

• Define the intended users and the problem being solved.
• List required inputs, outputs, and validation rules.
• Plan classes or methods before coding.
• Divide tasks fairly and record contributions.
• Test valid, boundary, and invalid cases.
• Prepare a short demonstration and reflection.

int x = 7;
int y = 2;
System.out.println(x / y);
System.out.println(x % y);

Write both outputs before running the program. Explain the difference between division and remainder.

double a = 80;
double b = 90;
double c = 85;
double average = (a + b + c) / 3;
System.out.println(average);

Modify this code so it uses a reusable method and accepts different values. Consider how to handle invalid scores.

Write pseudocode for a program that asks for five numbers and displays the largest. Then draw a flowchart or explain each decision and repetition step.