Number 10.java

public class Errors
{
    public static void Main(String[] args) // Main to lowercase (main)
    {
        String s = "Hello World!";
        int i = 0;

        {
            if (s.equals(Hello World!)) // Hello World! -> "Hello World!"
                System.out.println(s) // Semicolon at end
        }

        while i < 100 // Surround condition with ()
        {
            if (i % 5 == 0)
                System.out.println(i);
            i++;
        }

        if (calcSum(5, 5) = 10) // single = to ==
            i = 1000;
    }

    private static int calcSum(int a, int b)
    {
        return (a + b);
    }
}

Number 17.java

int[][] matrix = new int[10][10];

for (int i = 0; i < matrix.length; i++) {
    for (int j = 0; j < matrix[i].length; j++) {
        if (i == j) {
            matrix[i][j] = 0;
        } else if (i > j) {
            matrix[i][j] = -1;
        } else {
            matrix[i][j] = 1;
        }
    }
}

Question 6.java

ArrayList<Integer> values = new ArrayList<Integer>(); // The first ArrayList could be just List

values.add(10);
values.add(100);
values.add(342);

for (int i = 642331; i > 0; i -= 21) {
    values.add(i);
}

boolean findWhile(ArrayList<Integer> values, int search) {
    int i = 0;
    while (i < values.size()) {
        if (values.get(i) == search) return true;
        i++;
    }
    return false;
}

boolean findFor(ArrayList<Integer> values, int search) {
    int i = 0;
    for (int i = 0; i < values.size(); i++) {
        if (values.get(i) == search) return true;
    }
    return false;
}

boolean findForEach(ArrayList<Integer> values, int search) {
    for (Integer i : values) {
        if (i == search) return true;
    }
    return false;
}

int largest(ArrayList<Integer> values) {
    int largestIndex = 0;
    for (int i = 1; i < values.size(); ++i) {
        if (values.get(i) > values.get(largestIndex)) {
            largestIndex = i;
        }
    }
    return largestIndex;
}

Question 7.java

int[] fib = new int[35];
fib[0] = 0;
fib[1] = 1;

for (int i = 2; i < fib.length; i++) {
    fib[i] = fib[i - 1] + fib[i - 2];
}

Question 9.java

public class Fraction {
    private int numerator;
    private int denominator;
    
    public Fraction() {
        this(0, 1);
    }
    
    public Fraction(int numerator, int denominator) {
        this.numerator = numerator;
        
        if (denominator == 0) throw new IllegalArgumentException();
        this.denominator = denominator;
    }
    
    public int getNumerator() {
        return numerator;
    }
    
    public void setNumerator(int numerator) {
        this.numerator = numerator;
    }
    
    public int getDenominator() {
        return denominator;
    }
    
    public void setDenominator(int denominator) {
        if (denominator == 0) throw new IllegalArgumentException();
        this.denominator = denominator;
    }
    
    public double getReal() {
        return (double) numerator / denominator;
    }
}