I use JBuilder. It's old but is what we used at uni. Version 5 maybe. Maybe you could get that from some p2p fileshare or whatever.


16. (a) Implement the method

public static char toLower(char c)
{
	// Characters are just numbers - Look at the DEC column in http://www.lookuptables.com/asciifull.gif
	// You'll notice that the difference between 'a' and 'A', or 'b' and 'B' is always the same.
	
	// So first let's test if the char is an Uppercase character
	bool charIsUppercase = ( (c>='A') & (c<='Z') );	

	// If it is not uppercase, then there's no need to convert. (It could even be a symbol like '?')
	if( !charIsUppercase )
		return c;

	// If we get here, it is uppercase. 
	// So let's find out the 'difference' between a uppercase and a lowercase character
	int fromUpperToLower = 'a' - 'A';

	// So add that value to our char to convert it to lower
	char convertedToLower = c + fromUpperToLower;

	// And return it
	return convertertedToLower;		
}


16. (b) Implement the method

public static boolean isIdChar(char c)
{
	// I think a Java identifier can only begin with 'a' to 'z' or 'A' to 'Z'

	if( (c>='A') & (c<='Z') ) 	// If it's an uppercase char, then it is valid
		return true;

	if( (c>='a') & (c<='z') ) 	// If it's a lowercase char, then it is also valid
		return true;

	return false;			// If we get here, then it must be a symbol, and is therefore invalid
}


17. Consider the method:

public static void f(int[] arr, int item)
{
	for(int i=0; i< arr.length; i++)
		if(arr[i]<0)
			arr[i] = item;
}

Assume the declaration:
int[] intList = {-1, 5, 3, -77, -9};

(a) The contents of intList should remain the same.
(b) The contents of intList should remain the same.

This is because arrays are passed by 'value'. The function f() receives a 'copy' of the array intList. So when it makes a change to the arr[i], it will change arr[i] (the copy) but not the intList[i] (the original). BTW check it out for yourself just to be sure.



18. What is the output of the program?

public class NumberSystems
{
	public static void main(String[] args)
	{
		int[] binary = {1,0,1,1};
		int[] octal  = {5,4,0,1};

		baseNumber(2,binary);
		baseNumber(8,octal);
	}

	public static void baseNumber(int b, int[] d)
	{
		int a[] = {1,b, b*b, b*b*b};		// Create a series in the base b e.g. 1,2,4,8

		for(i = d.length-1; i >=0; i--)		// Reverse through the array
			sum += d[i]*a[i];		// Multiply the input by the series 

		System.out.println("The number " + d[3] + d[2] + d[1] + d[0] + " (base " + b + ") = " + sum);		
	}
}

Output of the program:
The number 1011 (base 2) = 11
The number 5401 (base 8) = 2817



PROGRAMMING EXERCISES
1. (a) Implement a method that takes a double parameter x and outputs whether x lies in the range between 0.0 <= x <= 1.0

void outputInRange(double x)
{
	if( x>=0.0 & x<= 1.0 )
		System.out.println("x lies in the range between 0.0 <= x <= 1.0");
	else
		System.out.println("x does NOT lie in the range between 0.0 <= x <= 1.0");
}


1. (b) Write a main program that declares the array

public static void main(String[] args)
{
	double[] arr = {.897, 1.67, 9.89, -.279, .53, 1.0, 1.01, 0.0};

	for(int i=0; i<arr.length; i++)
		outputInRange(arr[i]);
}


2. For an integer n, the remainder operation n%10 returns the rightmost or units digit of the number.

void outputReverse(int number)
{
	// For example, during 365
	int remainder = 0;		// remainder = 5
	int valueLeft = number;		// valueLeft = 36

	for(;;)
	{
		remainder = valueLeft % 10;	// e.g. 365%10 = 5;
		valueLeft = valueLeft / 10;	// e.g. 365/10 = 36
		System.out.print( remainder );			

		if( valueLeft == 0 )		// If there is nothing left to divide
			break;			// Break out of the loop
	}

	System.out.println();			// Print a line... optional
}

2 (b)

public static void main(String[] args)
{
	int[] arr = {365, 5689, 78, 0, 135737};

	for(int i=0; i<arr.length; i++)
	{
		outputReverse( arr [i] );
	}
}



3 (a)
public static void cumulate(int[] arr, int[] cum)
{
	int total = 0;
	for(int n=0; n<arr.length; n++)
	{
		total = 0;			// Reset the total
		for(int c=0; c<n; c++)		// Start adding
		{
			total+= arr[c];
		}	
		cum[n] = total;			// Save the total
	}
}

(b)
public static void main(String[] args)
{
	int[] arr = {1, 2, 7, 12, 16};
	int[] cum = new int[5];
	
	cumulate(arr, cum);
	for(int i=0; i<arr.length; i++)
	{
		System.out.println(cum[i]);	// Print out each cumulative number on a line
	}
}