Multidimensioanl Arrays

[Devin Walton]

Hey guys, I've been working on this problem for a week and I haven't made any headway on it. The general idea behind it it that you have to print off a table with 10 columns and three rows. In one column you have names, the other you have to print off their over risk for high cholesterol, and in the third you have to print off their risk of high ldl cholesterol. The third column will call a method, but that's a whole other issue. The problem I'm running into is that I can't get the second column to print. I'm looking for some pointers here and maybe a push in the right direction, I'm not looking for a direct solution. So, here's my code and I would appreciate some feedback on it, thanks

public class pa3
{
	
	public static void main( String [] args)
		{			
			//enter in the dimensions for the table
			final int ROWS = 10;
			final int COLUMNS = 3;
			
			//declare the strings that make up the first column
			String[] names = {"Kristina","Jerome","Eric","Marian","Katherine",
										"Calvin","Melanie","Alison","Donald","William"};
			
			//declare the values the will make up the other two columns
			int [][] totalCholesterol = {289, 224, 293, 267, 153, 233, 236, 199,210, 177};
			int [][] hdlCholesterol =	{62,   46,  23,  41,  81,  52,  67,  31,  71,  55};
			int [][] triglycerides =	{221,  99,  50, 205,  76, 349, 110, 407,  75, 272};
			
			
			//print out the column headings
			System.out.printf("%10s", "Name" + "\t" + "\t" + "Total Cholesterol Risk"
			   + "\t" + "\t" + "LDL Cholesterol Risk Category" + "\n");
			
			//use a for loop to get the first column to print
			for ( int n = 0; n <10; n++)
				{
					System.out.printf("%-3s", names[n] + "\n");
				}
			
			//declare the values for the second second column
			int totalcholesterol = totalCholesterol;  	
			
			if (totalcholesterol >= 240)
				{
					System.out.printf(("%-3s" + "High" + "\n");
				}
			else if(total cholesterol >= 239 && <= 200)
				{
					System.out.printf(("%-3s" + "Borderline High" + "\n");
				}
			else 
				{
					System.out.printf(("%-3s" + "Desireable" + "\n");
				}
		
		}
} 	

[Edit by Winston: Broke up that very long line 21]

[Campbell Ritchie]

Will that program compile?
You are declaring int[][] arrays, which are not multidimensional. Java only supports 1‑dimensional arrays. What you are declaring is arrays of arrays. Anyway, you might declare arrays of arrays, but you are assigning those references to ordinary arrays.
You should not have a ROWS or COLUMNS field. You should get the length of an array out of the array, via its .length field. That way you can have an 11‑element array and still get all its elements.
You have misunderstood the format of the printf arguments. You should have one String with all the % tags in, followed by a comma‑separated list of arguments. You should not need tab characters, because you can use the numbers after % instead. Never use the linefeed character \n. Use the %n tag instead.

[Jelle Klap]

I'm confused about what the table should look like, as I feel you're mixing up columns and rows somewhere in your explanation.
Is this what you're looking for:

       col1   | col2  | col3  | col4 | col5 | col6 | col7 | col8 | col9 | col10
row1 | name1  | name2 | etc.  |      |      |      |      |      |      |
-------------------------------------------------------------------------------
row2 | chol.  |       |       |      |      |      |      |      |      |
-------------------------------------------------------------------------------
row3 | ldl    |       |       |      |      |      |      |      |      |

Or this:

        col1  | col2  | col3 
row1  | name1 | chol. | ldl
-------------------------------
row2  |       |       | 
-------------------------------
row3  |       |       |   
-------------------------------
row4  |       |       | 
-------------------------------
row5  |       |       |   
-------------------------------
row6  |       |       |    
-------------------------------
row7  |       |       |      
-------------------------------
row8  |       |       |     
-------------------------------
row9  |       |       |   
-------------------------------
row10 |       |       |     

In any case, you should think of a "multi-dimensional array" as an array whose elements are other arrays. So when you declare an array like

int[][] intArrayOfIntArrays = new int[3][10];

What this means is: give me an array that stores arrays of int values, and make it one that can store 3 arrays which in turn can store 10 int values.

What you're doing in you code is something different, and illegal:

int [][] totalCholesterol = {289, 224, 293, 267, 153, 233, 236, 199,210, 177};

This means, give me an array that stores arrays of int values and make it one that doesn't store arrays of int values, but these specific int values instead. That doesn't make any sense to the compiler.

What would make this legal is to change the syntax to the following:

int [][] totalCholesterol = {{289}, {224}, {293}, {267}, {153}, {233},
    {236}, {199}, {210}, {177}};

Simply surround the int values with curly brackets, and the compiler will know to treat them as an array initializer, meaning you'll en up with an array of arrays that each hold exeactly one int value.

At any rate, while it's certainly possible to represent a table as an array of arrays, it wouldn't be my first choice in this case, as you need to store different data types (int's and String's). Is the use of a "multi-dimensional array" a requirement of the assignment?

[Winston Gutkowski]

Devin Walton wrote:The general idea behind it it that you have to print off a table with 10 columns and three rows. In one column you have names, the other you have to print off their over risk for high cholesterol, and in the third you have to print off their risk of high ldl cholesterol...

Well, all these arrays seem to refer to a specific thing - a Patient - so why not write a Patient class?

Then you could gather all that separate information into a single array, viz:

Patient[] patients = new Patient[ROWS];
for (int i = 0; i < ROWS; i++) {
   patients[i] = new Patient(names[i], totalCholesterol[i],
      hdlCholesterol[i], triglycerides[i]);
}

or alternatively, simply set it up from scratch:

Patient[] patients = new Patient[] {
   new Patient("Kristina", 289, 62, 221),
   new Patient("Jerome", 224, 46, 99),
   ...
   new Patient("William", 177, 55, 272)
   };

Now you only have one array to worry about, and it contains objects that define exactly what you want - and that's how Object-Orientation works.
(well, part of it )

HIH

Winston

[Red Smith]

You seem to be doing 4 separate arrays and your code only needs to be changed a little:

public class my_pa3  
{  
      
   public static void main( String [] args)  
   {                    
	  //declare the strings that make up the first column  
	  String[] names = {"Kristina","Jerome","Eric","Marian","Katherine",  
						"Calvin","Melanie","Alison","Donald","William"};  
              
	  //declare the values the will make up the other two columns  
	  int[] totalCholesterol = {289, 224, 293, 267, 153, 233, 236, 199,210, 177};  
	  int[] hdlCholesterol =   {62,   46,  23,  41,  81,  52,  67,  31,  71,  55};  
	  int[] triglycerides =    {221,  99,  50, 205,  76, 349, 110, 407,  75, 272};  
              
              
	  //print out the column headings  
	  System.out.printf(
           "Name        Total Cholesterol Risk   LDL Cholesterol   Risk Category \n");  
              
	  //use a for loop to get the first column to print  
	  for ( int n = 0; n < names.length; n++)  
	  {  
		 System.out.printf("%-12s",names[n]);  
              
		 //declare the values for the second second column  
		 int totalcholesterol = totalCholesterol[n];      
              
		 if (totalcholesterol >= 240)  
		 {  
			System.out.printf("%3d High            \n",totalcholesterol);  
		 }						    
		 else if (totalcholesterol <= 239 && totalcholesterol >= 200)  
		 {  
			System.out.printf("%3d Borderline High \n",totalcholesterol);  
         }  
		 else   
		 {  
			System.out.printf("%3d Desireable      \n",totalcholesterol);  
		 }            
	  }  
   }
}

[Red Smith]

This puts the readings into a mutli-dimensional array:

public class pa3_multi {     
   public static void main( String [] args)  
   {                    
	  //declare the strings that make up the first column  
	  String[] names = {"Kristina","Jerome","Eric","Marian","Katherine",  
						"Calvin","Melanie","Alison","Donald","William"};  
              
	  //declare the values the will make up the other two columns  
	  int[][] readings = {
		 {289, 224, 293, 267, 153, 233, 236, 199,210, 177  }, // total cholesterol
		 {62,   46,  23,  41,  81,  52,  67,  31,  71,  55 }, // HDL cholesterol
		 {221,  99,  50, 205,  76, 349, 110, 407,  75, 272 }  // triglycerides
	  };
              
	  //print out the column headings  
	  System.out.printf(
           "Name        Total Cholesterol Risk   LDL Cholesterol   Risk Category \n");  
              
	  //use a for loop to get the first column to print  
	  for ( int n = 0; n < names.length; n++)  
	  {  
		 System.out.printf("%-12s",names[n]);  
              
		 //declare the values for the second second column  
		 int totalcholesterol = readings[0][n];
              
		 if (totalcholesterol >= 240)  
		 {  
			System.out.printf("%3d High            \n",totalcholesterol);  
		 }						    
		 else if (totalcholesterol <= 239 && totalcholesterol >= 200)  
		 {  
			System.out.printf("%3d Borderline High \n",totalcholesterol);  
         }  
		 else   
		 {  
			System.out.printf("%3d Desireable      \n",totalcholesterol);  
		 }            
	  }  
   }
}

[Red Smith]

This puts all the data into a multi-dimensional array:

public class pa3_all_multi{  
     
   public static void main( String [] args)  
   {                    
	  Object[][] patients = {
         {"Kristina","Jerome","Eric","Marian","Katherine",  
		  "Calvin","Melanie","Alison","Donald","William"},   // names 		 
		 {289, 224, 293, 267, 153, 233, 236, 199,210, 177  }, // total cholesterol
		 {62,   46,  23,  41,  81,  52,  67,  31,  71,  55 }, // HDL cholesterol
		 {221,  99,  50, 205,  76, 349, 110, 407,  75, 272 }  // triglycerides
	  };
              
	  //print out the column headings  
	  System.out.printf(
           "Name        Total Cholesterol Risk   LDL Cholesterol   Risk Category \n");  
              
	  //use a for loop to get the first column to print  
	  for ( int n = 0; n < patients[0].length; n++)  
	  {  
		 System.out.printf("%-12s",(String) patients[0][n]);  
              
		 //declare the values for the second second column  
		 int totalcholesterol = (int) patients[1][n];
              
		 if (totalcholesterol >= 240)  
		 {  
			System.out.printf("%3d High            \n",totalcholesterol);  
		 }						    
		 else if (totalcholesterol <= 239 && totalcholesterol >= 200)  
		 {  
			System.out.printf("%3d Borderline High \n",totalcholesterol);  
         }  
		 else   
		 {  
			System.out.printf("%3d Desireable      \n",totalcholesterol);  
		 }            
	  }  
   }
}