Java Array Name From String

Question

The code below has a run method which takes in a columnNumber. I have 3 different arrays: col1, col2, and col3 initialized at the top with 4 elements in each of them.

Let's say in the run method, I pass in an int value of 2. So, I would like "s[0] = 500" to be "col2[0] = 500".

So, is there a way to specify which int array that I want by passing in an integer value?

e.g., I type in 3 and then "s[0] = 500" will be "col3[0] = 500"

public class Array {

static int[] col1 = {1, 2, 3, 4};  
static int[] col2 = {1, 2, 3, 4};
static int[] col3 = {1, 2, 3, 4};


public static void run(int columnNumber) {



    String string = Integer.toString(columnNumber);

    String s = "col" + string;

    s[0] = 500;

The run() method should take an int[] array as argument, instead of a column number. And you would thus pass it the array you want the method to modify. — JB Nizet
– JB Nizet, Commented Nov 15, 2014 at 16:51

DanielGibbs · Accepted Answer · 2014-11-15 16:49:28Z

2

You can't (easily) refer to variable names dynamically. What you probably want here is an array of arrays:

static int[][] cols = {
    {1, 2, 3, 4},
    {1, 2, 3, 4},
    {1, 2, 3, 4}
};

public static void run(int columnNumber) {
    cols[columnNumber - 1][0] = 500;
}

I've used columnNumber - 1 because array indices are 0-based. So if you call run(1) it will modify the first array in cols (cols[0]).

answered Nov 15, 2014 at 16:49

DanielGibbs

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Comments

Riyafa Abdul Hameed · Accepted Answer · 2014-11-15 16:59:54Z

0

I suggest that you can use a switch statement.

switch(columnNumber){
      case 1:
          col1[0]=500;
          break;
      case 2:
          col2[0]=500 ;
          break;
      case 3:
          col3[0]=500; 
          break;  
}

answered Nov 15, 2014 at 16:59

Riyafa Abdul Hameed

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devops · Accepted Answer · 2014-11-15 16:52:15Z

0

What about this?

static int[][] columns = { 
                        { 1, 2, 3, 4 },
                        { 1, 2, 3, 4 },
                        { 1, 2, 3, 4 }, 
                        { 1, 2, 3, 4 } 
                        };

public static void run(int columnNumber) {

    columns[columnNumber][0] = 500;

}

answered Nov 15, 2014 at 16:52

devops

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