CODEWITHSUNDEEP
javaarraysforeach
Anurag
Anurag

Reputation: 733

For-each Loop in Java

I have a sample code which creates an "array" of size 10 and tries to initialize it with reverse values in a For loop e.g:(9,8,7,6,5...0):

int[] array = new int[10];
        for (int i = array.length - 1, j = 0; i >= 0; i--, j++) {
            System.out.println("Present value of i=" + i
                    + " Present value of j=" + j);
            array[j] = i;
            System.out.println("Array:" + j + "=" + i);
        }
        for (int k : array) {
            System.out.println(array[k]);
        }

So far so good. This is the output from console which is perfect:

Present value of i=9 Present value of j=0
Array:0=9
Present value of i=8 Present value of j=1
Array:1=8
Present value of i=7 Present value of j=2
Array:2=7
Present value of i=6 Present value of j=3
Array:3=6
Present value of i=5 Present value of j=4
Array:4=5
Present value of i=4 Present value of j=5
Array:5=4
Present value of i=3 Present value of j=6
Array:6=3
Present value of i=2 Present value of j=7
Array:7=2
Present value of i=1 Present value of j=8
Array:8=1
Present value of i=0 Present value of j=9
Array:9=0

The issue is with For-each loop in the end which is just printing the values in array:

for (int k : array) {
            System.out.println(array[k]);
        }

The values printed array are 0,1,2...9 where it should be 9,8,7...0

When I use the regular For loop to print the array, it works normally. Am I missing some funny business here?

Upvotes: 3

Views: 791

Answers (3)

Moni
Moni

Reputation: 433

This for loop, for (int k : array) is basically gives you the array value in detail this for loop is like -

int k = array[0] = 9 int k = array[1] = 8 .....

and again you are trying to print array[9] , array[8] which gives you result like 0,1,2... replace for( int k : array){ System.out.println(array[k]); }

with for(int k : array){ System.out.println(k); }

Upvotes: 0

ajb
ajb

Reputation: 31699

Basically, since (int k : array) causes k to go through the values in the array, not the indexes, what you've done is equivalent to

System.out.println(array[array[0]]);
System.out.println(array[array[1]]);
System.out.println(array[array[2]]);
System.out.println(array[array[3]]);
...
System.out.println(array[array[9]]);

which isn't what you want.

Upvotes: 7

rgettman
rgettman

Reputation: 178363

You are already getting the values out of the array with your foreach loop, which you are using as an index again into the array, yielding the values in order again.

Just print k. Change

for (int k : array) {
    System.out.println(array[k]);
}

to

for (int k : array) {
    System.out.println(k);
}

End of the output:

9
8
7
6
5
4
3
2
1
0

Upvotes: 11

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