I need to print the array in this order example: [1, 2, 3, 4], but I don't know how to do it. I started like this:
for (int i = 0; i < a.length - 1; i++) {
return "[" + a[i] + ", "+ "]";
}
return null;
But I only got the first element printed like [1, ]. Can you help me?
Call Arrays.toString(a):
int[] a = {1,2,3,4};
System.out.println(Arrays.toString(a));
Output
[1, 2, 3, 4]
Don't return with single iteration. You have to build the string for all the iterations and then return from there .
StringBuilder builder = new StringBuilder();
builder.append("[");
for (int i = 0; i < a.length - 1; i++) {
builder.append(a[i]).append(",");
}
builder.append("]");
if (builder.length() > 1)
builder.setLength(builder.length() - 1);
return result;
Seems you are learning about arrays and playing with loops.
If you want to use any built in method to do the job use Arrays.toString(a);
if (builder.length() != 0) builder.setLength(builder.length() - 1) before append("]").if statement prevents that.append("]"), otherwise you're removing the ]. ;-)The problem with your code is that you are returning at the first loop iteration.
There are other better and cleaner ways to do it like using:
Arrays.toString(array)
So, you can have:
@Override
String toString() {
return Arrays.toString(a);
}
Build the string in the loop, but don't return until you have processed all the elements:
@Override String toString() {
StringBuilder sb = new StringBuilder();
sb.append("[");
for (int i = 0; i < a.length - 1; ++i) {
sb.append(a[i]);
sb.append(", ");
}
if (a.length > 0) {
sb.append(a[a.length - 1]);
}
sb.append("]");
return sb.toString();
}
I'm assuming that you want to append all elements in the array, you are not intentionally excluding the last one.
Using a StringBuilder is preferable to plain string concatenation, since it is more efficient to accumulate lots of strings that way.
public static void main(String[] args)
{
int[] a = {1,2,3,4};
String res=null;
int num;
res = "[";
for (int i = 0; i < a.length; i++) {
num = a[i];
res = res + num +",";
}
res = res + "]";
System.out.println (res);
}
We build the string during the loop appending to the previous string the next number until the end. Then we print the full string! :)
