在除最后一个数组之外的数组项之间插入分号

Question

Based from the accepted answer from this post , I have this code:

if (authors.length >= 1) {
    System.out.print(authors[0]);
}

for (int i = 1; i < authors.length; i++) {
    System.out.print("; " + authors[i]);
}

So the output of this is author1; author2; author3 author1; author2; author3 author1; author2; author3 How can I change this into author1; author2 & author3 author1; author2 & author3 ? If there are only 2 authors, the output should be author1 & author2 . Thanks in advance.

Answer 1

You'd just need to add in one conditional to your loop to handle the last case:

for (int i = 1; i < authors.length; i++) {
    if(i == authors.length - 1)
        System.out.print("& " + authors[i]);
    else
        System.out.print("; " + authors[i]);
 }

Answer 2

One way to do it would be changing the structure of the code to use a loop and a boolean flag instead of a conditional, like this:

boolean isFirst = true;
for (int i = 0 ; i != authors.length ; i++) {
    if (!isFirst) {
        System.out.print(i == authors.length-1 ? "& " : "; ");
    } else {
         isFirst = false;
    }
    System.out.print(authors[i]);
}

Demo.

Answer 3

You can do it recursively to separate cases clearly. Seems like other answers lack that.

This is the proxy function:

public static String doIt(String[] authors){

    if (authors == null || authors.length == 0){
        return "";
    }

    if (authors.length == 1){
        return authors[0];
    }

    return authors[0] + doHelper(authors, 1);

}

And the helper function:

public static String doItHelper(String[] authors, int index){
    if (index == authors.length - 1){
        return " & " + authors[index];
    }
    return "; " + authors[index] + doItHelper(authors, index + 1);

}

As mentioned in comments (Thanks @JNYRanger) this is not optimal when performance is an issue.

Can't test it now, so I hope the idea is clear.

Answer 4

Try it this way:

    String[] authors = { "1", "2", "3", "4", "5" };

    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < authors.length; i++) {

        sb.append(authors[i]);
        if (i + 2 < authors.length) {
            sb.append(";");
        } else if (i + 2 == authors.length) {
            sb.append("&");
        }
    }
    System.out.print(sb.toString());

Answer 5

for (int i = 0; i < authors.length; i += 1) {
    if (i > 0) {
        System.out.print(i < authors.length - 1 ? "; " : " & ");
    }
    System.out.print(authors[i]);        
}

Answer 6

String[] authors = {"a", "b", "c", "d"};
for (int i = 0; i < authors.length; i++) {
   System.out.print((i != 0 ? (i == authors.length - 1 ? " & " : "; ") : "") + authors[i]);
}