Reformat a String array

Question

I would like to re-format a String array based on condition. Say, the array

A = ["samsung", "chargers", "fast", "charging", "rapid", "high"]

int index = 1

Which means I will adjoin the items till index 1 with space and format the array. So, finally, it will be,

A = ["samsung chargers", "fast", "charging", "rapid", "high"]

For the index = 2, the output should be,

A = ["samsung chargers fast", "charging", "rapid", "high"]

I write the code that works, I try to find more concise (but not low performance) way.

StringBuilder builder = null;

..........

int fCount = ...

// format the array to match the string
// values = ["samsung", "chargers", "fast", "charging", "rapid", "high"]

builder = new StringBuilder();
String formated = "";

for (int i = 0; i <= fCount; i++) {
    builder.append(values[i]).append(" ");
}

formated = builder.toString().trim();

String[] fVaues = new String[values.length - fCount];

fVaues[0] = formated;

for (int i = 1; i < fVaues.length; i++) {
    fVaues[i] = values[i+1];
}

What is the simple way to accomplish it?

It's literally a simple for loop, we won't provide you with homework when you show no attempt to solve it yourself. — Ivan Kukic
– Ivan Kukic, Commented Feb 28, 2019 at 11:08
As a 1k+ reputation you shouldn't be ask home work question. Hope you aware of this site? — soorapadman
– soorapadman, Commented Feb 28, 2019 at 11:09
@soorapadman I am sorry if I misrepresent myself. I have code that works.... I simply thought there might be a better way to implement it. — Arefe
– Arefe, Commented Feb 28, 2019 at 11:14
if it is to find a better way, maybe you should post this on the review site, instead of on SO — Stultuske
– Stultuske, Commented Feb 28, 2019 at 11:16

ernest_k · Accepted Answer · 2019-02-28 11:31:31Z

4

This method does the same thing:

static String[] joinUntil(String[] original, int until) {
    return Stream.concat(
                Stream.of(String.join(" ", Arrays.copyOf(original, until))),
                Arrays.stream(Arrays.copyOfRange(original, until, original.length))
            ).toArray(String[]::new);
}

answered Feb 28, 2019 at 11:31

ernest_k

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Comments

Ameen · Accepted Answer · 2019-02-28 11:16:12Z

3

private static List<String> reFormat(List<String> lst, int index){
    String joined = String.join(" ", lst.subList(0, index + 1));
    List<String> res = new ArrayList<String>();
    res.add(joined);
    res.addAll(lst.subList(index + 1, lst.size()));
    return res;
}

answered Feb 28, 2019 at 11:16

Ameen

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Comments

Ayrton · Accepted Answer · 2019-02-28 11:20:20Z

2

You could just loop over it, adding the Strings to a second array:

String[] b = new String[a.length - index];
String tmp = a[0];

for(int i = 1; i < a.length; i++) {
    if(i <= index) {
        tmp += " " + a[i];

        if(i == index) {
            b[i - index] = tmp;
        }
    }
    else {
        b[i - index] = a[i];
    }
}

edited Feb 28, 2019 at 11:20

answered Feb 28, 2019 at 11:13

Ayrton

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1 Comment

Arefe Over a year ago

Generally use the StringBuilder like builder = builder.append(values[j]).append(" "); In the decompiled class, the line tmp += " " + a[i]; will be new StringBuilder(" ").append(a[i]). This means in each iteration you creates a new obj which doesn't provides good performance. If its a one-liner, we can safely use them StringBuilder

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