String SomeLongString = JavaAPIMethodFor (String[] strings, String delimeter)

Question

String SomeLongString = JavaAPIMethodFor (String[] strings, String delimiter);

Or this could work as well:

String SomeLongString = JavaAPIMethodConvertingArrayWithDelimeter (String[] strings, char delimiter)

I wanted to join strings into a larger string, but this is simply useless. I am aware that I could append all the data into a string using Arrays.toString(Object someString) then adjust the string, removing unwanted characters. But that's not really efficient, building something, only to rebuild it. So looping through the String[] and adding my character[s] between each element is probably the way to go:

import static org.junit.Assert.*;

import org.junit.Test;

public class DelimetedString {


    private String delimitedString(String [] test, String delimiter){
        StringBuilder result = new StringBuilder();
        int counter = 0;
        if(test.length > counter){
           result.append(test[counter++]);
           while(counter < test.length){
              result.append(delimiter);
              result.append(test[counter++]);
           }
        }
        return result.toString();
    }

    @Test
    public void test() {
        String [] test = new String[] 
{"cat","dog","mice","cars","trucks","cups","I don't know", "anything!"};
        String delimiter = " |...| ";
        assertEquals("DelimitedString misformed",
        "cat |...| dog |...| mice |...| cars |...| trucks "
            +"|...| cups |...| I don't know |...| anything!",
        delimitedString(test, delimiter));
    }

}

What I wanted was something to put together a string after using a tokenizer. I abandoned that Idea, since it's probably more cumbersome then it's worth. I chose to address a Sub-Strings from within the larger String, I included the code for that, in an "answer".

What I was asking is - Does the java API have an equivalent function as the delimitedString function? The answer from several people seems to be no.

I'm not sure what the question is. You want a standard JDK API function for one that doesn't exist? I just use Commons' `StringUtils.join` for this. — Dave Newton, Nov 16 '11 at 22:19
I don't believe there is a built in API method for doing what you are looking for, but a `StringBuilder` and a for loop will make quick work of the operation. — John Haager, Nov 16 '11 at 22:19
possible duplicate of [String Operations in Java](http://stackoverflow.com/questions/187676/string-operations-in-java) — unholysampler, Nov 16 '11 at 22:22

Martijn Courteaux · Accepted Answer · 2011-11-16T22:33:18.647

1

As far as I know, there isn't a built in method. What you can do is taking the substring of it:

String str = Arrays.toString(arrayHere);
str = str.substring(1, str.lenght() - 1);

edited Nov 16 '11 at 22:33

answered Nov 16 '11 at 22:26

Martijn Courteaux

67,591
47
198
287

score 1 · Answer 2 · answered Dec 04 '11 at 00:23

Here is a class that I ended up throwing together. I want to break apart a text file into chunks, then send the chunks through a Servlet using the row number to obtain the relevant data. This is a app running on a server in my home that will allow me to read my text files across different devices, and keep meta-data related to a file.

package net.stevenpeterson.bookreaderlib;

public class SplitStringUtility {

private String subject;

public SplitStringUtility(String subject) {
    this.subject = subject;
}

public String getRow(int rowAddress, int charsPerRow) {
    String result = "";
    if (rowAddress >= 0 && charsPerRow > 0) {
        int startOfSubString = rowAddress * charsPerRow;
        int endOfSubString = startOfSubString + charsPerRow;
        result = getSubString(startOfSubString, endOfSubString);
    }
    return result;
}

private String getSubString(int startOfSubString, int endOfSubString) {
    String result = "";
    if (startOfSubString <= subject.length()) {
        if (endOfSubString <= subject.length()) {
            result = subject.substring(startOfSubString, endOfSubString);
        } else {
            result = subject.substring(startOfSubString);
        }
    }
    return result;
}

}

I tested against:

package net.stevenpeterson.bookreaderlib;

import static org.junit.Assert.*;

import net.stevenpeterson.bookreaderlib.SplitStringUtility;

import org.junit.Test;

public class SplitStringUtilityTest {

    public final String empty = "";
    public final String single ="a";
    public final String twoChars = "ab";
    public final String threeChars = "abc";
    public final String manyChars = "abcdefghijklmnopqrstuvwxyz";

    private SplitStringUtility splitter;

    @Test
    public void splitTestsEmpty() {
        makeSplitter(empty);
        assertEquals("We are trying to get a non-existant string",
            "", 
            splitter.getRow(3,4));
    }


    @Test
    public void splitTestsNegativeRowOrColumn() {
        makeSplitter(manyChars);
        assertEquals("We are trying to get a non-existant string",
            "",
            splitter.getRow(-3,4));

        assertEquals("We are trying to get a non-existant string",
            "", 
            splitter.getRow(-1,-1));

        assertEquals("We are trying to get a non-existant string",
            "", 
            splitter.getRow(1,-1));
    }



    @Test
    public void splitTestsSingleCharacterStrings() {
        makeSplitter(single);

        assertEquals("split the string consisting of 1 character",
            "a",
            splitter.getRow(0,1));

        assertEquals("split the string consisting of 1 character, " +
                "but ask for two characters, " +
                "the string containing only a single char " +
                "should be returned","a", splitter.getRow(0,2));

    }

    @Test
    public void splitTestsTwoChars() {
        makeSplitter(twoChars);
        assertEquals("Row #0 of the ab string in 1 column rows",
            "a", 
            splitter.getRow(0,1));

        assertEquals("Row #1 of the ab string in 1 column rows",
            "b",
            splitter.getRow(1,1));

        assertEquals("Row #0 of the ab string in 2 column rows",
            "ab",
            splitter.getRow(0,2));

        assertEquals("Row #1 of the ab string in 4 column rows " 
            +"should return a blank string",
            "",
            splitter.getRow(1,4));

        assertEquals("Row #0 of the ab string in 4 column rows " 
            +"should return the ab string",
            twoChars, 
            splitter.getRow(0,4));

    }


    @Test
    public void splitTestsManyChars() {
        //split the alphabet into rows of 4 characters, return row 3
        //Expect "mnop"
        makeSplitter(manyChars);
        assertEquals("Row #3 of the alphabet in 4 column rows",
            "mnop",
            splitter.getRow(3,4));

        assertEquals("Row #0 of the alphabet in 4 column rows",
            "abcd", 
            splitter.getRow(0,4));

        assertEquals("Row #0 of the alphabet in 26 column rows",
            manyChars, 
            splitter.getRow(0,26));

        assertEquals("Row #0 of the alphabet in 26 column rows",
            "z",
            splitter.getRow(1,25));

        assertEquals("Row #0 of the alphabet in 27 column rows" 
            + " since the alphabet has 26 characters "
            + "it would be nice to get what we have", manyChars,
           splitter.getRow(0,27));
    }


    private void makeSplitter(String subject){
        splitter = new SplitStringUtility(subject);
    }


}

String SomeLongString = JavaAPIMethodFor (String[] strings, String delimeter)

2 Answers2