Remove string after second colon in Java

I would like to remove the string after the second colon and add a new string behind.

I have a maker when clicking on a marker I add the string using ALertDialog on the marker title so I can get those value to the process for a text file. But if I select that marker again I want to remove that text after colon so I don't add duplicate string again.

I checked this link but it uses a regular expression and I don't have any experience with that.

> My String = W:3:ER1,ER2,ER3,,,,

>Output = W:3

I would like to remove the string after the second colon so I can attach my string

Here is my onMarkerClick

      @Override
public boolean onMarkerClick(final Marker marker) {
final String[] title = {marker.getTitle()};
Bitmap smallDot = Bitmap.createScaledBitmap(getBitmapFromVectorDrawable(getApplicationContext(),
R.drawable.blue_dot), 15, 15, false);
final String[] selectedItems = {"", "", "", "", ""};
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle("Enable Relays");
// add a checkbox list
final String[] relays = {"Relay 1", "Relay 2", "Relay 3", "Relay 4", "Implement"};
boolean[] checkedItems = {true, false, false, true, false};
builder.setMultiChoiceItems(relays, null, new DialogInterface.OnMultiChoiceClickListener() {
@Override
public void onClick(DialogInterface dialog, int which, boolean isChecked) {
if (isChecked) {
// If the user checked the item, add it to the selected items
selectedItems[which] = "ER" + (which + 1);
} else if (!isChecked) {
// Else, if the item is already in the array, remove it
selectedItems[which] = "";
}
Toast.makeText(MainActivity.this, "" + Arrays.toString(selectedItems), Toast.LENGTH_LONG).show();
}
}).setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//                title[0] +=  ":" + selectedItems[0] + "," + selectedItems[1] + "," + selectedItems[2] + "," + selectedItems[3] + "," + selectedItems[4];
int commas = 0;
for (int i = 0; i < title[0].length(); i++) {
if (title[0].charAt(i) == ',') commas++;
}
if (!title[0].contains("ER1") && commas <= 4)
title[0] += ":" + selectedItems[0];
if (!title[0].contains("ER2") && commas <= 4)
title[0] += "," + selectedItems[1];
if (!title[0].contains("ER3") && commas <= 4)
title[0] += "," + selectedItems[2];
if (!title[0].contains("ER4") && commas <= 4)
title[0] += "," + selectedItems[3];
if (!title[0].contains("ER5") && commas <= 4)
title[0] += "," + selectedItems[4];
marker.setTitle(title[0]);
marker.showInfoWindow();
Toast.makeText(MainActivity.this, "" + title[0], Toast.LENGTH_LONG).show();
}
}).setNegativeButton("CANCEL", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
// create and show the alert dialog
AlertDialog dialog = builder.create();
dialog.show();
return true;
}

First we split on the last : to get the title.
Then we parse on , from the last : to get items and we filter out empty ones.

import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        String raw = "W:3:ER1,ER2,ER3,,,,";
        String title = raw.substring(0, raw.lastIndexOf(":"));
        String[] selectedItems = raw.substring(raw.lastIndexOf(":")+1).split(",");
        List<String> items = Arrays.asList(selectedItems).stream().filter(str ->
            ! "".equals(str)
        ).collect(Collectors.toList());


        System.out.println("Title "+ title);
        System.out.println("Items "+ items);
    }
}

Prints
> Title W:3
Items [ER1, ER2, ER3]

Edit 1 : Should handle single colon

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        String raw = "W:3";
        List<String> items;
        String title;
        if (raw.replaceAll("[^:]", "").length() > 1) { // String with every :
            title = raw.substring(0, raw.lastIndexOf(":"));
            String[] selectedItems = raw.substring(raw.lastIndexOf(":") + 1).split(",");
            items = Arrays.asList(selectedItems).stream().filter(str ->
                    !"".equals(str)
            ).collect(Collectors.toList());
        } else {
            title = raw;
            items = null;
        }


        System.out.println("Title "+ title);
        System.out.println("Items "+ items);
    }
}

And prints for raw = "W:3";
> Title W:3
Items null

I found the trick to remove string after the second colon.

First, find the position for the second colon. Then remove the string after that position.

Here the method for finding the position

private static int findSecondColonPosition(String s) {
int result = -1;
int dotsToFind = 2;
char[] ca = s.toCharArray();
for (int i = 0; i < ca.length; ++i) {
if (ca[i] == ':') --colonsToFind;
if (dotsToFind == 0) return i;
}
return result;
}

Here my updated onMarkerClick code

    @Override
public boolean onMarkerClick(final Marker marker) {
final String[] title = {marker.getTitle()};
Bitmap smallDot = Bitmap.createScaledBitmap(getBitmapFromVectorDrawable(getApplicationContext(),
R.drawable.blue_dot), 15, 15, false);
final String[] selectedItems = { "", "", "", ""};
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle("Enable Relays");
// add a checkbox list
final String[] relays = {"Relay 2", "Relay 3", "Relay 4", "Implement"};
builder.setMultiChoiceItems(relays, null, new DialogInterface.OnMultiChoiceClickListener() {
@Override
public void onClick(DialogInterface dialog, int which, boolean isChecked) {
if (isChecked) {
// If the user checked the item, add it to the selected items
selectedItems[which] = "ER" + (which + 2);
} else if (!isChecked) {
// Else, if the item is already in the array, remove it
selectedItems[which] = "";
}
Toast.makeText(MainActivity.this, "" + Arrays.toString(selectedItems), Toast.LENGTH_LONG).show();
}
}).setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
int secoundColonPosition = findSecondColonPosition(title[0]);
if (secoundColonPosition > 0) {
System.out.println("title after remove: " + title[0].substring(0, secoundColonPosition));
title[0] = title[0].substring(0, secoundColonPosition);
} else {
System.out.println("ERROR: there is not a 2nd colon in " + title[0]);
}
title[0] += ":" + selectedItems[0] + "," + selectedItems[1] + "," + selectedItems[2] + "," + selectedItems[3];
marker.setTitle(title[0]);
marker.showInfoWindow();
Toast.makeText(MainActivity.this, "" + title[0], Toast.LENGTH_LONG).show();
}
}).setNegativeButton("CANCEL", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
// create and show the alert dialog
AlertDialog dialog = builder.create();
dialog.show();
//        if (isEnable()) {
//            title += ":Enable_Implement";
//            marker.setTitle(title);
//            marker.setIcon(BitmapDescriptorFactory.fromBitmap(smallDot));
//            setEnable(false);
//            setDisable(true);
//            programStatusTextView.setText("Choose a stop actuation point");
//        } else if (isDisable()) {
//            title += ":Disable_Implement";
//            marker.setTitle(title);
//            marker.setIcon(BitmapDescriptorFactory.fromBitmap(smallDot));
//            setDisable(false);
//            programStatusTextView.setText("");
//        }
return true;
}