Extract multiple substrings from a string in JAVA/Android

Question

In my Android application I have a large String containing the source of a webpage of mine. This webpage using javascript rotates a six transparent png's over the top of a few other png's. What I want to do is extract the last 4 characters of the png file names, but ONLY for the first 6 images that appear in the source code. These last 4 characters of each png file name are a time stamp that i need and want to read them into an array.

Source:

<html><head><style>html {background: black} body {background:black;margin:0;padding:0;}</style><script>setInterval('changeImage()',1000);function changeImage() {size = images.length;if (current == size-1) { current = -1;}current++;document.getElementById('rad').src = images[current];    }current = 0;images = new Array();images[0] = 'image.201105261318.png';images[1] = 'image.201105261323.png';images[2] = 'image.201105261330.png';images[3] = 'image.201105261336.png';images[4] = 'image.201105261342.png';images[5] = 'image.201105261348.png';</script></head><body><img style="position:absolute; top: 0px; left: 0px;z-index:1;" src="http://background.png"></body></html>

Desired output:

String Array = "1318,1323,1330,1336,1342,1348"

I have tried a lot of different substring retrieval methods, but still am struggling. I know how to identify the end of the string using ".png" but not sure how to say that i want just the 4 chars preceding that delimiter..?

Any help would be greatly appreciated.

Cheers

Greg

EDIT:

Got It!

int delimiter = source.indexOf(".png");
String imageTime1 = source.substring(delimiter-4,delimiter);
int delimiter2 = source.indexOf(".png",delimiter+4);
String imageTime2 = source.substring(delimiter2-4,delimiter2);
int delimiter3 = source.indexOf(".png",delimiter2+4);
String imageTime3 = source.substring(delimiter3-4,delimiter3);
int delimiter4 = source.indexOf(".png",delimiter3+4);
String imageTime4 = source.substring(delimiter4-4,delimiter4);
int delimiter5 = source.indexOf(".png",delimiter4+4);
String imageTime5 = source.substring(delimiter5-4,delimiter5);
int delimiter6 = source.indexOf(".png",delimiter5+4);
String imageTime6 = source.substring(delimiter6-4,delimiter6);

Cheers

Cornelius Dol · Accepted Answer · 2011-05-28 02:37:19Z

1

Perhaps I am missing the point, but...

Given index x being the text.indexOf(".png"), you can simply use text.substring(x-4,x);.

Then you can do text.indexOf(".png",x+4) to get your next image end, and repeat the above.

If possible case variations are a concern you could change the entire string to upper or lower case before searching for your extension.

answered May 28, 2011 at 2:37

Cornelius Dol

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2 Comments

Pelly Over a year ago

Just curious though, how does "delimiter+4" move it to the next image in my string?

Cornelius Dol Over a year ago

@Pelly: It's indexOf, which commences at x+4. So the string is searched for the next ".png".

Haphazard · Accepted Answer · 2011-05-28 02:31:38Z

1

Once you have your list of images, do a String.split(';') to get a list of images[0] = 'image.201105261318.png' items. Then you can get the length of each item and take a String.substring(length-9,length-4) to get the last 4 characters of each item.

The substring code is untested but you can tweak it to get exactly what you need.

answered May 28, 2011 at 2:31

Haphazard

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