Initial data commit

Task/File-extension-is-in-extensions-list/Java/file-extension-is-in-extensions-list-1.java

@@ -0,0 +1,33 @@
+import java.util.Arrays;
+import java.util.Comparator;
+
+public class FileExt{
+	public static void main(String[] args){
+		String[] tests = {"text.txt", "text.TXT", "test.tar.gz", "test/test2.exe", "test\\test2.exe", "test", "a/b/c\\d/foo"};
+		String[] exts = {".txt",".gz","",".bat"};
+		
+		System.out.println("Extensions: " + Arrays.toString(exts) + "\n");
+		
+		for(String test:tests){
+			System.out.println(test +": " + extIsIn(test, exts));
+		}
+	}
+	
+	public static boolean extIsIn(String test, String... exts){
+		int lastSlash = Math.max(test.lastIndexOf('/'), test.lastIndexOf('\\')); //whichever one they decide to use today
+		String filename = test.substring(lastSlash + 1);//+1 to get rid of the slash or move to index 0 if there's no slash
+		
+		//end of the name if no dot, last dot index otherwise
+		int lastDot = filename.lastIndexOf('.') == -1 ? filename.length() : filename.lastIndexOf('.');
+		String ext = filename.substring(lastDot);//everything at the last dot and after is the extension
+		
+		Arrays.sort(exts);//sort for the binary search
+		
+		return Arrays.binarySearch(exts, ext, new Comparator<String>() { //just use the built-in binary search method
+			@Override                                                //it will let us specify a Comparator and it's fast enough
+			public int compare(String o1, String o2) {
+				return o1.compareToIgnoreCase(o2);
+			}
+		}) >= 0;//binarySearch returns negative numbers when it's not found
+	}
+}

Task/File-extension-is-in-extensions-list/Java/file-extension-is-in-extensions-list-2.java

@@ -0,0 +1,6 @@
+public static boolean extIsIn(String test, String... exts){
+	for(int i = 0; i < exts.length; i++){
+		exts[i] = exts[i].replaceAll("\\.", "");
+	}
+	return (new FileNameExtensionFilter("extension test", exts)).accept(new File(test));
+}