import static org.junit.Assert.*;
import org.junit.Test;
public class StringToolsTest {
	static final char [] data = {0xca, 0xfe, 0xeb, 0xab, 0xee};
	static final String string5 = String.valueOf(data);
	static final String string0 = "";
	static final String string1 = "a";
	static final String string9 = "987654321";
	
	@Test
	public void testFillBackwards() {
		long l = 0;
		assertEquals(0xcafeebabeeL, StringTools.fillBackwards(string5, l));
		assertEquals(0L, StringTools.fillBackwards(string0, l));
		assertEquals(0x61L, StringTools.fillBackwards(string1, l));
		assertEquals(0x3837363534333231L, StringTools.fillBackwards(string9, l));
	}
}
public class StringTools {
	public static long fillBackwards(String s, long d)
	{
		long result = 0L;
		byte[] bytes = s.getBytes();
		for (int i=0; i<Math.min(8,bytes.length); i++){
			result |= ((bytes[bytes.length-i-1] & 0xff) << (8*i));
		}
		return result;
	}
}
Solution bellow (highlight to show):
The problem is on the line 29 in "& 0xFF". I should be doing &0xFFL instead. Why ? bytes[x]&0xff is by default int (both operands are widened to int), but then << is applied, result of which is type of left operand (java spec)  and this is  |= to long result. Solution is to make & operator to work on long values by adding L to 0xFF.
Puzzler on snipplr.
 
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