### Question:
OffByOne implements CharacterComparator { @Override public boolean equalChars(char x, char y) { return (Math.abs((int) x - (int) y) == 1); }  @Override boolean equalChars(char x, char y);  }### Answer:
@Test public void testequalChars1() { assertTrue(offByOne.equalChars('a', 'b')); }
@Test public void testequalChars2() { assertFalse(offByOne.equalChars('a', 'c')); }
@Test public void testequalChars3() { assertTrue(offByOne.equalChars('&', '%')); }
@Test public void testequalChars4() { assertFalse(offByOne.equalChars('a', 'B')); }