ケツについたU+0000を落とすだけでいいなら
String str = new String(new byte[]{ 0x68, 0x6F, 0x67, 0x65, 0x66, 0x6F, 0x6F, 0x70, 0x69, 0x79, 0x6F, 0x00, 0x00, 0x00, 0x00, 0x00 }, "UTF-8");
str = str.replace("\0", "");