Java8--方法--StringBuilder--trim

=>builder: :/u1D56B

追加代码点
builder.appendCodePoint(58);
=> builder:       :/u1D56B:

替换代码点
builder.setCharAt(7, (char) 58);
=> builder:       :/u1D56::

插入字符串
StringBuilder builderinsert = builder.insert(5,"::");
=> builderdelete: :/u1D::56::
=> builder:       :/u1D::56::

删除指定范围代码点
StringBuilder builderdelete = builder.delete(4,builder.length());
=> builderdelete: :/u1
=> builder:       :/u1