java - SpannableString#setSpan 设置错误的文本范围

Question

我使用以下代码，它将错误的文本范围包装为粗体

    final StyleSpan span = new StyleSpan(BOLD);
    SpannableString ss = new SpannableString("line 1\nline 2");
    Log.d(getPackageName(), String.valueOf(ss.charAt(12)));
    ss.setSpan(span, 7, 12, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    ((TextView) findViewById(R.id.text)).setText(ss);

结果如下:

我很困惑ss.charAt(12)返回'2'，但是setSpan，当我setSpan与end“12”时，span不包括“2”

Answer 1

我发现setSpan(span, start, end, flag)，“start”是第一个字符索引，“end”是“最后一个字符索引+ 1”，我不知道这是错误还是预期

    final ForegroundColorSpan span = new ForegroundColorSpan(Color.RED);
    SpannableString ss = new SpannableString("line 1\nline 2");
    Log.d(getPackageName(), String.valueOf(ss.charAt(12)));
    ss.setSpan(span, 0, 13, 0);
    ((TextView) findViewById(R.id.text)).setText(ss);

我猜 setSpan 使用 String#substring:

 * @param      beginIndex   the beginning index, inclusive.
 * @param      endIndex     the ending index, exclusive.
 * @return     the specified substring.
 * @exception  IndexOutOfBoundsException  if the
 *             {@code beginIndex} is negative, or
 *             {@code endIndex} is larger than the length of
 *             this {@code String} object, or
 *             {@code beginIndex} is larger than
 *             {@code endIndex}.
 */
public String substring(int beginIndex, int endIndex) {