flutter 控制显示文本显示数量多出省略

`````

///  char 目标字符串   lengths 期望长度

String omitCharacter(String char, int lengths) {
  if (char.runtimeType != String) {
    return '';
  }
  if (lengths.runtimeType != int) {
    return '';
  }
  if (char.length > lengths) {
    print(char.substring(0, lengths - 1) + '...');
    return char.substring(0, lengths - 1) + '...';
  } else {
    return char;
  }
}

``````