[Date类](Date%E7%B1%BB.md) [DateFormat类](DateFormat%E7%B1%BB.md) [Calendar类](Calendar%E7%B1%BB.md) [Math类](Math%E7%B1%BB.md) [String类](String%E7%B1%BB.md) [object类](object%E7%B1%BB.md) [System类](System%E7%B1%BB.md) [正则表达式](%E6%AD%A3%E5%88%99%E8%A1%A8%E8%BE%BE%E5%BC%8F.md) [BigInteger类](BigInteger%E7%B1%BB.md) [BigDecimal类](BigDecimal.md) [Arrays工具类](Arrays%E5%B7%A5%E5%85%B7%E7%B1%BB.md) [StringBuffer类](StringBuffer%E7%B1%BB.md) [基本类型包装类](%E5%9F%BA%E6%9C%AC%E7%B1%BB%E5%9E%8B%E5%8C%85%E8%A3%85%E7%B1%BB.md) [自动装箱和自动拆箱](%E8%87%AA%E5%8A%A8%E8%A3%85%E7%AE%B1%E5%92%8C%E8%87%AA%E5%8A%A8%E6%8B%86%E7%AE%B1.md)