names.length 和 names[].length

names.length是names数组的长度(大)

names[i].length是names数组中包含数组的长度（小）

String[][]   names={{"tom","jack","mike"},{"zhangsan","lisi","wangwu"}};   names.length 长度有2, {"tom","jack","mike"}和{"zhangsan","lisi","wangwu"}  

 names[1].length 其中  names[1]是{"tom","jack","mike"}，长度有3.