二维数组的遍历 能否解释一下 这个程序的运行过程 i<book.length是什么j<book[i].length这个又是指哪个长度
public static void main(String[] args) {
// TODO Auto-generated method stub
String[][] book=new String [4][2];
book[0]=new String[]{"红楼梦","曹雪芹"};
book[1]=new String[]{"三国演义","罗贯中"};
book[2]=new String[]{"水浒传","施耐庵"};
book[3]=new String[]{"西游记","吴承恩"};
for(int i=0;i<book.length;i++)
{
for(int j=0;j<book[i].length;j++)
{
System.out.print(book[i][j]+" ");
}
System.out.println();
}
}