int a[][]={{1,1,2,4,6}, 
               {3,7,6,5,4}, 
               {5,6,5,4,3}, 
               {56,34,56,78,21}}; 

//twoweishuzu.java
public class twoweishuzu
{ public static void main( String args[])
{ int a[][]={{1,1,2,4,6},
               {3,7,6,5,4},
               {5,6,5,4,3},
               {56,34,56,78,21}};
int i,j;
for(i=0;i <a.length();i++)//这里用数组长度比较清晰,并且方便以后的修改
{for(j=0;j <a[i].length();j++)//同上.
System.out.print(a[i][j] + " ");
System.out.println();
}
}
}