一个实现排列和组合的JavaBean

mytest.java:
package customers;
public class mytest
{String[] mychar=new String[50];
 int charcount;
 int charlist;
 public void SetMyTest()
 //初始化
 {charcount=0;
charlist=1;
 }
 public void insertChar(String thischar)
 //增加新的字符串
 {charcount++;
mychar[charcount]=thischar;
charlist*=charcount;
 }
 public String listAllChar()
 //列出全排列
 {String[][] allchar=new String[charlist+1][charcount+1];
int i;
int j;
int z=1;
for (i=1;i<=charcount;i++)
{myCopy(addCharList(i,allchar,z),allchar,charlist,charcount);
 z*=i;
}
String listallchar=new String("");
for (i=1;i<=charlist;i++) 
{for (j=1;j<=charcount;j++)
 listallchar+=allchar[i][j]+" ";
 listallchar=listallchar+"<BR>";
}
return listallchar;
 }
 public String[][] addCharList(int i,String[][] allchar,int z) 
 //在i-1个对象的全排列中引入第i个对象
 {int j;
int h=1;
int k;
String[][] tempallchar=new String[charlist+1][charcount+1];
for (k=1;k<=z;k++)
{for (j=1;j<=i;j++)
 {myCopy(tempchar(j,allchar[k],mychar[i]),tempallchar[h],charcount);
h++;
 }
}
return tempallchar;
 }
 public String[] tempchar(int i,String[] beginchar,String thischar)
 //将新对象插入指定位置
{int j;
String[] tempbeginchar=new String[charcount+1];
myCopy(beginchar,tempbeginchar,charcount);
for (j=charcount;j>i;j--) tempbeginchar[j]=tempbeginchar[j-1];
tempbeginchar[i]=thischar; 
return tempbeginchar;
 }
 public String selectSomeChar(int select)
 //列出其中取出select个对象的全部组合
 {int selectcount=1;
int i;
for (i=select+1;i<=charcount;i++) selectcount=selectcount*i/(i-select);
String[][] selectchar=new String[selectcount+1][select+1];
int[][] selectint=new int[selectcount+1][select+1];
for (i=1;i<=select;i++) 
{selectchar[1][i]=mychar[i];
 selectint[1][i]=i;
}
int z=1;
addSelect(selectchar,selectint,1,select,select);
int j;
String selectsomechar=new String("");
for (i=1;i<=selectcount;i++) 
{for (j=1;j<=select;j++)
 selectsomechar+=selectchar[i][j]+" ";
 selectsomechar=selectsomechar+"<BR>";
}
return selectsomechar;
 }
 public void addSelect(String[][] selectchar,int[][] 
 selectint,int z,int position,int select)
 //增加新的组合
 {int i;
 if (position==select)
 {if (selectint[z][position]<charcount)
 {z++;
myCopy(selectint[z-1],selectint[z],select);
selectint[z][select]++;
for (i=1;i<=select;i++) selectchar[z][i]=mychar[selectint[z][i]];
addSelect(selectchar,selectint,z,position,select);
 }
else
 {position--;
addSelect(selectchar,selectint,z,position,select);
 }
 }
else
 {if (selectint[z][position]<charcount-select+position)
 {selectint[z][position]++;
selectint[z][position+1]=selectint[z][position]+1;
position++;
addSelect(selectchar,selectint,z,position,select);
 }
else
 {if (position==1)
 {return;
 }
else
 {position--;
addSelect(selectchar,selectint,z,position,select);
 }
 }
 }
 }
 public void myCopy(String[][] Str1,String[][] Str2,int i,int j)
 {int h;
int k;
for (h=1;h<=i;h++) for (k=1;k<=j;k++) Str2[h][k]=Str1[h][k];
 }
 public void myCopy(String[] Str1,String[] Str2,int i)
 {int h;
for (h=1;h<=i;h++) Str2[h]=Str1[h];
 }
 public void myCopy(int[] Str1,int[] Str2,int i)
 {int h;
for (h=1;h<=i;h++) Str2[h]=Str1[h];
 }
}