public String toString$()$

Returns a String representing the characters stored in grid in a format that is

easy to read, that exactly matches the format given below.

o $($new LetterCrush$(4,3,$"AACADBBDCD"$)).$toString$()$ must return

Note the row number at the end of the $2^{nd}$ to $4^{th}$ lines, and the column numbers in

the last row. The column indices will always be one$-$digit values $($grids with widths

greater than nine will not be tested$).$

public boolean isStable$()$

Returns false if there is any position in grid where a non$-$EMPTY character is

above an EMPTY character $($a grid entry with a smaller row than a grid entry with

a larger row in the same column $-$ thus, for the example given above in the

description of the toString$()$ method, isStable$()$ would return false$).$

Otherwise, returns true.public boolean remove$($Line theLine$)$

Returns false if theLine is not a valid line, i$.$e$.$ if the line's start or end points are

not within the grid. For example, if grid has $3$ rows and $4$ columns, theLine starts

at row $1,$ column $1$ and it ends at row $1,$ column $5$ then method remove must

return false as part of theLine is not within the array grid. Recall that in a two$-$

dimensional array the first row has index $0$ and the first column also has index $0.$

If theLine is valid, this method replaces with EMPTY the entries in grid

corresponding to theLine. And then it returns true. For example, if grid has $3$ rows

and $4$ columns and the Line starts at row $1,$ column $1,$ and it ends at row $1,$

column $2,$ then the entries of grid in row $1,$ columns $1$ and $2$ are replaced with

EMPTY and the method returns true.