swing - problem with loop- for: java -

i'm trying change code loop, have problems

panel[1].setbackground(color.red);             panel[2].setbackground(color.white);             panel[3].setbackground(color.red);             panel[4].setbackground(color.white);             panel[5].setbackground(color.red);             panel[6].setbackground(color.white);             panel[7].setbackground(color.red);             panel[8].setbackground(color.white);             panel[9].setbackground(color.red);             panel[10].setbackground(color.white); 

new code - for

for (int = 0; < panel.length; i++) {                 panel[(i*2)+1].setbackground(color.red);//i think correct, or no?                 panel[(i*3)+1].setbackground(color.white); //problem here             } 

thanks

solution

for (int = 1; < panel.length; i++) {     if ( % 2 == 0 ) { panel[i].setbackground(color.white); }     else { panel[i].setbackground(color.red); }    } 

or more concise expression using ternary operator:

for (int = 1; < panel.length; i++) {      panel[i].setbackground( % 2 == 0 ? color.white : color.red );   } 

explaination

% modulo operator, i % 2 == 0 when i even, != 0 when odd.

caveats

your array of panels referencing in example starts @ 1, arrays in java start @ zero, might have potential 1 off error here if have in (first) 0 array element.

using type safe list classes better working arrays directly, not have deal 1 off error problems creating not using first array slot.