Please help me, will need to get these expecte output in Java. You may not use Arrays nor ArrayLists for this.

public static String getVerticalBars(int maxRows, int maxCols, int bars, char color1, char color2, char color3) - This method returns a string with a number of vertical bars that correspond to the bars parameter. To compute the size of each vertical bar, divide maxCols by the specified number of bars. The first vertical bar will use color1, the second color2, and the third color3. If more than 3 bars are present, we will start again with color1. If the computed size for a vertical bar is less than 1, or any of the colors is invalid, the method will return null and no diagram will be generated. The method MUST not rely on System.out.println(). For example, calling DrawingApp.getVerticalBars(10, 12, 3, 'R', 'G', 'B'); will generate the string: RRRRGGGGBBBB RRRRGGGGBBBB RRRRGGGGBBBB RRRRGGGGBBBB RRRRGGGGBBBB RRRRGGGGBBBB RRRRGGGGBBBB RRRRGGGGBBBB RRRRGGGGBBBB RRRRGGGGBBBB 1 RRGGBBRRGGBB 2 RRGGBBRRGGBB 3 RRGGBBRRGGBB 4 RRGGBBRRGGBB 5 RRGGBBRRGGBB 6 RRGGBBRRGGBB 7 RRGGBBRRGGBB 8 RRGGBBRRGGBB 9 RRGGBBRRGGBB 10 RRGGBBRRGGBB 1 RRGGBBRRGG 2 RRGGBBRRGG 3 RRGGBBRRGG 4 RRGGBBRRGG 5 RRGGBBRRGG 6 RRGGBBRRGG 7 RRGGBBRRGG 8 RRGGBBRRGG 9 RRGGBBRRGG 0 RRGGBBRRGG|