文字列を桁数で区切る

PG

public static final int array[][] =
    {
        {0,4},
        {4,9},
        {9,12},
        {12,15}
    };
public void test3() {


    	String mojiretsu = "12あ41 345 23111";
    	String conv = "";
        for(int i = 0; i<array.length; i++){
        	int mae = 0;
        	int ushiro = 0;
            for(int j = 0; j<array[i].length; j++){
            	if(j == 0) {
            		mae = array[i][j];
            	}else {
            		ushiro = array[i][j];
            	}
            }
            System.out.println(mojiretsu.substring(mae, ushiro));
        }
}

結果

12あ4
1 345
 23
111