I need to create a random string which should be between the length of 6 to 10 but it sometimes generates only about the length of 3 to 5. Here's my code. Can anyone would be able to find out the problem? :(

            int lengthOfName = (int)(Math.random() * 4) + 6;
        String name = "";
        /* randomly choosing a name*/
        for (int j = 0; j <= lengthOfName; j++) {
            int freq = (int)(Math.random() * 100) + 1;
            if(freq <= 6){
                name += "a";
            }if(freq == 7 && freq == 8){
                name += "b";
            }if(freq >= 9 && freq <= 11){
                name += "c";
            }if(freq >= 12 && freq <= 15){
                name += "d";
            }if(freq >= 16 && freq <= 25){
                name += "e";                        
            }if(freq == 26 && freq == 27){
                name += "f";
            }if(freq == 28 && freq == 29){
                name += "g";
            }if(freq >= 30 && freq <= 33){
                name += "h";
            }if(freq >= 34 && freq <= 48){
                name += "i";
            }if(freq == 49 && freq == 50){
                name += "j";
            }if(freq >= 51 && freq <= 55){
                name += "k";
            }if(freq >= 56 && freq <= 60){
                name += "l";
            }if(freq == 61 && freq == 62){
                name += "m";
            }if(freq >= 63 && freq <= 70){
                name += "n";
            }if(freq >= 71 && freq <= 75){
                name += "o";
            }if(freq == 76 && freq == 77){
                name += "p";
            }if(freq == 78){
                name += "q";
            }if(freq >= 79 && freq <= 84){
                name += "r";
            }if(freq == 85 && freq == 86){
                name += "s";
            }if(freq == 87 && freq == 88){
                name += "t";
            }if(freq >= 89 && freq <= 93){
                name += "u";
            }if(freq == 94){
                name += "v";
            }if(freq == 95 && freq == 96){
                name += "w";
            }if(freq == 97){
                name += "x";
            }if(freq == 98 && freq == 99){
                name += "y";
            }if(freq == 100){
                name += "z";
            }
        }