我想循环我的代码时遇到问题，即使用户输入为真，它也会重复循环

Question

问题循环将一次又一次重复，即使用户输入为true

int D1 = 1;
    do{
    String N6 = JOptionPane.showInputDialog(null,"Enter Working Hours for Week 2","Working Hours",JOptionPane.QUESTION_MESSAGE);
        int D = Integer.parseInt(N6);
            if (D < 40 && (stat.equals("Full Time"))) {
                JOptionPane.showMessageDialog(null,"Full Timers Working Hours must be between 40 - 90 Hours !","Error",JOptionPane.WARNING_MESSAGE);
                D++;
            }
    } while ( D1 <= 1 );