月夜star的博客Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: Cannot invoke "javax.swing.JComboBox.getSelectedItem()" because "this.bookType" is null
非@跃的博客/错误,报异常:Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException。//错误,报异常:Exception in thread "AWT-EventQueue-0"drawTank(enemy.getX(),enemy.getY(),g,enemy.getDirect(),0);//...