方法:
    public void insertUbalance() throws Exception{
        float b = Float.parseFloat(JOptionPane.showInputDialog("请输入此此用户余额(必填)"));
        float temp;
        temp = b;
        String s = Float.toString(b);
       
        if(s.equals("")){
            throw new Exception("余额不能为空");
        }
        else{
            int flagNum = 0;
            int flagdt = 0;
        for(int i = 0; i < s.length(); i++){
            if(Character.isLetter(s.charAt(i))){
                flagNum++;
            }
            if(s.charAt(i) == '.'){
                flagdt++;
            }
        }
        if(flagNum > 0){
            throw new Exception("余额不能包含非数字字符");
            //break;
        }
        if(flagdt > 1){
            throw new Exception("余额中,不能有两个.");
            //break;
        }
        me.setUbalance(temp);
        }
 
     }
调用:
try{
            //insertUid();
            //insertUcardId();
            //insertUname();
            //insertUadress();
            //insertUtelephone();
            //insertUemai();
            insertUbalance();
            
        }catch(Exception e){
            flag = false;
        } 
请问这样有哪里不对,高手指点!!