J2ME - 如何将double转换为字符串而无需10次表示(E-05)

Question

我有双重价值.我希望将它存储在带有E表示法的String中(在J2ME中)

例

双倍价值6.887578324E9想要显示为6887578342

Answer 1

您可以创建自己的方法来执行此操作,也可以使用一些现有的库.例如,Javolution为您提供了类和方法TypeFormat.format(double d,int digits,boolean scientific,boolean showZero,Appendable a)Check Javolution,它有很多很好的实用程序,但是如果你需要的只是格式化数字,只需编写自己的方法.这是对大数字的快速破解

    private static String nosci(double d) {
    if(d < 0){
        return "-" + nosci(-d);
    }
    String javaString = String.valueOf(d);
    int indexOfE =javaString.indexOf("E"); 
    if(indexOfE == -1){
        return javaString;
    }
    StringBuffer sb = new StringBuffer();
    if(d > 1){//big number
        int exp = Integer.parseInt(javaString.substring(indexOfE + 1));
        String sciDecimal = javaString.substring(2, indexOfE);
        int sciDecimalLength = sciDecimal.length();
        if(exp == sciDecimalLength){
            sb.append(javaString.charAt(0));
            sb.append(sciDecimal);              
        }else if(exp > sciDecimalLength){
            sb.append(javaString.charAt(0));
            sb.append(sciDecimal);
            for(int i = 0; i < exp - sciDecimalLength; i++){
                sb.append('0');
            }
        }else if(exp < sciDecimalLength){
            sb.append(javaString.charAt(0));
            sb.append(sciDecimal.substring(0, exp));
            sb.append('.');
            for(int i = exp; i < sciDecimalLength ; i++){
                sb.append(sciDecimal.charAt(i));
            }
        }
      return sb.toString();
    }else{
        //for little numbers use the default or you will
        //loose accuracy
        return javaString;
    }       


}