Double.parseDouble丢失小数位

Question

I´ve encountered a problem that I can not solve. Tried various solutions described on the site with no result. I´m passing a string “ total ” that translates to 30.00 but on Doubleparse it changes to 30.0

I need the double to be 30.00 because it has to be added to an arraylist, and also displayed as text, as 30.00 and not as 30.0

I´ve tried

DecimalFormat df = new DecimalFormat("#.##");
Double number_total = Double.parseDouble(df.format(total));

ERROR: java.lang.IllegalArgumentException: Bad class: class java.lang.String at java.text.NumberFormat.format(NumberFormat.java:304) at java.text.DecimalFormat.format(DecimalFormat.java:702) at java.text.Format.format(Format.java:93) at com.example.jc.salesman.MainActivity.Totais(MainActivity.java:338) at com.example.jc.salesman.MainActivity$2.onClick(MainActivity.java:235)

String strSum = ((String.format("%.2f", Double.toString(sum))));

ERROR: Process: com.example.jc.salesman, PID: 26845 java.util.IllegalFormatConversionException: %f can't format
java.lang.String arguments at java.util.Formatter.badArgumentType(Formatter.java:1489) at java.util.Formatter.transformFromFloat(Formatter.java:2038) at java.util.Formatter.transform(Formatter.java:1465) at java.util.Formatter.doFormat(Formatter.java:1081) at java.util.Formatter.format(Formatter.java:1042) at java.util.Formatter.format(Formatter.java:1011) at java.lang.String.format(String.java:1999) at java.lang.String.format(String.java:1973) at

com.example.jc.salesman.MainActivity.Totais(MainActivity.java:368)

I even forced Locale in main,

Locale.setDefault(new Locale("en", "US"));

Please HELP :)

public void Total (String total){

    Log.d("log2","total: " + total);// it prints 30.00

    Double number_total = Double.parseDouble(total);

    Log.d("log2","number_total: " + total);// it prints 30.0
    losing a decimal place.

    array_Total.add (number_total); //Arraylist<Double
    sum (double) = sum + number_total;
    String strSum = (Double.toString(sum));
    total.setText (strSum);
}

Answer 1

You are using the df.format() wrongly. From the javadoc , the .format() method of DecimalFormat takes a Number (double, long or Object that is a subclass of Number).

What you can do is to parse and store the double normally(30.0). When you do need to output the double, you can output using String formatter eg String.format("%.2f", val)

Answer 2

Use String.format("%.2f", doubleValue) to set it to 2 decimal points. But it will roundoff your other decimal values to 2 decimal points(Eg: 30.2345 --> 30.23) as well so if you want to retain decimal values then do it conditionally.