I explain:
I have a String in Java :
String numero = "59.2348837";
this is what I'm trying to do:
String.format( "%.2f", numero)
And I try to get as a result:
String resultado = "59.23";
But it throws me an error because number is String . The error jumps when I do string format .
How could you format that String to 2 decimals and that the result
remains a String ?
marks you error "number is String", since you need to convert the String to a numeric value, you can do it in this way converting the value of String to Double or Float by Double.parseDouble(numero) or through Float.parseFloat(numero) :
String numero = "59.2348837";
String resultado = String.format( "%.2f", Float.parseFloat(numero));
There is a similar question
but in this case you can convert the value of String to Double by Double.parseDouble(numero) , example:
String numero = "59.2348837";
DecimalFormat df = new DecimalFormat("0.00");
String resultado = df.format(Double.parseDouble(numero));
result will have the value:
59.23
You can even use a method with the above described to obtain the value you require:
private static String getTwoDecimals(String valor){
DecimalFormat df = new DecimalFormat("0.00");
return df.format(Double.parseDouble(valor));
}
and you call it this way:
String numero = "59.2348837";
String resultado = getTwoDecimals(numero);
to obtain as a result value:
59.23
It's because the %.2f format is allowed for float. To format them you will have to convert the string to float and then format it:
String numero = "59.2348837";
String result = String.format( "%.2f", Float.parseFloat(numero)); // <- convertiendo el string a float
System.out.println(result); // 59.23
The problem you are having is that in the format string, you are telling the String.format() method that what you will receive as the first parameter is a floating number and when you pass it a String you should throw a similar exception to this:
'java.util.IllegalFormatConversionException: f != java.lang.String'
To solve this, you only have to convert your string to a floating number (float or double) and pass that number to the method. This way it helps you:
String numero = "59.2348837";
String numeroFormateado = String.format("%.2f", Double.parseDouble(numero));
If you only want 2 decimals you can also do a substring so you save the double pairing of String to double and double to String
I'll give you a quick example:
// Aqui tenemos el número
String numero = "100.9988"
// Despues obtenemos la posición del punto
int posicionPunto = numero.indexOf('.');
// Seguidamente coges solo lo que te interesa del String desde el inicio hasta los2 decimales
// Le sumamos 3 a posicionPunto para que avance 3 posiciones (1 Punto y 2 Decimales)
resultado = numero.subString(0,posicionPunto+3)