相乘字符串？

Question

So,i have those :

String[] pret = new String[allcant.size()];
String[] totaluri = new String[allcant.size()];
String[] cant = new String[allcant.size()];

I want to do something like this :

totaluri[l]=pret[l]*cant[l];`

but i can't.I guess i have to make them float? since my input from the edittexts that get the values in the cant and pret are decimals? How can i do that ? I tried this but it won't let me

totaluri[l]=Float.parseFloat(cant[l]) *Float.parseFloat(pret[l]);

Answer 1

You need to use Double.parseDouble() or Float.parseDouble() to convert a String to a numerical value with a decimal fraction. You can then use Double.toString() or Float.toString() to convert the result of your calculation back to a `String.

Putting this all together:

double temp = Double.parseDouble(cant[l]) * Double.parseDouble(pret[l]);
totaluri[l] = Double.toString(temp);

I strongly suggest that you read Primitive Data Types and Lesson: Numbers and Strings from Oracle's Java Tutorial for more information about using String s and Java's primitive data types.

Answer 2

BigDecimal pretBD = BigDecimal.valueOf(pret[i]);
BigDecimal cantBD = BigDecimal.valueOf(cant[i]);
BigDecimal totaluriBD = pretBD.multiply(cantBD).setScale(2);  // Decimals #.##

totaluri[i] = totaluriDB.toString();

It is much typing, and no operators (multiply, add), but double is for financial purposes inadequate. 5000 * 0.2 will not be 1000.0.

Answer 3

那这个呢？

totaluri[l] = new String(Float.parseFloat(cant[l]) * Float.parseFloat(pret[l]));