I am creating a simple program that performs simple math functions on the values a user enters in the EditText views. The first two EditText views contain integers and the last could be a decimal, thus the answer could also need to be in decimal form so I set the and (vis) as a double, but how can I limit the decimal places to four? Everything is running fine, the answer is just many decimal places long!
Here is my code:
public void onClick(View v) {
String a,b,t;
double vis;
EditText txtbox1 = (EditText)findViewById(R.id.A);
EditText txtbox2 = (EditText)findViewById(R.id.B);
EditText txtbox3 = (EditText)findViewById(R.id.t);
TextView tv = (TextView) findViewById(R.id.Answer);
a = txtbox1.getText().toString();
b = txtbox2.getText().toString();
t = txtbox3.getText().toString();
vis = ((Integer.parseInt(a)*1) + (Integer.parseInt(b)*2)) / (Double.parseDouble(t));
tv.setText(double.toString(vis));
}
}
Thanks so much!
You could use String.format() to make sure you only get 4 decimal places in your output. Simply replace the last line with tv.setText(String.format("%.4f", vis));.
See http://download.oracle.com/javase/tutorial/java/data/numberformat.html for more details on how to use String.format() for this purpose.
I think it's a bit too late to answer, but it may help for future purpose.
If we have a double number and we need to get the 4 decimal values we can multiply the double by 10000, and cast the double value into an integer and reverse into double again and divide the digit by 10000.
For more control, use BigDecimal.round(). You can set a MathContext with the precision and rounding rule you require (.5 is round up, vs .5 is rounded down, etc).
double vis = 21.23456;
tv.setText(new BigDecimal(vis).round(new MathContext(6, RoundingMode.HALF_UP)).toString());
Related
I am trying to make a BMI application. When I run the application the BMI values are displayed in numeral form that I don't understand. I have tried both Float and Double type but results are same.
For example:
Height (m): 2
Weight (Kg): 100
BMI is displayed as : 2.0E-4 instead of 25
The part of the code that effects this is:
String editText1= height_field.getText().toString();
String editText2= weight_field.getText().toString();
try { // Parse string to int
double height = Double.parseDouble(editText1);
double weight = Double.parseDouble(editText2);
double bmi_result = (weight/(height*height));
String bmi_text = Double.toString(bmi_result);
display.setText(bmi_text);
System.out.println("OnClick: computeButton is clicked");
}
catch(NumberFormatException nfe) {
alert.show(); // Show error alert
To answer your original question, you should be using java.text.DecimalFormat, something like:
DecimalFormat formatter = new DecimalFormat("##.##");
display.setText(formatter.format(bmi_result));
Will force the result to be in the format of two digits followed by two decimal points, the table in the link above shows how to generate that.
However, since 2.0E-4 is 0.0002, I think Jon Skeet's comment is correct: You're doing your math operation wrong, since the value you're printing is a very small fraction of 25 :)
I'd recommend using Log.v() to print out your math operation before you actually do it, so you can see what the values of weight and height actually are, I highly doubt they're correctly set at what you described in the question.
I can't seem to get my head around this. If have tried the following approaches:
DecimalFormat df = new DecimalFormat("00000.00");
DecimalFormat df = new DecimalFormat("######.##");
But the following line always generates and IllegalArgumentException.
double price = Double.valueOf(df.format(((EditText) view
.findViewById(R.id.edit_item_price)).getText().toString()));
// Sample input passed is value of 200 or some other whole number.
item.setPrice(price);
It doesn't make sense as I only copied the obvious solutions in this forum. Most of you got the format() to work.
Originally, I didn't have these lines of code. I just call my setPrice() method after getting the item price. This works. However, Double.valueOf() has a nasty habit of using only one decimal position.
e.g. passed 200. I get 200.0 inside my item object. I figured by using DecimalFormat I could've prevented this but it appears this caused me MORE headaches instead.
When you say you pass 200 and you get 200.0, you mean you get it in a double value? If so, that doesn't matter - it's a number and 200 = 200.0 for double values.
format(...) turns a double value to a String value. You have it the other way round. That's why you get the Exception.
If the price variable is actually a double you should do
double price = Double.valueOf(((EditText) view
.findViewById(R.id.edit_item_price)).getText().toString())
But I think you want that the price is a String, then you should convert the text from the EditText to a double and that double back to a String with something like new DecimalFormat("0.00")
I want to approximate a number showing only two digits after the decimal point.
I wrote this:
String result = String.valueOf(new BigDecimal(price).setScale(4, BigDecimal.ROUND_UP).doubleValue());
If price is a decimal number like 63,9222, it works fine. But If price is ,for example, equal to 7.00, is printed 7.0 .
I tried to use RoundingMode.CEILING instead of BigDecimal.ROUND_UP , but it didn't work and i don't know why. Maybe it will be better to use Double instead of BigDecimal?
Use String.format
double myValue = new BigDecimal(price).setScale(4, BigDecimal.ROUND_UP).doubleValue());
String result = String.format(Locale.ENGLISH, "%.2f", myValue);
iam allmoust done with my app but iam stuck on this thing , i have two int's
called "positive" and "negative" and when i procces source below it shows 0.0
total = positive + negative;
float rate = positive/total;
rate*=100;
TextView analitycs = (TextView)v.findViewById(R.id.app_scores_analitycs);
analitycs.setText(String.valueOf(rate));
What Victor said is true.
Also you might want to use something different than String.valueOf(rate) to set the text of your text view, because this method can give you an ugly representation of the number.
You should probably use String.format("%.2f", rate) ad tweak that to your needs.
Are positive and total floats/doubles?
If not, then an int/int will give you an int.
The solution would be to cast either positive or negative as a float.
try the following:
float rate = ((float)(positive))/total;
First of all please excuse me for my bad English speaking.
I am new to Android Development. I have a problem and think you can solve it.
The problem is:
I have a very big double value like 12345678987654321 in my android app
but when i want to show it on EditText, it will be shown like this 12345678987654300.
In this case when my value characters is over than 15 chars android shows remaining chars with "0"
i don't know what i have to to do.
i am using this code:
DecimalFormat df = new DecimalFormat("#.#########");
double a = Distancevals[1] * Distancevals[2];
//Distancevals is an array of double with big values
EditText editto = (EditText)findViewById(...);
editto.setText(df.format(a));
Double stores your number 12345678987654321 in format 1.23456789876543E16, so you lose the end of the number 21. When you format the result it's known that your number consists of 17 signs, so format function adds two zeros in the end of your number instead of 21.
Try to use this:
DecimalFormat df = new DecimalFormat("#.#########");
BigDecimal a = new BigDecimal(Distancevals[1] * Distancevals[2]);
// Distancevals is an array of double with big values
EditText editto = (EditText) findViewById(...);
editto.setText(df.format(a));
Try this one
DecimalFormat df= new DecimalFormat("###############00");
double a=Distancevals[1]*Distancevals[2];
//Distancevals is an array of double with big values
EditText editto=(EditText)findViewById(...);
editto.setText(df.format(a));
You just show it as editto.setText(a+"");
Cause in your case EditText is not doing anything but DecimalFormat is changing your number.
I suggest that in the line:
editto.setText(df.format(a));
Change it to:
editto.setText(df.format(a.toString()));