Thread: How to print output in 2 decimal points in java?

import java.io.*;
public class Main {

/**
* Make by Lee Jia Ren
*/
public static void main(String[] args) throws IOException
{
BufferedReader stdin = new BufferedReader (new InputStreamReader(System.in));

String blockNumber, flatNumber, name;
String str;
int unit;

System.out.print("Enter Your Block Number: ");
blockNumber = stdin.readLine();

System.out.print("\nEnter Your Flat Number: ");
flatNumber = stdin.readLine();

System.out.print("\nEnter Your Name: ");
name = stdin.readLine();

System.out.print("\nEnter Eletricity Unit: ");
str = stdin.readLine();
unit = Integer.parseInt(str);

EletricBillGenerator ebGen = new EletricBillGenerator();
ElectricBill eb = ebGen.getData(blockNumber, flatNumber, name, unit );
ElectricBill calcEB = ebGen.calc(eb);
ebGen.display(calcEB);
}

}



public class EletricBillGenerator {

public ElectricBill getData(String blockNumber, String flatNumber, String name, int unit){
ElectricBill eb = new ElectricBill();
eb.setBlockNumber(blockNumber);
eb.setFlatNumber(flatNumber);
eb.setName(name);
eb.setUnit(unit);

return eb;

}

public ElectricBill calc(ElectricBill inElecBill){

double billAmount;

if (inElecBill.getUnit() < 100)
{
billAmount = 0.40*inElecBill.getUnit();
}
else if (inElecBill.getUnit() < 300)
{
billAmount = 0.50*inElecBill.getUnit();
}
else
{
billAmount = 0.60*inElecBill.getUnit();
}

billAmount = billAmount>150?billAmount*1.15:billAmount;
inElecBill.setBillAmount(billAmount);

return inElecBill;

}

public void display(ElectricBill inElecBill){
System.out.println("");
System.out.println("");
System.out.println("\tElectricity Bill");
System.out.println("****************************** ************************");
System.out.println("\tName : " + inElecBill.getName());
System.out.println("\tUnits : " + inElecBill.getUnit());
System.out.println("\tTotal Charges : RM" +inElecBill.getBillAmount());
System.out.println("****************************** ************************");

}
}


public class ElectricBill {
private int unit;
private double billAmount;
private String blockNumber, flatNumber, name;

public String getBlockNumber() {
return blockNumber;
}
public void setBlockNumber(String blockNumber) {
this.blockNumber = blockNumber;
}
public String getFlatNumber() {
return flatNumber;
}
public void setFlatNumber(String flatNumber) {
this.flatNumber = flatNumber;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getUnit() {
return unit;
}
public void setUnit(int unit) {
this.unit = unit;
}
public double getBillAmount() {
return billAmount;
}
public void setBillAmount(double billAmount) {
this.billAmount = billAmount;
}
}

java.png

Originally Posted by DrakeLee

answer to 2 decimal place...

Here's the thing: Java makes it "easy" to print numbers if you don't care what they look like. If you want them formatted to a particular number of digits after the decimal point there are several ways.

One way is to use printf() instead of print() or println(). For your problem you need to know about the "%f" format specifier.

Here's some code that shows what I mean. Make a little demo program and put this in your main() method.

        double amount = 123.456789123;
 
        // Java println() picks a generic format that it considers appropriate
        // Prints as many digits as it needs
        //
        System.out.println("Method 1: Amount = " + amount);
 
        // Default printf("%f") will give six digits after the decimal point
        //
        System.out.printf("Method 2: Amount = %f\n", amount);
 
        // Specify a particular number of decimal places and
        // it will round off to that number.
        //
        System.out.printf("Method 3: Amount = %.2f\n", amount);

Output:

Method 1: Amount = 123.456789123
Method 2: Amount = 123.456789
Method 3: Amount = 123.46


Note that the print statements do not change the internal value of the variable, they just display it to your specifications.


Reference: Java Formatter Class

Now, serious applications involving decimal fractions of money are very likely not use floating point arithmetic at all, but for starters, rounding off a floating point number to a particular number of decimal places for printing can be done relatively painlessly with printf().


Cheers!

Z

Originally Posted by ShaunB

I didn't know you could use printf - I generally use System.out.format("%.2f", 1.234);

I don't know of any differences between the two. The Java Formatter Class documentation refers to both of them as "convenience methods." From that, I conclude (and observe) that there are various less-convenient ways...

public class Z {
    public static void main(String [] args) {
        double x = 1.234;
        System.out.format("Method 1: x = %.2f\n", x);
        System.out.printf("Method 2: x = %.2f\n", x);
    }
}

C programmers who have been sentenced to spend purgatory time on Planet Java tend to use printf. Java programmers with no baggage from previous incarnations tend to use whatever the heck they see in programming assistance forums like this.

As my dear old grannie used to say, "Chacun à son goût!"


Regards,

Dave