为什么我的方法不返回String？

Question

I am using a program class to try to test the methods in my object class to see if they work. It is a gas meter reading system and I am trying to deposit money to pay off some of the balance of what the customer owes.

My object class consists of:

package GasAccountPracticeOne;

public class GasAccountPracticeOne 

{
    private int intAccRefNo;
    private String strName;
    private String strAddress;
    private double dblBalance = 0;
    private double dblUnits;
    private double dblUnitCost = 0.02;

    public GasAccountPracticeOne(int intNewAccRefNo, String strNewName, String strNewAddress, double dblNewUnits)
    {
        intAccRefNo = intNewAccRefNo;
        strName = strNewName;
        strAddress = strNewAddress;
        dblUnits = dblNewUnits;

    }//end of constructor

    public GasAccountPracticeOne( int intNewAccRefNo, String strNewName, String `strNewAddress)
    {
        intAccRefNo = intNewAccRefNo;
        strName = strNewName;
        strAddress = strNewAddress;

    }//end of overloading contructor

    public String deposit(double dblDepositAmount)
    {
        dblBalance = dblBalance - dblDepositAmount;

        return "Balance updated";
    }

In my program class I have written:

        System.out.println("Enter deposit amount");
        dblDepositAmount=input.nextDouble();
        firstAccount.deposit(dblDepositAmount);

But in my object class in the deposit method I have asked for a string saying return "Balance updated" to be returned.

When I run the test there is no string returned. Banging my head off the table - have I done something ridiculous?

Answer 1

You did nothing to print your string:

1- use your output and print it:

System.out.println("Enter deposit amount");
dblDepositAmount=input.nextDouble();
String myString = firstAccount.deposit(dblDepositAmount); //<-- you store your string somewhere
System.out.println(myString ); // you print your String here

System.out.println(firstAccount.deposit(dblDepositAmount)); // Or you can show it directly

2- You can also make your method print the value

public void deposit(double dblDepositAmount)
{
    dblBalance = dblBalance - dblDepositAmount;

    System.out.println("Balance updated");
}

So when you call it, it will print by itself (returning a String value is useless in your case).

Answer 2

This line of code discards the result of invoking deposit method, therefore you do not see that string:

firstAccount.deposit(dblDepositAmount);

Try the following instead:

System.out.println(firstAccount.deposit(dblDepositAmount));