CODEWITHSUNDEEP
javahashmap
笑一笑不收錢
笑一笑不收錢

Reputation: 1

How to add item into HashMap by method

I want to add some item from the class DisplayCard to the hashMap displayCardMap by the method. The output of hashmap to look like

brand: modelNumber: memorySize

Then I create some method to help me. 

import java.util.*;

public class ComputerShop {

    Map <String, Double> displayCardMap = new HashMap <String, Double>();

    public void addDisplayCard(DisplayCard oneDisplayCard){
        displayCardMap.put(oneDisplayCard.getBrand() + ": " + oneDisplayCard.getmodelNumber(), oneDisplayCard.getmemorySize());
    }
}

public class DisplayCard {
    String brand;
    String modelNumber;
    double memorySize;

    //constructor method
    public DisplayCard(String brand, String modelNumber, double memorySize){
        this.brand = brand;
        this.modelNumber = modelNumber;
        this.memorySize = memorySize;
    }

    // getter method
    public String getBrand(){
        return brand;
    }

    public String getmodelNumber(){
        return modelNumber;
    }

    public double getmemorySize(){
        return memorySize;
    }
 }

But I get an error after I create a new item by the addDisplayCard()

public class TestComputerShop{
    public static void main(String[] args) {

        ComputerShop ashop = new ComputerShop();
        // call method
        ashop.addDisplayCard("ATI", "R9 390",6.0);

    } 
}

So I want to know what is the problem.

Should I create a new DisplayCard object first? Or the function is wrong at the beginning.

Upvotes: 0

Views: 49

Answers (1)

wake-0
wake-0

Reputation: 3966

you need to create a new DisplayCard object, because your method requires one:

public class TestComputerShop {
    public static void main(String[] args) {

        ComputerShop ashop = new ComputerShop();
        // call method
        ashop.addDisplayCard(new DisplayCard("ATI", "R9 390",6.0));

    } 
}

Another solution is to use method overloading inside the ComputerShop:

public class ComputerShop {

    Map <String, Double> displayCardMap = new HashMap <String, Double>();

    public void addDisplayCard(DisplayCard oneDisplayCard){
        displayCardMap.put(oneDisplayCard.getBrand() + ": " + oneDisplayCard.getmodelNumber(), oneDisplayCard.getmemorySize());
    }

    public void addDisplayCard(String brand, String modelNumber, double memorySize){
        this.addDisplayCard(new DisplayCard(brand, modelNumber, memorySize));
    }
}

Upvotes: 2

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