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Choco_Late
@Choco_Late (レート チョコ)

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コードのエラーが解けません。

Q&A

Closed

Java

解決したいこと

コードのエラーを解くことができません。
コードのエラーを解こうとして、深みにハマっています。

このコードは
Bank,Branch, Customer の三つのクラスと
Main クラスから構成されています。
AlleyListの学習をしています。
模範回答を見てみたのですが、同じように書けていると思うのです。
何が問題で動かないかわかりません。

もし、なにか気がついかことがあったら教えてください。

発生している問題・エラー

branch Ade has added successfully
Ade
Exception in thread "main" java.lang.NullPointerException
    at Main.main(Main.java:10)

該当するソースコード Main Class


public class Main {

    public static void main(String[] args) {

        Bank bank = new Bank("National Australia Bank");

        bank.addBranch("Ade");
        bank.showBranches();
        System.out.println(bank.findBranch("Ade").getName());


//      bank.addCustomer("Ade", "Tim", 50.05);


//      bank.listCustomers("Ade", true);

        //      bank.addCustomer("Ade", "Mike", 175.34);
        //      bank.addCustomer("Ade", "Percy", 220.12);
        //
        //      bank.addCustomerTransaction("Ade","Tim", 42.22);
        //      bank.addCustomerTransaction("Ade","Tim", 12.44);
        //      bank.addCustomerTransaction("Ade","Tim", 1.65);
        //
        //      bank.listCustomers("Ade", true);
        //
        //      bank.addBranch("Sydney");
        //      bank.addCustomer("Sydney", "Tim", 50.05);
        //
        //

    }

}

該当するソースコード Bank Class

import java.util.ArrayList;

public class Bank {


    private String name;
    private ArrayList<Branch> branches;


    public Bank(String name) {
        this.name = name;
        this.branches= new ArrayList<Branch>();
    }


    public String getName() {
        return name;
    }


    public void setName(String name) {
        this.name = name;
    }


    public ArrayList<Branch> getBranches() {
        return branches;
    }


    public void setBranches(ArrayList<Branch> branches) {
        this.branches = branches;
    }

    public void addBranch(String name) {
        if(findBranch(name)==null) {
            Branch branch = Branch.creatNewBranch(name);
            branches.add(branch);
            System.out.println("branch " + name + " has added successfully");
        }
    }

    public Branch findBranch(String bname) {

        for(int i =0 ; i>branches.size(); i++ ) {
            if(branches.get(i).getName().equals(bname)) {
                return branches.get(i);
            }
        } return null;
    }

    public boolean listCustomers(String bName ,boolean pTransaction ) {
        if(findBranch(bName)!=null) {
            System.out.println("Customer list for branch : " + bName);
            for(int i =0 ; i < findBranch(bName).getCustomers().size()  ; i++) {
                System.out.println(findBranch(bName).getCustomers().get(i).getName() + "[" + (i+1) + "]");
                if(pTransaction) {
                    findBranch(bName).getCustomers().get(i).showTransactions();
                }
            }
            return true;
        }
        return false;
    }

    public boolean addCustomer(String nBranch, String nCustomer, double iTransaction) {

        if(findBranch(nBranch)!= null) {
            return  findBranch(nBranch).newCustomer(nCustomer, iTransaction);
        } else {
            System.out.println("The branch could not found on the list");
            return false;
        }
    }

    public boolean addCustomerTransaction(String nBranch, String nCustomer, double transaction) {
        if(findBranch(nBranch).addCustomerTransaction(nCustomer, transaction)) {
            System.out.println("The customer was added successfully");
            return true;
        }
        System.out.println("The transaction was not added");
        return false;
    }

    public void showBranches() {
        for(int i=0 ; i <branches.size(); i++ ) {
            System.out.println(branches.get(i).getName());
        }
    }


}

該当するソースコード Branch Class

import java.util.ArrayList;

public class Branch {

    private static final String String = null;
    private String name;
    private ArrayList<Customer> customers;


    public Branch(String name) {
        this.name = name;
        this.customers = new ArrayList<Customer>();
    }


    public String getName() {
        return name;
    }


    public void setName(String name) {
        this.name = name;
    }


    public ArrayList<Customer> getCustomers() {
        return customers;
    }


    public void setCustomers(ArrayList<Customer> customers) {
        this.customers = customers;
    }

    public boolean newCustomer(String name, double transaction ) {
        Customer newCustomer = findCustomer(name);
        if (newCustomer==null) {
            customers.add(Customer.creatCustomer(name, transaction));
            System.out.println("new customer has added successfully");
            return true;
        }else {
            System.out.println("this customer exisits");
            return false;
        }
    }

    private Customer findCustomer(String name) {
        for(int i=0 ; i < customers.size() ; i++) {
            if(name.equals(customers.get(i).getName())) {
                return customers.get(i);
            }
        }  return null;
    }

    public boolean addCustomerTransaction(String name,double transaction) {
        if(findCustomer(name)!=null) {
            findCustomer(name).getTransactions().add(transaction);
            System.out.println("Transaction was added successfully");
            return true;
        }
        return false;
    }

    public static Branch creatNewBranch(String name) {
        Branch branch = new Branch(name);
        return branch;
    }





}

該当するソースコード Customer Class

import java.util.ArrayList;

public class Customer {

    private String name;
    private ArrayList<Double> transactions;


    public Customer(String name, double transaction) {
        this.name = name;
        this.transactions =new ArrayList<Double>();
        transactions.add(transaction);
    }

    public String getName() {
        return name;
    }


    public void setName(String name) {
        this.name = name;
    }


    public ArrayList<Double> getTransactions() {
        return transactions;
    }


    public void setTransactions(ArrayList<Double> transactions) {
        this.transactions = transactions;
    }

    public void addTransaction(double transaction) {
        transactions.add(transaction);
    }

    public static Customer creatCustomer(String name, double transaction) {
        Customer customer = new Customer(name, transaction);
        return customer;
    }

    public void showTransactions() {
        for(int i=0 ; i < transactions.size(); i++) {
            System.out.println("Customer name"+ name);
            System.out.println("transaction"+ transactions.get(i));
        }
    }

}

該当するソースコード 模範回答　Bank Class

package com.timbuchalka;
import java.util.ArrayList;

/**
 * Created by dev on 4/09/15.
 */
public class Bank {
    private String name;
    private ArrayList<Branch> branches;

    public Bank(String name) {
        this.name = name;
        this.branches = new ArrayList<Branch>();
    }

    public boolean addBranch(String branchName) {
        if(findBranch(branchName) == null) {
            this.branches.add(new Branch(branchName));
            return true;
        }

        return false;
    }

    public boolean addCustomer(String branchName, String customerName, double initialAmount) {
        Branch branch = findBranch(branchName);
        if(branch != null) {
            return branch.newCustomer(customerName, initialAmount);
        }

        return false;
    }

    public boolean addCustomerTransaction(String branchName, String customerName, double amount) {
        Branch branch = findBranch(branchName);
        if(branch != null) {
            return branch.addCustomerTransaction(customerName, amount);
        }

        return false;
    }

    private Branch findBranch(String branchName) {
        for(int i=0; i<this.branches.size(); i++) {
            Branch checkedBranch = this.branches.get(i);
            if(checkedBranch.getName().equals(branchName)) {
                return checkedBranch;
            }
        }

        return null;
    }

   public boolean listCustomers(String branchName, boolean showTransactions) {
       Branch branch = findBranch(branchName);
       if(branch != null) {
           System.out.println("Customer details for branch " + branch.getName());

           ArrayList<Customer> branchCustomers = branch.getCustomers();
           for(int i=0; i<branchCustomers.size(); i++) {
               Customer branchCustomer = branchCustomers.get(i);
               System.out.println("Customer: " + branchCustomer.getName() + "[" + (i+1) + "]");
               if(showTransactions) {
                   System.out.println("Transactions");
                   ArrayList<Double> transactions = branchCustomer.getTransactions();
                   for(int j=0; j<transactions.size(); j++) {
                       System.out.println("[" + (j+1) + "]  Amount "  + transactions.get(j));
                   }
               }
           }
           return true;
       } else {
           return false;
       }
   }
}

該当するソースコード 模範回答　Branch Class

package com.timbuchalka;

import java.util.ArrayList;

/**
 * Created by dev on 4/09/15.
 */
public class Branch {
    private String name;
    private ArrayList<Customer> customers;

    public Branch(String name) {
        this.name = name;
        this.customers = new ArrayList<Customer>();
    }

    public String getName() {
        return name;
    }

    public ArrayList<Customer> getCustomers() {
        return customers;
    }

    public boolean newCustomer(String customerName, double initialAmount) {
        if(findCustomer(customerName) == null) {
            this.customers.add(new Customer(customerName, initialAmount));
            return true;
        }

        return false;
    }

    public boolean addCustomerTransaction(String customerName, double amount) {
        Customer existingCustomer = findCustomer(customerName);
        if(existingCustomer != null) {
            existingCustomer.addTransaction(amount);
            return true;
        }

        return false;
    }

    private Customer findCustomer(String customerName) {
        for(int i=0; i<this.customers.size(); i++) {
            Customer checkedCustomer = this.customers.get(i);
            if(checkedCustomer.getName().equals(customerName)) {
                return checkedCustomer;
            }
        }

        return null;
    }
}

該当するソースコード 模範回答　Customer Class

package com.timbuchalka;

import java.util.ArrayList;

/**
 * Created by dev on 4/09/15.
 */
public class Customer {
    private String name;
    private ArrayList<Double> transactions;

    public Customer(String name, double initialAmount) {
        this.name = name;
        this.transactions = new ArrayList<Double>();
        addTransaction(initialAmount);
    }

    public void addTransaction(double amount) {
        this.transactions.add(amount);
    }

    public String getName() {
        return name;
    }

    public ArrayList<Double> getTransactions() {
        return transactions;
    }
}

自分で試したこと

ここに問題・エラーに対して試したことを記載してください。
コードがうまくうごかないので、基礎になるメソッド　findBranch()が動くか確認してみました。
ここから、もううまく動きませんが、理由がわかりません。
模範回答もあるので、参照しましたが、ようくわからないのでもしわかる方がいたら教えてください。

0

2Answer

vnet
@vnet
    public Branch findBranch(String bname) {

        for(int i =0 ; i>branches.size(); i++ ) {
            if(branches.get(i).getName().equals(bname)) {
                return branches.get(i);
            }
        } return null;
    }

Bank class このメソッド for 回ってますか？

1Like

Comments

  1. @Choco_Late

    Questioner

    たぶん、回ってないんですけど、お手本と見比べて同じだと思うんですよね。

    ```
    private Branch findBranch(String branchName) {
    for(int i=0; i<this.branches.size(); i++) {
    Branch checkedBranch = this.branches.get(i);
    if(checkedBranch.getName().equals(branchName)) {
    return checkedBranch;
    }
    }

    return null;
    }
    ```
tetr4lab
@tetr4lab

BankクラスのfindBranch(String bname)の以下の行で不等号の向きが逆です。

誤
        for(int i =0 ; i>branches.size(); i++ ) {
正
        for(int i =0 ; i<branches.size(); i++ ) {
1Like

Comments

  1. @Choco_Late

    Questioner

    わー、、、、今日1日悩んで分からなかった。
    そうか。。。そうですね。
    思い込みが強くて、何度見えても分からなかったです。
    ありがとうございました。

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