Question

所以我现在正在制作代码，搜索arraylists并打印出最大的代码。此代码提示用户输入BankAccount名称以及帐户有多少钱。目前我遇到的问题是不知道如何通过arraylists搜索最大数字。我也不知道如何将每个余额与maxBalance进行比较。感谢任何帮助，谢谢。

        import java.io.*;
        import java.util.*;
        import java.text.*; 

        public class Project43Tester
        {
            public static void main(String args[])
            {
                NumberFormat formatter = NumberFormat.getNumberInstance( );
                formatter.setMinimumFractionDigits(2);
                formatter.setMaximumFractionDigits(2);
                String name;
                ArrayList <String> aryLst = new ArrayList<String>();

                do
                {
                    Scanner kbReader = new Scanner(System.in);
                    System.out.print("Please enter the name to whom the account belongs.(\"Exit\" to abort)");
                    name = kbReader.nextLine( );
                    if( !name.equalsIgnoreCase("EXIT") )
                    {
                        System.out.print("Please enter the amount of the deposit. ");
                        double amount = kbReader.nextDouble();
                        System.out.println(" ");
                        ArrayList <String> BankAccount = new <String> ArrayList();
                        AryLst.add(BankAccount);
                    }
                }while(!name.equalsIgnoreCase("EXIT"));

        Search aryList and print out the name and amount of the largest bank account

                BankAccount ba = //get first account in the list
                    double maxBalance = ba.balance;
                String maxName = ba.name;

                for(int j = 1; j < aryLst.size( ); j++)
                {
                    ?
                    ? Step through the remaining objects and decide which one has
                    largest balance (compare each balance to maxBalance)
                    ?
                }

                System.out.println(" ");
                System.out.println("The account with the largest balance belongs to " + maxName + ".");
                System.out.println("The amount that the account contains is $" + formatter.format(maxBalance) + ".");
            }
        }

Answer 1

您必须遍历ArrayList。在遍历ArrayList期间，将第一个元素设置为max并将其与next进行比较。如果它更大，则将新元素设置为最大值

Answer 2

最简单的方法是使用ArrayList's sort function.没有头痛。请参阅此link

Answer 3

List<String> l = new ArrayList<String>();
l.add("2.33");
l.add("3.45");
l.add("1.11");

Collections.sort(l);
for(String s: l) {
    System.out.println(s);
}

结果：

1.11
2.33
3.45

Answer 4

这是您的代码的略微修改版本。建议使用Comparable / Comparator进行排序（您应该尝试;修改下面的代码）。

这是通过数组迭代和访问示例的对象属性的简单遍历。

import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;


public class Project43Tester
{
    static class BankAccount
    {
        String name;
        Double amount;

        public BankAccount(String name, Double amount)
        {
            this.name = name;
            this.amount = amount;
        }

        public String getName()
        {
            return name;
        }

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

        public Double getAmount()
        {
            return amount;
        }

        public void setAmount(Double amount)
        {
            this.amount = amount;
        }

    }

    public static void main(String args[])
    {
        NumberFormat formatter = NumberFormat.getNumberInstance();
        formatter.setMinimumFractionDigits(2);
        formatter.setMaximumFractionDigits(2);
        String name = null;
        List<BankAccount> bankAccounts = new ArrayList<BankAccount>();

        do
        {
            Scanner kbReader = new Scanner(System.in);
            System.out.print("Please enter the name to whom the account belongs.(\"Exit\" to abort)");
            name = kbReader.nextLine();
            if (!"EXIT".equalsIgnoreCase(name))
            {
                System.out.print("Please enter the amount of the deposit. ");
                double amount = kbReader.nextDouble();
                System.out.println(" ");

                bankAccounts.add(new BankAccount(name, amount));
            }
        }
        while (!"EXIT".equalsIgnoreCase(name));

        BankAccount maxBankAccount = null;

        for (BankAccount bankAccount : bankAccounts)
        {
            if (maxBankAccount == null)
            {
                maxBankAccount = bankAccount;
            }
            else if(bankAccount.getAmount() > maxBankAccount.getAmount())
            {
                maxBankAccount = bankAccount;
            }
        }

        System.out.println(" ");
        System.out.println("The account with the largest balance belongs to " + maxBankAccount.getName() + ".");
        System.out.println("The amount that the account contains is $" + formatter.format(maxBankAccount.getAmount()) + ".");
    }
}

通过arraylists搜索最大数量

4 个答案: