12.19日作业

最新推荐文章于 2024-09-24 16:19:42 发布

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最新推荐文章于 2024-09-24 16:19:42 发布

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本文链接：https://blog.youkuaiyun.com/weixin_38323767/article/details/85108317

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本文深入探讨了Java集合框架的应用，包括HashMap和ArrayList的使用案例。通过具体的代码示例，展示了如何利用Map和List进行数据存储和操作，以及Account类的设计与实现，强调了Java在数据管理和对象操作方面的强大功能。

import java.util.HashMap;
import java.util.Map;

HomeWork15.java

	Map<String, String> m=new HashMap<>();
		m.put("Tom", "CoreJava");
		m.put("John", "Oracle");
		m.put("Susan", "Oracle");
		m.put("Jerry", "JDBC");
		m.put("Jim", "Unix");
		m.put("Kevin", "JSP");
		m.put("Lucy", "JSP");
		
		m.put("Allen", "JDBC");
		
		m.put("lucy", "CoreJava");
		
		for (String s : m.keySet()) {
			System.out.println(s+"="+m.get(s));
		}
		
		System.out.println("-----------------华丽的分割线-----------------");
		
		for (String s : m.keySet()) {
			if(m.get(s)=="JSP"){
				System.out.println(s);			
			}
		}

import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;

Account.java

private long id;
	private double balance;
	private String password;
	//无参
	public Account() {
		super();
	}
	//有参
	public Account( double balance, String password) {
		super();
		Random r=new Random();
		this.id =new Date().getTime()+r.nextInt(10);
		this.balance = balance;
		this.password = password;
	}

	public long getId() {
		return id;
	}
	public void setId(long id) {
		this.id = id;
	}
	public double getBalance() {
		return balance;
	}
	public void setBalance(double balance) {
		this.balance = balance;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}

	@Override
	public String toString() {
		return "Account [id=" + id + ", balance=" + balance + ", password=" + password + "]";
	}
	
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		long temp;
		temp = Double.doubleToLongBits(balance);
		result = prime * result + (int) (temp ^ (temp >>> 32));
		result = prime * result + (int) (id ^ (id >>> 32));
		result = prime * result + ((password == null) ? 0 : password.hashCode());
		return result;
	}
	
	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Account other = (Account) obj;
		if (Double.doubleToLongBits(balance) != Double.doubleToLongBits(other.balance))
			return false;
		if (id != other.id)
			return false;
		if (password == null) {
			if (other.password != null)
				return false;
		} else if (!password.equals(other.password))
			return false;
		return true;
	}
	
	HomeWork16.java
	
		List<Account> list=new ArrayList<>();
		list.add(new Account(10.00,"1234"));
		list.add(new Account(15.00,"5678"));
		list.add(new Account(0,"1010"));
		
		Map<Long, Account> m=new HashMap<>();
		
		m.put(list.get(0).getId(), list.get(0));
		m.put(list.get(1).getId(), list.get(1));
		m.put(list.get(2).getId(), list.get(2));
		
		for (Long a : m.keySet()) {
			System.out.println("Id为:"+a+"\r\n"+"余额为："+m.get(a).getBalance());
		}