老韩Java第七章作业汇总(自做)

快来打我* 2024-03-30 13:45 19阅读 0赞

韩老师(韩顺平)java第七章所有习题自己写的而且可以运行都放在这里了。

### 问题1：编写类A01,定义方法max，实现求某个double数组的最大值，并返回Homework01.java ###

public class HomeWork01 {
        
        public static void main(String args[]){
        
            double[] a = {
        1.1,2.2,3.3,4.4,5.5};
            //主函数
            A01 b = new A01();
            b.max(a);
        }
        //方法函数,最值获取
    }
    class A01{
        
        public  void max(double a[]){
        
            double mx = a[0];
            for(int i = 1;i<a.length;i++){
        
                if(a[i] > mx){
        
                    mx = a[i];
                }
            }
            System.out.println(mx);
        }
    }

### 问题2 编写类A02 ,定义方法find，实现查找某字符数组中的元素查找，并返回索引，如果找不到返回-1 ###

public class HomeWork01 {
        
        public static void main(String args[]){
        
            String[] a = {
        "aa","bb","cc","dd","ee"};
            String st = "aa";
            A02 b = new A02();
            System.out.println("找到的字符串下标位:" + b.find(a,st));
            //主函数
        }
    }
    class A02{
        
        //-1其实是一个哨兵岗
        public int find(String a[],String st){
        
            int idx = -1;
            for(int i=0;i<a.length;i++){
        
                if(st.equals(a[i])){
        
                    idx =i;
                    break;
                }
            }
            return idx;
        }
    
    }

![在这里插入图片描述][6d04a8d1a46a4f64a001ad0c5ed5cdbc.png]

### 问题3 编写类Book,定义方法updatePrice，实现更改本书的价格，具体，如果价格>150,则更改为150，如果>100,更改为100，否则不变 ###

public class HomeWork01 {
        
        public static void main(String args[]){
        
            Book b = new Book(159.2);
            b.updatePrice();
            System.out.println(b.price);
    
        }
        //方法函数,最值获取
    }
    class Book{
        
        double price;
        public Book(double v) {
        
            price = v;
        }
        public void updatePrice(){
        
            if(this.price > 150.0)
                this.price = 150.0;
            else if(this.price > 100)
                this.price = 100.0;
        }
    }

![在这里插入图片描述][bb23c8452db94538a0de706a4f57e8f7.png]

### 问题4 编写类A03,实现数组的复制功能copyArr,输入旧数组，返回一个新数组，元素和旧数组一样 ###

public class HomeWork01 {
        
        public static void main(String args[]){
        
            int[] a = {
        1,2,3,4,5};
            A03 tmp = new A03();//临时对象
            int[] b = tmp.CopyArray(a);
            for (int ele:b 
                 ) {
        //打印输出
                System.out.println(ele);
            }
        }
    }
    class A03{
        
        public int[] CopyArray(int a[]){
        
            int[] b = new int[a.length];
            for(int i=0;i<a.length;i++)
                b[i] = a[i];
            return b;
        }
    
    
    }

![在这里插入图片描述][3eecb4727c6744ab8988f022e5a9f7e1.png]

### 问题5 定义一个圆类Circle，定义属性：半径，提供显示圆周长功能的方法，提供显示圆面积的方法 ###

public class HomeWork01 {
        
        public static void main(String args[]){
        
            Circle c = new Circle(3.0);
            c.printArea();
            c.printPerimeter();
        }
    }
    class Circle{
        
        double r;
        public Circle(double r) {
        
            this.r = r;
        }
        public void printPerimeter(){
        
            System.out.println("圆的周长" + 2*3.1415*this.r);
        }
        public void printArea(){
        
            System.out.println("圆的面积" + this.r*3.1415*this.r);
    
        }
    }

![在这里插入图片描述][410e240265a94c31aedeef19be6a4f8d.png]

### 问题6 编程创建一个Cale计算类，其中定义2个变量表示两个操作数，定义四个方法实现求和差乘商，除数为0给提示，并创建两个对象。 ###

public class HomeWork01 {
        
        public static void main(String args[]){
        
            Cale c = new Cale(1.1,0.0);
            c.div();
            Cale d = new Cale(1.1,2.2);
            d.add();
            d.mul();
            d.reduce();
        }
    
        //
    
    }
    class Cale{
        
        double sum1;
        double sum2;
    
        public Cale(double v, double v1) {
        
            sum1 = v;
            sum2 = v1;
        }
    
        public void add(){
        
            System.out.println("两数之和 " + (this.sum1+this.sum2));
        }
        public void reduce(){
        
            System.out.println("两数之差 " + (this.sum1-this.sum2));
        }
        public void mul(){
        
            System.out.println("两数之积 " + (this.sum1*this.sum2));
    
        }
        public void div(){
        
            if((this.sum2-0.0)<1e-4){
        
                System.out.println("除数为0");
            }else{
        
                System.out.println("两数之商" + (this.sum1/this.sum2));
            }
        }
    }

![在这里插入图片描述][ce716186f1c047cc9bcd2c2587dd0b74.png]

### 问题7：设计一个Dog类，有名字颜色年龄，定义输出方法show（）显示信息，并创建对象进行测试 ###

public class HomeWork01 {
        
        public static void main(String args[]){
        
            Dog dg = new Dog("旺财","红色",2);
            dg.printInfo();
        }
    
        //
    
    }
    class Dog{
        
        String name;
        String color;
        int age;
    
        public Dog(String s, String s1, int i) {
        
            this.name = s;
            this.color = s1;
            this.age = i;
        }
        void printInfo(){
        
            System.out.println("狗的名字叫" + this.name + ",颜色为:" + this.color + ",狗的年龄为:" + this.age );
        }
    }

![在这里插入图片描述][3b4bad96bb38448caca79a83fd54c0e6.png]

### 问题8:给定一个java程序代码如下所示，则编译运行后，输出结果是() ###

public class Test {
        
        int count = 9;
        public void count1(){
        
            count = 10;
            System.out.println("count1 = " + count);
        }
        public void count2(){
        
            System.out.println("count2 = " + count++);
        }
        public static void main(String args[]){
        
            new Test().count1();
            Test t1 = new Test();
            t1.count2();
            t1.count2();
        }
    }

![在这里插入图片描述][124e2470a1fc419ab1f0cedffa5fb3d4.png]

### 问题9 定义music类，里面有音乐名name,音乐时长times属性，并有播放play功能和返回本身属性信息的功能方法getInfo ###

public class Music {
        
        public static void main(String[] args){
        
    
            Mus mu = new Mus("青花瓷",242);
            mu.Play();
            mu.getInfo();
        }
    }
    
    class Mus{
        
        String name;
        int time;
    
        public Mus(String name, int i) {
        
            this.name = name;
            this.time = i;
        }
    
        void Play(){
        
            System.out.println("音乐播放中....");
        }
        void getInfo(){
        
            System.out.println("歌曲名称:" + this.name + ",歌曲时长" + this.time/60 + "分" + this.time%60 + "秒");
        }
    }

![在这里插入图片描述][c577bbd929f646d3a386fb138984cf90.png]

### 问题10 试写出以下代码运行结果() ###

public class Demo{
        
        public static void main(String args[]){
        
            Dem d1 = new Dem();
            Dem d2 = d1;
            d2.m();
            System.out.println(d1.i);
            System.out.println(d1.i);
        }
    }
     class Dem {
        
        int i = 100;
        public void m(){
        
            int j = i++;
            System.out.println("i="+i);
            System.out.println("j="+j);
        }
    
    }

![在这里插入图片描述][b81402ea26c9443ba54dc6f4c823fdb5.png]

### 问题11 在测试方法中，调用method方法，代码如下，编译正确，调用语句System.out.println(method(method(10.0,20.0),100)); ###

public class HomeWork11 {
        
        public double method(double a,double b){
        
            return a+b;
        }
        static int method(double a, int b){
        
            return (int) (a + (double)b);
        }
        public static void main(String args[]) {
        
            System.out.println(method(method(10.0, (int) 20.0), 100));
        }
    }

![在这里插入图片描述][9e544d344ec2479b8560650813fd3342.png]

### 问题12 创建一个Employee类，属性有(名字，性别，年龄，职位，薪水)，提供三个构造方法，1.(名字，性别，年龄，职位，薪水),2,(名字，性别，年龄),(3)(职位，薪水) ###

public class HomeWork12 {
        
        public static void main(String args[]){
        
            Employee e1 = new Employee("高级工程师",15500);
            Employee e2 = new Employee("张怀",'男',22);
            Employee e3 = new Employee("李华",'男',23,"中级工程师",15500);
            System.out.println(e3.age);
            System.out.println(e3.name);
            System.out.println(e3.gender);
            System.out.println(e3.position);
            System.out.println(e3.salary);
        }
    }
    class Employee{
        
        String name;
        char gender;
        int age;
        String position;
        int salary;
    
        public Employee(String position, int salary) {
        
            this.position = position;
            this.salary  = salary;
        }
    
        public Employee(String name, char gender, int age) {
        
            this.name = name;
            this.gender = gender;
            this.age  = age;
    
        }
    
        public Employee(String name, char gender, int age, String position, int salary) {
        
    
            this(name,gender,age);
            this.position = position;
            this.salary = salary;
    
            System.out.println("构造函数.....");
    
    
        }
    
    }

![在这里插入图片描述][641083bdd1734ce698fc7c9788e86004.png]

### 问题13 ###

![在这里插入图片描述][119c0282499646248ea20bc01dc42e6e.png]

import javax.swing.plaf.basic.BasicIconFactory;
    
    public class HomeWork13 {
        
        public static void main(String args[]){
        
            PassObject ps = new PassObject();
            Circle c = new Circle();
            ps.printAreas(c,5);
    
        }
    }
    class Circle{
        
        double r;
        double findArea(){
        
            return 3.14159*r*r;
        }
    }
    class PassObject{
        
        public void printAreas(Circle c,int times){
        
            System.out.println("Radius\t\tArea");
            for(int i =1;i<=times;i++){
        
                c.r = (double) i;
                System.out.println(c.r + "\t\t" + c.findArea());
            }
        }
    }

![在这里插入图片描述][ecd565b370cf4ae28d7e7061d6e4baf4.png]

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[124e2470a1fc419ab1f0cedffa5fb3d4.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/30/3a46cf0003dd4d4e9359c143d5e08d4d.png
[c577bbd929f646d3a386fb138984cf90.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/30/c75f77e1f9c742a2bdf31fea208ae4f0.png
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