老韩Java第七章作业汇总(自做)
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;}}
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;}}
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;}}
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);}}
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));}}}
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 );}}
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();}}
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");}}
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);}}
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));}}
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.....");}}
问题13
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());}}}
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