作业一学期二书十四章

1.根据目录结构myjava/practice1/Foo.java,写出Foo类的包名。
包名为：myjava.practice1:
2.改写第12章中简答题第3题中的计算机类（Calculator）。要求将加减乘除的方法改写成带参方法，在定义一个运算方法 ope(),接收用户的运算和两个数字，根据用户选择的运算计算结果。

public class DJ14word2Calculator {
    public double add(double num1,double num2){
        System.out.print(num1+"+"+num2+"=");
        return(num1+num2);
    }
    public double minus(double num1,double num2){
        System.out.print(num1+"-"+num2+"=");
        return(num1-num2);
    }
    public double multiple(double num1,double num2){
        System.out.print(num1+"*"+num2+"=");
        return(num1*num2);
    }
    public double divide(double num1,double num2){
        System.out.print(num1+"/"+num2+"=");
        return(num1/num2);
    }
    public double ope(int op,double num1,double num2){
        if(op==1){
            return add(num1,num2);
        }else if(op==2){
            return minus(num1,num2);
        }else if(op==3){
            return multiple(num1,num2);
        }else{
            return divide(num1,num2);
        }
    }
}

import java.util.Scanner;
public class DJ14word2 {
    @SuppressWarnings({ "resource" })
    public static void main(String[] args) {
        DJ14word2Calculator calc=new DJ14word2Calculator();
        Scanner i=new Scanner(System.in);
        System.out.print("请选择运算:1.加法2.减法3.乘法4.除法:");
        int op=i.nextInt();
        System.out.print("请输入第一个数:");
        double num1=i.nextDouble();
        System.out.print("请输入第二个数:");
        double num2=i.nextDouble();
        System.out.println(calc.ope(op,num1,num2));
    }
}

3.模拟一个简单的购房商贷月供计算器，假设按照以下的公式计算出总利息和每月还款金额。

public class DJ14word3Loan {
    public double loan(double loan,int yearchoice){
        double money=0;
        switch(yearchoice){
        case 1:
            money=loan*1.0603/36;
            System.out.println("月供为:"+money);
            break;
        case 2:
            money=loan*1.0612/60;
            System.out.println("月供为:"+money);
            break;
        case 3:
            money=loan*1.0639/240;
            System.out.println("月供为:"+money);
            break;
        default:
            System.out.println("请输入正确的数字!");
            break;
        }
        return money;
    }
}

import java.util.Scanner;


public class DJ14word3 {
    @SuppressWarnings({ "unused", "resource" })
    public static void main(String[] args) {
        DJ14word3Loan l=new DJ14word3Loan();
        Scanner i=new Scanner(System.in);
        System.out.print("请输入贷款金额:");
        double lloan=i.nextDouble();
        System.out.print("请输入贷款年限:1.3年(36个月)2.5年(60个月)3.20年(240个月)");
        int lyearchoice=i.nextInt();
    }
}

4.根据指定不同的行及字符，生成不同的三角形。

public class DJ14word4Triangle {
    public void printTriangle(int row,String ch){
        for(int a=0;a<row;a++){
            for(int b=0;b<=a;b++){
            System.out.print(ch);   
            }
            System.out.println();
        }
    }
}

import java.util.Scanner;


public class DJ14word4 {
    @SuppressWarnings("resource")
    public static void main(String[] args) {
        DJ14word4Triangle l=new DJ14word4Triangle();
        Scanner i=new Scanner(System.in);
        System.out.print("请输入行数:");
        int lrow=i.nextInt();
        System.out.print("请输入打印的字符:");
        String lch=i.next();
        l.printTriangle(lrow,lch);
    }
}

5.根据三角形的三条边长，判断其是直角、钝角，还是锐角三角形。


public class DJ14word5Triangle {
    public boolean it(int a,int b,int c){
        boolean flag=false;
        if((a+b)>c&&(a+c)>b&&(c+b)>a){
            flag=true;
        }
        return flag;
    }
    public String shape(int a,int b,int c){
        String shape="";
            if(a==b&&b==c){
                shape="这是个等边三角形";
            }else if(a==b||b==c||c==a){
                shape="这是个等腰三角形";
            }else if(a*a+b*b==c*c||a*a+c*c==b*b||b*b+c*c==a*a){
                shape="这是个直角三角形";
            }else if(a*a+b*b>c*c||a*a+c*c>b*b||b*b+c*c>a*a){
                shape="这是个锐角三角形";
            }else if(a*a+b*b<c*c||a*a+c*c<b*b||b*b+c*c<a*a){
                shape="这是个钝角三角形";
            }
            return shape;
    }
}
import java.util.Scanner;


public class DJ14word5 {
    @SuppressWarnings("resource")
    public static void main(String[] args) {
        DJ14word5Triangle l=new DJ14word5Triangle();
        String answer="";
        Scanner i=new Scanner(System.in);
        do{
                System.out.print("请输入第1条边:");
                int a=i.nextInt();
                System.out.print("请输入第2条边:");
                int b=i.nextInt();
                System.out.print("请输入第3条边:");
                int c=i.nextInt();
                if(l.it(a,b,c)){
                    System.out.println(l.shape(a,b,c));
                }else{
                    System.out.println("这不能构成三角形");
                }
                System.out.print("继续吗?(y/n):");
                answer=i.next();
        }while("y".equals(answer));
        System.out.println("谢谢使用!");
    }
}

6.编写程序，向整型数组的指定位置插入元素，并输出插入前后数组的值。


public class DJ14word6ia {
    public void insertArray(int[] arr,int index,int value){
        for(int a=arr.length-1;a>=index;a--){
            arr[a]=arr[a-1];   //向后移一位
        }
        arr[index-1]=value;    //赋值
    }
}

public class DJ14word6 {
    public static void main(String[] args) {
        int[] a=new int[20];   //定义一个新数组
        a[0]=45;
        a[1]=12;
        a[2]=0;
        a[3]=87;
        a[4]=21;
        a[5]=1;
        a[6]=89;
        a[7]=123;
        a[8]=21;
        System.out.println("插入前:");
        for(int i=0;i<a.length-1;i++){
            System.out.print(a[i]+"  ");
        }
        DJ14word6ia ia=new DJ14word6ia();   //引用另一页
        ia.insertArray(a,3,10);             //赋值
        System.out.println("\n插入后:");
        for(int i=0;i<a.length-1;i++){
            System.out.print(a[i]+"  ");
        }
    }
}

7.本学期期末学员共参加了三门课，即Java、C、SQL,编写方法计算每位学员三门课的平均分。




public class DJ14word7student {
    public int java;
    public int C;
    public int SQL;
}

public class DJ14word7studentBiz {
    public double getAvg(DJ14word7student stu){
        return (stu.java+stu.C+stu.SQL)/3;
    }
}
import java.util.Scanner;


public class DJ14word7 {
    @SuppressWarnings("resource")
    public static void main(String[] args) {
        DJ14word7student curriculum=new DJ14word7student();
        Scanner i=new Scanner(System.in);
        System.out.print("请输入你的java成绩:");
        curriculum.java=i.nextInt();
        System.out.print("请输入你的C成绩:");
        curriculum.C=i.nextInt();
        System.out.print("请输入你的SQL成绩:");
        curriculum.SQL=i.nextInt();

        DJ14word7studentBiz calculation=new DJ14word7studentBiz();
        double avg=calculation.getAvg(curriculum);
        System.out.println("你的平均分是:"+avg);
    }
}

作业一学期二书十四章

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