java作业

思考

 

 

 

 

前面是字符串的拼接，后者是数值相加，前面是字符串，后面的也会当成字符串看

 

 

 

结论： 使用double类型的数值进行计算， 其结果是不精确的。

 

 结论：

枚举不属于原始数据类型，它的每个具体值都引用一个特定的对象。相同的值则引用同一个对象。 可以使用“==”和equals()方法直接比对枚举变量的值，换句话说，对于枚举类型的变量，“==”和equals()方法执行的结果是等价的。

 

 

 

 第一

package ceshi;

import java.util.Random;
import java.util.Scanner;
public class one1 {

public static void main(String[] args) {
Random s=new Random();
int number=0;

for(int i=0;i<20;i++)
{
int a=s.nextInt(100)+1;
int b=s.nextInt(100)+1;
int c=s.nextInt(4)+1;
switch(c)
{
case 1:
System.out.print(a+"+"+b+"= ");
break;
case 2:
System.out.print(a+"-"+b+"= ");
break;
case 3:
System.out.print(a+"*"+b+"= ");
break;
case 4:
System.out.print(a+"/"+b+"= ");
break;



}


number++;
if(number%3==0)
{
System.out.println("\n");
}

}

 

}

}

第二

package ceshi;

import java.util.Random;
import java.util.Scanner;

public class dage {
static Random sc = new Random();
static Scanner mc = new Scanner(System.in);
static int a[] = new int[100];
static int b[] = new int[100];

public static void main(String[] args) {
System.out.println("请输入题目数量");
int s = mc.nextInt();
System.out.print("请输入打印数目");
int d = mc.nextInt();
int number = 1;
for (int i = 0; i < s; i++) {

int numbera = sc.nextInt(99) + 1;
int numberb = sc.nextInt(99) + 1;
if (a[numbera] == 1 || b[numberb] == 1) {
i--;
continue;
}
a[numbera] = 1;
b[numberb] = 1;
}
int aa = 0, bb = 0;
for (int i = 0; i < s; i++) {
while (a[aa] == 0) {
aa++;
}
System.out.print(aa);
aa++;
int m = sc.nextInt(4) + 1;
switch (m) {
case 1:
System.out.print("+");
break;
case 2:
System.out.print("-");
break;
case 3:
System.out.print("*");
break;
case 4:
System.out.print("/");
break;

}
while (b[bb] == 0) {
bb++;
}
System.out.print(bb);
bb++;
if (i % d == d - 1) {
System.out.print("=\n");
} else {
System.out.print("=\t");
}
}}}

第三

package jianmin0909;

import java.util.Scanner;

public class Test {
static Scanner sc = new Scanner(System.in);

static int[] num = new int[1000];

public static void main(String[] args) {

System.out.print("请输入数量：");
int n = sc.nextInt();
System.out.print("请输入每行的数量：");
int m = sc.nextInt();
System.out.print("操作数个数");
int nn = sc.nextInt();
System.out.print("是否有乘除（1是，2否）：");
int nnn = sc.nextInt();
System.out.print("是否括号（1是，2否）：");
int mmm = sc.nextInt();
System.out.print("请输入最大的数值范围：");
int ooo = sc.nextInt();

for (int i = 0; i < n; i++) {
int argss = 0;
int kuohao = (int) (1 + Math.random() * 100) % (nn - 1);
if (nnn == 2) {
kuohao = nn * 2;
argss = 5;
}
for (int j = 0; j < nn - 1; j++) {
if (j == kuohao)
System.out.print("(");

int a = (int) (1 + Math.random() * 100) % ooo;
System.out.print(a);
int b = (int) (1 + Math.random() * 100) % 4;
if (nnn == 2)
b = b % 2;
if (j == kuohao + 1) {
System.out.print(")");
argss++;
}
if (b == 0)
System.out.print("+");
else if (b == 1)
System.out.print("-");
else if (b == 2)
System.out.print("*");
else if (b == 3)
System.out.print("/");

}
int a = (int) (1 + Math.random() * 100) % ooo;
System.out.print(a);
if (argss == 0)
System.out.print(")");

System.out.print("=");
if (i % m == m - 1)
System.out.print("\n");
else
System.out.print("\t\t");

}
}

}