如何产生随机数

常用 Math.random() 来获得一个0.1到1.0之间的double 值，不包括1.0

比如随机产生十个减法算式：

public static void main(String[] args) {

for(int i = 0;i<10;i++){
int number1 = (int)(Math.random()*10);
int number2 = (int)(Math.random()*10);

if(number1 < number2){
int t = number1;
number1 = number2;
number2 = t;
}

System.out.println("What is the "+number1+"-"+number2 );

Scanner input = new Scanner(System.in);
int answer = input.nextInt();

if(number1 - number2 ==answer){
System.out.println("True");
}
else{
System.out.println("False");
}

结果为：

What is the 9-8
2
False
What is the 4-1
3
True