自动生成30道小学四则运算题目

package 运算;

 

 

public class sizeyunsuan {

 

    public static void main(String[] args) {

 

        print30Questions();

    }

   

    private static void print30Questions() {

        //说明：生成30道题函数，把接收到的题目字符串按照指定格式输出。

        for (int i = 0; i < 10; i++) {

            System.out.print( i+1 );

            System.out.print("." + getQuestion() + "    ");

            System.out.print( i+11 );

            System.out.print("." + getQuestion() + "    ");

            System.out.print( i+21 );

            System.out.println("." + getQuestion());

        }

    }

 

    private static String getQuestion() {

        //说明：getQuestion()得到题目函数，随机生成题目，返回题目字符串。

        int t = 0;

        String strz = "";   

       

        int x=1+(int)(Math.random()*100);       

        int y=1+(int)(Math.random()*100);   

        int z=1+(int)(Math.random()*100);

       

        if( z<=25 ) {

            strz = "×";

            x = x % 10;

            y = y % 10;//两个各位数相成

        }

        if( z>25 && z<=50 ) {

            strz = "÷";

            y = ( y % 10 ) + 1;//除数不能为0是不是

        }

        if( z>50 && z<=75) {

            strz = "+";

            if ((x+y) > 100) {       

                x = x / 2;

                y = y / 2;//乘法相加结果不大于100

            }       

        }

        if( z>75 ) {

            strz = "-";

            if( x < y ){

                t = y;

                y = x;

                x = t;//保证减法是大数减去小数

            }

        }           

       

        String strx = String.valueOf( x );

        String stry = String.valueOf( y );

 

        String ques = " " + strx + strz + stry + "=";

       

        if(ques.length()==5)ques = ques + " ";

        if(ques.length()==4)ques = ques + "  ";

        if(ques.length()==3)ques = ques + "   ";//保持格式

       

        return ques;

    }//getQuestion

 

}