bound标红怎么办

import java.util.Random;import java.util.Scanner;public class Sc {
public static void main(String[] args){
Random random=new Random();
String sign="";
int i1=random.nextInt(bound: 10);
int i2=random.nextInt(bound: 10);
int int_sign=random.nextInt(bound:4);
int result=0;
switch (int_sign)
{ case1:result=i1+i2; System.out.println(i1+"+"+i2+"=");
case 2:result=i1-i2; System.out.println(i1+"-"+i2+"=");
case 3:result=i1i2; System.out.println(i1+""+i2+"=");
case 4:result=i1/i2; System.out.println(i1+"/"+i2+"=");
} int answer;
Scanner sc=new Scanner(System.in);
answer= sc.nextInt();
if (answer==result){
System.out.println("right"); }
else { System.out.println("wrong" );
}

}
}

不用加冒号

public static void main(String[] args) {
        Random random = new Random();
        String sign = "";
        int i1 = random.nextInt(10);
        int i2 = random.nextInt(10);
        int int_sign = random.nextInt(4);
        int result = 0;
        switch (int_sign) {
            case 1:
                result = i1 + i2;
                System.out.println(i1 + "+" + i2 + "=");
            case 2:
                result = i1 - i2;
                System.out.println(i1 + "-" + i2 + "=");
            case 3:
                result = i1 * i2;
                System.out.println(i1 + "" + i2 + "=");
            case 4:
                result = i1 / i2;
                System.out.println(i1 + "/" + i2 + "=");
        }
        int answer;
        Scanner sc = new Scanner(System.in);
        answer = sc.nextInt();
        if (answer == result) {
            System.out.println("right");
        } else {
            System.out.println("wrong");
        }
    }