java程序的一个小问题

题目：输入a，输入b,输入操作符如“+”,结果result的值等于a与b在进行输入操作符的运算，如：输入：+，则result为a+b。下面是我自己写的代码
import java.util.*;
public class Calculate{
public static void main(String args[]){
System.out.println("输入操作符");
Scanner caozuofu=new Scanner((System.in));
char op=caozuofu.nextInt();
System.out.println("输入操作数1");
Scanner caozuoshu1=new Scanner((System.in));
float a=caozuoshu1.nextInt();
System.out.println("输入操作数2");
Scanner caozuoshu2=new Scanner((System.in));
float b=caozuoshu2.nextInt();
float result=0;
switch(op){
case '+':
result=a+b;
break;
case '-':
result=a-b;
break;
case '*':
result=a*b;
break;
case '/':
result=a/b;

import java.util.*;
public class Calculate{
public static void main(String args[]){
System.out.println("输入操作符");
Scanner caozuofu=new Scanner((System.in));
String str=caozuofu.next();
char op=str.charAt(0);
System.out.println("输入操作数1");
Scanner caozuoshu1=new Scanner((System.in));
float a=caozuoshu1.nextFloat();
System.out.println("输入操作数2");
Scanner caozuoshu2=new Scanner((System.in));
float b=caozuoshu2.nextFloat();
float result=0;
switch(op){
case '+':
result=a+b;
break;
case '-':
result=a-b;
break;
case '*':
result=a*b;
break;
case '/':
result=a/b;
break;
default: