关于Java try-catch异常处理

Question

Why there is an exception throwed out while there is nothing to deal wit in my try block?

When I input some string type content,throws out a "Exception in thread "main"

java.lang.NumberFormatException: For input string: "ss""

import java.io.*;

public class Strinput {
    public static void main(String args[]) {
        String s1 = null, s2 = null, ss, si, sf;
        int i1, i2;
        float f1, f2;
        BufferedReader strin = new BufferedReader(new InputStreamReader(
                System.in));
        // please ignore the printing language
        try {
            System.out.print("输入第一个字符串：");
            s1 = strin.readLine();
            System.out.print("输入第二个字符串：");
            s2 = strin.readLine();
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
        i1 = Integer.parseInt(s1);
        i2 = Integer.parseInt(s2);
        f1 = Float.parseFloat(s1);
        f2 = Float.parseFloat(s2);
        ss = strAdd(s1, s2);
        si = strAdd(i1, i2);
        sf = strAdd(f1, f2);
        System.out.println("输入的二个字符串相加结果为：" + ss);
        System.out.println("输入字符串转换为整数相加结果为：" + si);
        System.out.println("输入字符串转换为浮点数相加结果为：" + sf);
    }

    static String strAdd(String str1, String str2) {
        return str1 + str2;
    }

    static String strAdd(int int1, int int2) {
        return String.valueOf(int1 + int2);
    }

    static String strAdd(float flt1, float flt2) {
        return String.valueOf(flt1 + flt2);
    }
}

Answer 1

The exception is thrown after your try/catch!

It happens because you can't convert the string value "ss" within s1 into a number.

The real answer: focus on reading those exception messages: they exactly tell you where the problem is and what caused it. It is all in front of your eyes. And beyond that: such RuntimeExceptions can show up anywhere in your code, they are not restricted to the places where you put down a try/catch!

Answer 2

i think

BufferedReader strin = new BufferedReader(new InputStreamReader(
            System.in));

in the block try/catch