java反转字符串边界溢出

Question

反转一个十进制数，正负数边界溢出报错，边界设定了，为什么还是溢出？

class Solution {
    public int reverse(int x) {
      
        String s=new StringBuffer(Math.abs(x)+"").reverse().toString();  
        Integer newValue = Integer.valueOf(s);  
        
        if(x>0){  
            if(newValue>Integer.MAX_VALUE ||newValue<Integer.MIN_VALUE){  
                return 0;  
            }else{  
                return (int) newValue;  
            }  
        }else{  
              
                return (int)(0-newValue);  
              
        }  
    }
}
public class MainClass {
    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String line;
        while ((line = in.readLine()) != null) {
            int x = Integer.parseInt(line);
            
            int ret = new Solution().reverse(-2147483648);
            
            String out = String.valueOf(ret);
            
            System.out.print(out);
        }
    }
}　

错误：
Error:
Line 5: java.lang.NumberFormatException: For input string: "8463847412-"

Answer 1

其实：

Math.abs(-2147483648) == -2147483648

很有意思吧？

Answer 2

楼上说的没错。请查阅Math.abs()方法（参数为 int）的文档注释，片段如下：

Note that if the argument is equal to the value of Integer.MIN_VALUE, the most negative representable int value, the result is that same value, which is negative.

当方法的参数值等于 int 最小值时，结果为原值。