面试题,多谢_J2SE

面试题,谢谢
写一个函数，检查字符串是否为整数，如果是，返回其整数值(Java)，

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修改2#代码
Java code
import java.util.regex.Matcher;import java.util.regex.Pattern;public class TestInteger {    static int check(String s) {        Pattern p = Pattern.compile("[+-]?\\d+");        Matcher m = p.matcher(s);        while (m.matches()) {            return Integer.parseInt(s);        }        return -1;    }    public static void main(String[] args) {        String s = "12315465";        int j = check(s);        System.out.println("j=" + j);        String s1 = "-22";        int k = check(s1);        System.out.println("k=" + k);    }}
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探讨
Java code
import java.util.regex.*;
public class TestInteger {
    static int check(String s){
        Pattern p=Pattern.compile("\\d+");
        Matcher m=p.matcher(s);
        while(m.matches()){
            return Integer.parseInt(s);
        }
        return -1;
    }

    public static void main(String[] args) {
        String s="12315465";
        int j=check(s);
        Sys…

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Java codeimport java.io.*;public class IsInteger{    public static void main(String[] args) throws Exception     {        while(true)        {            System.out.print("请输入整数字符串:");            BufferedReader br=new BufferedReader(new InputStreamReader(System.in));            String s=br.readLine();            StringBuffer sb=new StringBuffer();                        for(int i=0;i<s.length();i++)            {                if((int)s.charAt(i)>57 ||(int)s.charAt(i)<48)                {                    System.out.println("该字符串不是整数，请重新输入");                    break;                }                else                {                    sb.append(s.charAt(i));                }            }                        if(s.length()==sb.length())                        {                              System.out.println(s);                        }        }    }}