将整数字符串转换成整数输出（JAVA实现，不能用自带函数）

/** * @author PLA   * 将整数字符串转换成整数输出 */public static void main(String[] args) {String s = "-1456542";change(s);}public static void change(String s){boolean flag = true;long num = 0;int temp;char[] ch = s.toCharArray();for(int i=0;i<ch.length;i++){if((i==0)&&(ch[i] == '+')){flag = true;}else if((i==0)&&(ch[i] == '-')){flag = false;}else if((ch[i]>='0')&&ch[i]<='9'){temp = ch[i]-'0';num = num*10 + temp;}else{System.out.println("Wrong!!!");return;}}if(flag==false){System.out.println(-num);}else{System.out.println(num);}}