String to Integer (atoi)

来源：互联网发布：java api 操作hdfs 编辑：程序博客网时间：2024/04/19 19:22
public class Solution {    public int atoi(String str) {        // Start typing your Java solution below        // DO NOT write main() function        if(str==null){            return 0;        }        char[] re = str.toCharArray();        boolean negavite = false;        boolean isFirstBlank = true;        long value=0;        for(int i=0;i<re.length;i++){            if(isFirstBlank&&re[i]==' '){                continue;            }            if(isFirstBlank&&(re[i]=='+'||re[i]=='-')){                isFirstBlank=false;                if(re[i]=='-'){                    negavite=true;                }            }else{                isFirstBlank=false;                if(re[i]<='9'&&re[i]>='0'){                    value=value*10+(re[i]-'0');                    if(value>2147483647){                        break;                    }                }                else{                    break;                }            }          }          if(negavite){             value=-value;          }          if(value>2147483647){              return 2147483647;          }          if(value<-2147483648){              return -2147483648;          }        return (int) value;    }}