JAVA数据类型转换

• 将字串 String 转换成数字类型

String 转 int

 int i = Integer.parseInt([String]); 或 i = Integer.parseInt([String],[int radix]); 
 int i = Integer.valueOf(my_str).intValue(); 

String 转 Float

Float f = Integer.valueOf(my_str).floatValue();

String 转 float

float f=new Float(my+str).floatValue();

注: 字串转成 Double, Float, Long 的方法大同小异.

• 将整数 int 转换成字串 String

String s = String.valueOf(i); 
String s = Integer.toString(i); 
String s = "" + i; 

注: Double, Float, Long 转成字串的方法大同小异.

 

JAVA中常用数据类型转换函数
虽然都能在JAVA API中找到，整理一下做个备份。

 

string->byte
Byte static byte parseByte(String s)  
 
byte->string 
Byte static String toString(byte b) 
 
char->string 
Character static String to String (char c) 
 
string->Short 
Short static Short parseShort(String s) 
 
Short->String 
Short static String toString(Short s) 
 
String->Integer 
Integer static int parseInt(String s)
 
Integer->String 
Integer static String tostring(int i) 
 
String->Long 
Long static long parseLong(String s) 
 
Long->String 
Long static String toString(Long i) 
 
String->Float 
Float static float parseFloat(String s) 
 
Float->String 
Float static String toString(float f) 
 
String->Double 
Double static double parseDouble(String s)
 
Double->String
Double static String toString(Double d)

 这是一个例子,说的是JAVA中数据数型的转换.供大家学习引

package cn.com.hdu;
import java.sql.Date;
public class TypeChange {
  public TypeChange() {
  }
  //change the string type to the int type
  public static  int stringToInt(String intstr)  {
    Integer integer;
    integer = Integer.valueOf(intstr);
    return integer.intValue();
  }
  //change int type to the string type
  public static String intToString(int value)  {
    Integer integer = new Integer(value);
    return integer.toString();
  }
  //change the string type to the float type
  public static  float stringToFloat(String floatstr)  {
    Float floatee;
    floatee = Float.valueOf(floatstr);
    return floatee.floatValue();
  }
  //change the float type to the string type
  public static String floatToString(float value)  {
    Float floatee = new Float(value);
    return floatee.toString();
  }
  //change the string type to the sqlDate type
  public static java.sql.Date stringToDate(String dateStr)  {
    return  java.sql.Date.valueOf(dateStr);
  }
  //change the sqlDate type to the string type
  public static String dateToString(java.sql.Date datee)  {
    return datee.toString();
  }
 
  public static void main(String[] args)  {
    java.sql.Date day ;
    day = TypeChange.stringToDate("2003-11-3");
    String strday = TypeChange.dateToString(day);
    System.out.println(strday);
  }
 

}