java 各种数据类型的互相转换实例代码

StringBuilder转化为String

String str = "abcdefghijklmnopqrs";
StringBuilder stb = new StringBuilder(str);

整型数组转化为字符串

StringBuilder s = new StringBuilder();
 for(i=1;i<=n;i++) {
  s.append(String.valueOf(a[i]));
 }
 String str = ""+s;

字符串转化为整形数组

String str="123456";
int[] a = new int[str.length()];
for(int i=0;i<str.length();i++) {
  a[i] = str.charAt(i)-'0';
}

字符串转化为字符数组

String str="123456";
char[] c = str.toCharArray() ;
System.out.println(c);

字符数组转化为字符串

char[] c = {'a','s','d','4','5',};
String str = new String(c);
System.out.println(str);

字符数组转化为整型数组

char[] c = { '1', '2', '3', '4', '5', };
int[] a = new int[c.length];
 for (int i = 0; i < 5; i++) {
  a[i] = c[i] - '0';
  System.out.println(a[i]);
}

整型数组转化为字符数组

int[] a = {1,2,3,4,5};
char[] c = new char[a.length];
for (int i = 0; i < 5; i++) {
  c[i] = (char) (a[i]+'0');
  System.out.println(c[i]);
}

整型数转化为字符串

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

字符串转化为整型数

int i = Integer.valueOf(str).intValue();

java类型转换 Integer String Long Float Double Date

1如何将字串 String 转换成整数 int?

A. 有两个方法:

1). int i = Integer.parseInt([String]); 或

i = Integer.parseInt([String],[int radix]);

2). int i = Integer.valueOf(my_str).intValue();

注: 字串转成 Double, Float, Long 的方法大同小异.

2 如何将整数 int 转换成字串 String ?

A. 有叁种方法:

1.) String s = String.valueOf(i);

2.) String s = Integer.toString(i);

3.) String s = "" + i;

注: Double, Float, Long 转成字串的方法大同小异.

package cn.com.lwkj.erts.register;
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);
}
} /* 我们 www.jb51.net */

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)

++++++++++++++++++++++++++++++++++++++++++++++++++++++

数据类型

基本类型有以下四种:

int长度数据类型有:byte(8bits)、short(16bits)、int(32bits)、long(64bits)、

float长度数据类型有:单精度(32bits float)、双精度(64bits double)

boolean类型变量的取值有:ture、false

char数据类型有:unicode字符,16位

对应的类类型:Integer、Float、Boolean、Character、Double、Short、Byte、Long

java 各种数据类型的互相转换实例代码

扫一扫手机访问