java数据类型之间的转换

java的基本数据类型：short, int, long, float, double, char,string

对应的包装类型：Short, Integer, Long, Float, Double, Character, String

 

基本数据类型和String之间的转换：toString()

1. int to string:

String s = Integer.toString(int n);

2. short to string

String s = Short.toString(short n);

3. long to string

String s = Long.toString(Long n);

4. float to string

String s = Float.toString(Float f)

5. double to string

String s = Double.toString(Double n);

 

String to 基本数据类型：parsexxx(), valueOf()

1. string to int

int n = Integer.parseInt(String s);

int n = Interget.valueOf(String s);

2. String to short

short n = Short.parseShort(String s);

short n = Short.valueOf(String s);

3. String to long

long n = Long.parseLong(String s);

long n = Long.valueOf(String s);

4. String to float

float n = Float.parseFloar(String s);

float f = Float.valueOf(String s);

5. String to double

double d = Double.parseDouble(String s);

double d = Double.valueOf(String s);

 

char to int:

1. 利用char的Unicode编码规则

char c = '8';

int n = c -48;

2. 用Integer.parseInt()

Character ch = '8';

int n =  Interget.parseInt(c.toString());

 

int to char:

int n = 8;

char c = (char)(n+48);

 

package cn.Sandy.Review;

/**
* Hello world!
*
*/
public class App
{
public static void main( String[] args )
{
/**
* String to short/int/long/float/double
*/
String s = "8";

int i = Integer.parseInt(s); //string to int
long l = Long.parseLong(s); //string to long
short sh = Short.parseShort(s); //string to short
float f = Float.parseFloat(s); //string to float
double d = Double.parseDouble(s); //string to double
System.out.println(i);
System.out.println(l);
System.out.println(sh);
System.out.println(f);
System.out.println(d);

/**
* short/int/long/float/double types to string
*/
short sho = 12345;
String sint = Integer.toString(8); // int to string
String sshort = Short.toString(sho); //short to string
String slong = Long.toString(1234562222); //long to string
String sf = Float.toString(3.0f); // float to string
String sd = Double.toString(20.22d); //double to string

System.out.println(sint);
System.out.println(sshort);
System.out.println(slong);
System.out.println(sf);
System.out.println(sd);

/*
* char to int and int to char
*/
int num = 8;
char ch1 = (char)(num + 48); //利用char的unicode编码
System.out.println(ch1);

Character ch2 = '8';//char是基本的数据类型， Character是包装类型
int mun1 = Integer.parseInt(ch2.toString());
System.out.println(ch2);
}


}