Java中各种数字类型转换成字符串型：
String s = String.valueOf( value); // 其中 value 为任意一种数字类型。
字符串型转换成各种数字类型：
String str = "120";
byte b = Byte.parseByte( str );
short t = Short.parseShort( str );
int i = Integer.parseInt( str );
long l = Long.parseLong( str );
Float f = Float.parseFloat( str );
Double d = Double.parseDouble( str );

数字类型与数字类对象之间的转换：

byte b = 120;
Byte bo = new Byte( b );
b = bo.byteValue();

short t = 120;
Short to = new Short( t );
t = to.shortValue();

int i = 169;
b = bo.byteValue();

short t = 169;
Short to = new Short( t );
t = to.shortValue();

int i = 169;
Integer io = new Integer( i );
i = io.intValue();

long l = 169;
Long lo = new Long( l );
l = lo.longValue();

float f = 169f;
Float fo = new Float( f );
f = fo.floatValue();

double d = 169f;
Double dObj = new Double( d );
d = dObj.doubleValue();