Java Conversion (From X type to Y type)

integer to String :
int i = 20;
String str = Integer.toString(i);
   or
String str = "" + i

double to String :
String str = Double.toString(i);

long to String :
String str = Long.toString(l);

float to String :
String str = Float.toString(f);


String to integer :
   str = "50";
   int i = Integer.parseInt(str);
   or
   int i = Integer.valueOf(str).intValue();

String to double :
Double d = Double.valueOf(str).doubleValue();

String to long :
   long l = Long.valueOf(str).longValue();
   or
   Long l = Long.parseLong(str);

String to float :
Float f = Float.valueOf(str).floatValue();

char to String:
String s = String.valueOf('c');


decimal to binary :
int i = 42;
String bin = Integer.toBinaryString(i);

decimal to hexadecimal :
 int i = 42;
 String hexstr = Integer.toString(i, 16);
  or
 String hexstr = Integer.toHexString(i);
   or
(with leading zeroes and uppercase)
   public class Hex {
     public static void main(String args[]){
       int i = 42;
       System.out.print
         (Integer.toHexString( 0x10000 | i).substring(1).toUpperCase());
     }
   }

hexadecimal (String) to integer :
int i = Integer.valueOf("B8DA3", 16).intValue();
   or
int i = Integer.parseInt("B8DA3", 16);
 
integer to ASCII code (byte):
char c = 'A';
int i  = (int) c; // i =  65 DECIMAL

To extract Ascii codes from a String
String test = "ABCD";
for ( int i = 0; i < test.length(); ++i ) {
   char c = test.charAt( i );
   int j = (int) c;
   System.out.println(j);

}

Note :To catch illegal number conversion, use the try/catch clause
Example to use try catch clause
try{
  i = Integer.parseInt(aString);
}
catch(NumberFormatException e) {
  .........
}