App Programming/JAVA2009.06.23 21:55



Dealing with nulls

UtilFactory.convertNull

 

Java – comparing strings

Use == for primitive data types like int

If (mystring == null)

 

Use the equals() method to compare objects

Use .equals for strings  : if (a.equals(“cat”))

 

Java - Converting int to string

 

String myString = Integer.toString(my int value)

   or

   String str = "" + i

 

Java - Converting String to int

 

int i = Integer.parseInt(str);

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

 

 

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 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();


decimal to binary :

   int i = 42;

   String binstr = 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);    



ASCII code to String

int i = 64;

   String aChar = new Character((char)i).toString();


integer to ASCII code (byte)

char c = 'A';

   int i = (int) c; // i will have the value 65 decimal



integer to boolean

   b = (i != 0);

 

boolean to integer

i = (b)?1:0;

 



Posted by BAGE