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;