1000 trucos de programación para Java

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http://javaa.com/

Hacer casting en el tipo de dato en Java

Hacer casting o conversiones en el tipo de dato en Java

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( 0×10000 i).substring(1).toUpperCase());
}
}
hexadecimal 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;