Archives: Basics

Java – Convert String to Long

[code lang=”java”]public class StringToLong {

public static void main(String args[]) {
String strLong = "2323232";

//Convert String to long using Long.valueOf(),better because
//it can cache frequently used long values
long number = Long.valueOf(strLong);
System.out.println("String to long conversion using valueOf :" + number);

//Convert String to long in Java using java.lang.Long object
strLong ="4444444444444444444";
Long numberObject = new Long(strLong);
number = numberObject; //auto boxing will take care of long to Long conversion
System.out.println("String to long conversion example using Long object: " + number);

//Convert String to long with Long.parseLong method in Java
strLong="999999999999999999";
Long parsedLong = Long.parseLong(strLong) ;
number = parsedLong; //auto-boxing will convert Long object to primitive long
System.out.println("String to long conversion using parseLong() method: " + number);

//Convert String to long using Long.decode() method in Java
strLong = "-1023454";
number = Long.decode(strLong);
System.out.println("String to long conversion using decode() method: " + number);

//String to long in hexadecimal format
strLong = "0xFFFF";
number = Long.decode(strLong);
System.out.println("String to long example in hex format decode() method: " + number);

//String to long in octal format
strLong = "0777";
number = Long.decode(strLong);
System.out.println("String to long example in octal format decode() method: " + number);
}
}[/code]
Output:

String to long conversion using valueOf :2323232
String to long conversion example using Long object: 4444444444444444444
String to long conversion using parseLong() method: 999999999999999999
String to long conversion using decode() method: -1023454
String to long example in hex format decode() method: 65535
String to long example in octal format decode() method: 511


Java – Create Immutable Class Example

[code lang=”java”]// declare class as final
final class Immutable {

// declare all variables as final
private final int val1;
private final String val2;

// provide constructor to set the values
public Immutable(int a, String s) {
val1 = a;
val2 = s;
}

// provide getters only
public int getVal1() {
return val1;
}

public String getVal2() {
return val2;
}
}[/code]
[code lang=”java”]public class ImmutableClassDemo {
public static void main(String[] args) {
Immutable obj = new Immutable(10, "Immutable Class Example");
System.out.println(obj.getVal1());
System.out.println(obj.getVal2());
}
}[/code]


Java – Run Garbage Collection Process

[code lang=”java”]public class RunTheGarbageCollector {

public static void main(String[] args) {

/*
* To run the garbage collector thread use
* public static void gc() method of System class.
*
* Please note that, calling this method only suggest JVM
* to run the garbage collection process. It does not guarantee
* that all eligible objects will be garbage collected.
*/

System.out.println("Suggesting VM to run garbage collector");
System.gc();
System.out.println("Suggested VM to garbage collect objects");
}

}[/code]