Miscellaneous

Access Modifiers

Modifier	Class	Package	Subclass	World
public	Y	Y	Y	Y
protected	Y	Y	Y	N
no modifier	Y	Y	N	N
private	Y	N	N	N

Regular expressions

String text = "I am learning Java";
// Removing All Whitespace
text.replaceAll("\\s+", "");

// Splitting a String
text.split("\\|");
text.split(Pattern.quote("|"));

See: Regex in java

Comment

// I am a single line comment!

/*
And I am a
multi-line comment!
*/

/**
 * This
 * is
 * documentation
 * comment
 */

Keywords

• abstract
• continue
• for
• new
• switch
• assert
• default
• goto
• package
• synchronized
• boolean
• do
• if
• private
• this
• break
• double
• implements
• protected
• throw
• byte
• else
• import
• public
• throws
• case
• enum
• instanceof
• return
• transient
• catch
• extends
• int
• short
• try
• char
• final
• interface
• static
• void
• class
• finally
• long
• strictfp
• volatile
• const
• float
• native
• super
• while

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Math methods

Method	Description
Math.max(a,b)	Maximum of a and b
Math.min(a,b)	Minimum of a and b
Math.abs(a)	Absolute value a
Math.sqrt(a)	Square-root of a
Math.pow(a,b)	Power of b
Math.round(a)	Closest integer
Math.sin(ang)	Sine of ang
Math.cos(ang)	Cosine of ang
Math.tan(ang)	Tangent of ang
Math.asin(ang)	Inverse sine of ang
Math.log(a)	Natural logarithm of a
Math.toDegrees(rad)	Angle rad in degrees
Math.toRadians(deg)	Angle deg in radians

Try/Catch/Finally

try {
  // something
} catch (Exception e) {
  e.printStackTrace();
} finally {
  System.out.println("always printed");
}

Comments