types of functions in java
types of functions in java
I'm happy to provide a detailed answer in English!
Java is an object-oriented programming language that supports multiple programming paradigms, including procedural, functional, and imperative programming. In Java, a function is a block of code that can be invoked repeatedly with different inputs. Here are some types of functions in Java:
Method: A method is a function that belongs to a class and is used to perform a specific task. Methods can take arguments, return values, and access the instance variables of the class.Example: public void sayHello(String name) { System.out.println("Hello " + name); }
Example: public MyClass(int x, int y) { this.x = x; this.y = y; }
Example: public static void printHello() { System.out.println("Hello"); }
Example: Runnable r = () -> System.out.println("Hello");
Example: interface Print { void print(String s); }
Example: public class Outer { public class Inner { public void sayHello() { System.out.println("Hello"); } } }
Example: public void main(String[] args) { int x = 5; method(x); } public void method(int y) { System.out.println(y); }
Example: public void main(String[] args) { new Runnable() { public void run() { System.out.println("Hello"); } }.run(); }
These are some common types of functions in Java. Functions play a crucial role in Java programming, and understanding their types is essential for writing efficient, readable, and maintainable code.
Remember: "Code should be written to be understood by humans first, and machines second." - Alan Perlis
java functions list
Here are some common Java functions that you can use:
String Functions:
toLowerCase()
: converts a string to lowercase. toUpperCase()
: converts a string to uppercase. concat(String s)
: concatenates a string with another string. substring(int beginIndex, int endIndex)
: returns a subset of characters from the original string. indexOf(String str)
: finds the index of the first occurrence of a specified value within an array. lastIndexOf(String str)
: finds the index of the last occurrence of a specified value within an array. split(String regex)
: splits this string around matches of the given regular expression. trim()
: removes whitespace from both ends of a string. replace(String oldPattern, String newPattern)
: replaces all occurrences of the first argument with the second.
Math Functions:
abs(int a)
: returns the absolute value of an integer. ceil(double a)
: returns the smallest integer that is greater than or equal to the input value. floor(double a)
: returns the largest integer that is less than or equal to the input value. max(double a, double b)
: returns the maximum value of two numbers. min(double a, double b)
: returns the minimum value of two numbers. pow(double a, double b)
: calculates the power of one number raised to another. random()
: returns a pseudorandom number in the range 0.0 through 1.0. sqrt(double a)
: calculates the square root of a number.
Array Functions:
length()
: returns the size of an array. get(int index)
: returns the value at the specified position in an array. set(int index, int value)
: assigns a new value to the element at the specified position. equals(Object obj)
: checks whether two arrays are equal.
Date and Time Functions:
format(String format)
: formats a date according to a given pattern. parse(String text)
: parses a string into a Date object. getTime()
: returns the current system time in milliseconds. sleep(long milliseconds)
: causes the calling thread to sleep for a specified period of time.
File and Directory Functions:
listFiles()
: returns an array of files that can be found within this directory. mkdir(String dir)
: creates a new directory with the specified name. delete()
: deletes the file or directory denoted by this abstract path name. exists()
: checks whether a file or directory exists.
Miscellaneous Functions:
className()
: returns the name of the class of which an invocation is part. getClass()
: returns the runtime class of this Java object. notify()
: resets the lock on this object and test whether it should be notified. wait(long timeout)
: causes the current thread to wait until either another thread invades the Object's critical section or a specified amount of real time has elapsed.
This is not an exhaustive list, but it gives you an idea of the types of functions available in Java.