knowledge/awesome-cheatsheets
1
1
Fork 0
mirror of https://github.com/namibia/awesome-cheatsheets.git synced 2024-12-22 10:08:54 +00:00
Code Issues Releases Activity

Merge branch 'master' of github.com:LeCoupa/awesome-cheatsheets

Browse Source
This commit is contained in:
Julien Le Coupanec 2022-04-15 22:01:16 +02:00
commit 2137ac0559
1 changed files with 33 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

66
languages/java.md
View File

@ -12,12 +12,12 @@ public class HelloWorld {
### COMPILATION & EXECUTING JAVA CODE
* Goto your program directory in terminal (Assumed JAVA Path is set)
* Go to your program directory in terminal (Assumed JAVA Path is set)
* After for compile your code
> **javac HelloWorld.java (your program file name)**
* For run program
* For run program
> **java HelloWorld (main class name)**
@ -61,13 +61,13 @@ int c = a + b;
### PRINTING
```java
String s = "Happy Coding Folks!!"
void System.out.print(String s) //print s
void System.out.println(String s) //print s, followed by a newline
void System.out.println() //print a newline
System.out.print(String s) //print s
System.out.println(String s) //print s, followed by a newline
System.out.println() //print a newline
```
### PARSING COMMAND-LINE ARGUMENTS
```java
```java
String s = "Java is the best!!"
int Integer.parseInt(String s) //convert s to an int value
double Double.parseDouble(String) //convert s to a double value
@ -111,12 +111,12 @@ int c = a + b;
if (x>y) { // x > y is the boolean expression
//Sequence of statements
x = y;
}
}
```
> IF-ELSE STATEMENT
```java
if (BOOLEAN EXPRESSION) {
if (BOOLEAN EXPRESSION) {
//Sequence of statements
} else {
//Sequence of statements
@ -125,7 +125,7 @@ int c = a + b;
> NESTED IF STATEMENT
```java
if (BOOLEAN EXPRESSION) {
if (BOOLEAN EXPRESSION) {
//Sequence of statements
} else if {
//Sequence of statements
@ -189,7 +189,7 @@ int c = a + b;
{
//Statement
}
```
```
**Example:**
```java
for (int i = 0; i <= n; i++) {
@ -197,7 +197,7 @@ int c = a + b;
}
```
>Enhanced for loop/for-each
>Enhanced for loop/for-each
```java
for(dataType item : array) {
...
@ -208,8 +208,8 @@ for(dataType item : array) {
```java
// array of numbers
int[] numbers = {100, 200, 300, 400};
// for each loop
// for each loop
for (int number: numbers) {
System.out.println(number);
```
@ -217,7 +217,7 @@ for(dataType item : array) {
> WHILE LOOP STATEMENT
```java
while(condition){ //till condition will be true.
//code to be executed
//code to be executed
}
```
**Example:**
@ -245,7 +245,7 @@ for(dataType item : array) {
do{
System.out.println(i);
i++;
}while(i<=10);
}while(i<=10);
```
### ARRAY
@ -273,19 +273,19 @@ for(dataType item : array) {
### ACCESS MODIFIERS
1. defualt(No keyword required)
1. defualt(No keyword required)
2. private
3. public
4. protected
4. protected
### NON ACCESS MODIFIERS
1. static
2. final
1. static
2. final
3. transient
4. abstract
5. synchronized
6. volatile
6. volatile
## Object Oriented Programming (OOPs) Concept :clipboard:
@ -324,7 +324,7 @@ for(dataType item : array) {
### CLASS DECLARATION
```java
class MyClass {
// field, constructor, and
// field, constructor, and
// method declarations
}
```
@ -377,11 +377,11 @@ class MyClass extends MySuperClass implements YourInterface {
```java
public class Bicycle{
private int gear;
private int cadence;
private int speed;
public Bicycle(int startCadence, int startSpeed, int startGear) { //args-constructor
gear = startGear;
cadence = startCadence;
@ -396,13 +396,13 @@ class MyClass extends MySuperClass implements YourInterface {
### POLYMORPHISM
* Polymorphism is the concept where an object behaves differently in different situations.
* There are two types of polymorphism
1. compile time polymorphism
* There are two types of polymorphism
1. compile time polymorphism
2. runtime polymorphism.
#### 1. Compile Time Polymorphism
* Compile-time polymorphism is achieved by method overloading.
* method overloading is creating multiple method with methods name is same and arguments are different.
* method overloading is creating multiple method with methods name is same and arguments are different.
```java
public class Circle {
@ -461,7 +461,7 @@ class MyClass extends MySuperClass implements YourInterface {
### INHERITANCE
* Inheritance is the mechanism of code reuse.
* Inheritance is the mechanism of code reuse.
* The object that is getting inherited is called the superclass and the object that inherits the superclass is called a subclass.
* We use `extends` keyword in java to implement inheritance from class.
* We use `implements` keyword in java to implement inheritance from interface.
@ -488,7 +488,7 @@ class MyClass extends MySuperClass implements YourInterface {
* Abstraction can be achieved by two ways.
1. Abstract Class
2. Interface
#### 1. Abstract Class
* An abstract class must be declared with an `abstract` keyword.
* It can have abstract and non-abstract methods.
@ -499,7 +499,7 @@ class MyClass extends MySuperClass implements YourInterface {
```java
abstract class Flower{
abstract String Smell(); //abstract method.
String Oil(){ // non-abstract method.
String Oil(){ // non-abstract method.
System.out.println("Flower Oil is good.");
}
}
@ -535,7 +535,7 @@ class MyClass extends MySuperClass implements YourInterface {
* As in encapsulation, the data in a class is hidden from other classes, so it is also known as **data-hiding**.
* Encapsulation can be achieved by Declaring all the variables in the class as private and writing public methods in the class to set and get the values of variables.
* Best example of Encapsulation is POJO (Plain-Java-Object-Class).
```java
public class User {
private String username;
@ -558,7 +558,7 @@ class MyClass extends MySuperClass implements YourInterface {
}
}
```
## ADVANCE DATA TYPE
* **STACK DATA TYPE**
@ -591,7 +591,7 @@ class MyClass extends MySuperClass implements YourInterface {
//import Iterator
import java.util.Iterator;
public class Queue<Item> implements Iterable<Item> {
public class Queue<Item> implements Iterable<Item> {
//FIFO queue
private Node first;