Friday, February 26, 2016


Strings are identifiers that are composed of one or many char identifiers, they can hold a big amount of characters and can be modified within a program in an amount of ways. a usual string is created in this way: String str1 = "Hello World";   It is very important that String is capitalized, that it's variable is stated with a quotation mark for both starting and beginning the string and that it ends with a semicolon.
Print method.
The print method is a method from the java.util.Object class in java that is the main class from which you import statements and methods from. It allows you to use String, String manipulation methods, the Print methods, and other equally important methods.
The print method is stated like this:
System.out.print("This is a print");
This will print the words "This is a print" to console. This is often used outside of the Graphic interfaces of programs for debugging purposes.
There are different methods that are used to manipulate String objects: charAt(), substring(), contains(), indexOf(), concat(), equals(), length(), trim(), etc.
These are used for different purposes, charAt(int) will find a char type data at a certain index from the string on which is used, it has parameters of int which means that you need to introduce an int and it will find the character from that position.
The method substring(int, int) requires two integers one for the beginning of the sub string and one for the end, it will take a chunk from between the two given indexes.
The method contains(String) has a String parameter and will find if the string it's used on has a sub string with the exact composition of the parameter string and will give it back as a boolean.
To find an index of a sub-string or a char then you use the indexOf(String) method which will return an int.
The method concat(String) allows you to concatenate two strings together, it will add the parameter string into the string to which the method is used.
equals(String) is the most secure way to see if two strings are equal to each other instead of using the == identifier.
length() will return an int with the number of characters that are in a single string variable.
trim() will erase from a string any excess white space from before or after a string.
REMEMBER: every time you modify a String object the String class does not dump the previous object instead it creates a new one and saves the other one.

String a = "\'a small fox sleeps\'"; if(a.contains("fox")){System.out.print(a);}
This will print: 'a small fox sleeps' to the console.

Apart from manipulating Strings with those three methods it is also possible to turn other primitive data to Strings. The method toString() from the class of any primitive data will turn it to Strings:
Integer.toString(), Double.toString(), Boolean.toString(), etc.

Friday, February 12, 2016


The while and for loops are the most important types of loops, and the most commonly used, there is also an advanced for loop called the for each loop but arrays are needed for it.
The while loop is a loop that keeps doing the code inside it until it's conditional is false.

boolean end = false;
int point = 0;
point ++;
if(point > 10){
//this will run the loop until points is 10

As well as there being a for loop which runs the loop until the conditional say x < 10 reaches false, but is written differently than the while loop and is more controllable.

int point = 0;
for(int i = 0; i < 10; i++){
//this program will run the loop ten times and will print on the console numbers from 1 to 11
// this is because the value of point is increased before the print statement

Loops are allowed to be inside of each other and you can use multiple combinations of the code to achieve different outcomes.

for(int i = 0; i < 10; i++){
if(point > 30){
end = true;
//this will run the loops until point is 30, the for loop will run 30 times and the while loop 3 times

For the next loop you will need to know about arrays, which is another post in this blog. After knowing about arrays you can use the for each loop, which loops for every array object or value.

int[] array = new int[4];
for(int arr : array){
arr = 3;
//this sets every int of the array to the number 3
//for-each loops are useful for scrolling around arrays quickly

String[] array = {"This", "is", "an", "array"}

Arrays and matrices are essential in Java programming, and programming in general. they are groups of variables or objects that hold different data in them.
a single array holds as many variables of the same data requirements that you need.

int[] array = new int[7];
int x = 1;
for(int i : array){
 i = x;
//this program will create an array of integers

There are different ways to instantiating an array
String[] names = {"Edward", "Joseph", "Smigla"};
for(String name : names){
System.out.print(name + " ");
//this code will print: Edward Joseph Smigla on the console
//you can also pull any variable from an array using the index
names[1] = "E.";
names[1] = "J.";
names[1] = "Shmigs";
for(String name : names){
System.out.print(name + " ");
}//this code will print: E .J. Shmigs on the console
//the index of the arrays is in programmer numbers 0 - 2 for arrays with 3 indexes
//always decreasing the index number by one from the amount of indexes

you can also create arrays of objects such as this:
public Integer[] array = new Integer[32];
for(int i = 0; i < array.length(); i++){
array[i] = (int)(Math.random()*32);
}//Remember to cast because Math.random() give a double //variable
// you do not need to use the for-each loop to cycle through arrays, you can also use the length()
//method, which finds the length of the array given  and returns it

You can also create arrays of arrays which are called matrices or 2D arrays (you can create as many arrays of arrays as needed)

int[][] numbers = new int[5][5];//this will create a 2D array containing 25 int variables
for(int i = 0; i < array.length(); i++){
for(int j = 0; j < array[i].length(); j++){
array[i][j] = (int)(Math.random() * 25);
System.out.print(array[i][j] + " ");
}//to give values to multiple index arrays you need multiple loops
//this will print random values from 0 - 24, 25 times (with a space in between and a new line every //five variables)

Matrices can be instantiated in different ways like the simple array.

int[][] numbers = {{1,2,3},{4,5,6},{7,8,9}};
//this instantiates a 2D array with the variables 1,2,3,4,5,6,7,8, and 9. in different levels of the array

Monday, February 8, 2016

If, Else Statements, and Switch.

If are ways to chose conditionals this can relate directly into real life, for example the problem about milk and eggs, when you go to the store and want to buy milk and eggs you first have to know whether there are milk and eggs. This problem in code would be solved with conditional statements:
int milk = 0;
boolean eggs = true;
if (eggs){
milk = 6;
//That indicates what the programmer in the picture thought of //when going to the store
milk = 1;
After this you have to make up an alternative to your condition just to make sure that if the condition is false then you are able to get a controlled result this is achieved with an else statement, for the else statement you do not need a condition because one was already stated, however you can use another if statement to add a condition.
int milk = 0;
int eggs = 20;
if (eggs > 0){
milk = 6;
}else if (eggs < 0){
milk = 1;
//This will identify that if there is more than 0 eggs there will be 6 bottles of milk, however if there is //no eggs the you'll only buy 1 bottle of milk.
Switch statements help identify different conditionals.
int milk = (int)(Math.random() * 6);//Will randomize the amount of milk from 0-6, remember casting
int eggs;
case 1: eggs = 1;
case 2: eggs = 2;
case 3: eggs = 3;

default : eggs = 4;
This conditional will check the value of milk and will compare it to the different cases that it's given, which will help indicate what block of code to activate, the "break" statement helps finishing the statement, without it the program would do the cases under the one without break until finding a break or a default statement, for example in the case 3 it would assign eggs to the value of 3, but then it would do the default case which assign eggs to 4.