A for each loop(or enhanced for loop) is used to traverse a array, but they can’t change the values of elements with a primitive datatype because the variable given refers to a element that holds a copy of the element.

A for each loop is made like ;

for( data/objectTypeOfTheElementsInTheArray varName : ArrayName)

{

. . . //process varName

}

Also do not use a for each loop if you need to access the indices, because the example above is basically equal to:

for( int i =0; i<arrayName.length;i++)

{

data/objectTypeOfTheElementsInTheArray varName = arrayName[ i ];

. . . //process varName

}

A common use of for each loops include finding the arrays smallest or largest value.

A two dimensional array normally represents something along the lines of a box or a chart, or something else in a grid format.

THis kind of array has two [ ] after its name when you are trying to call its index, the first [ ] should have the rows index the second [ ] should have the column index. THe rows are horizontal and  the columns are vertical, the number of columns per row can also differ. Both of the indexes start at zero.

You declare a two dimensional array in two ways:

• datatype[ ][ ]  arrayName = new datatype[numRows][numCols];
•  datatype[ ][ ]  arrayName =

{   

{somevalueA, somevalueB, . . . } ,

{somevalueC, somevalueD , . . . }

} ;

You can get the number of rows by doing arrayName.length.

And you can get the number of columns by doing m[rowNumber].length.

One dimensional arrays are arrays that only have a single index involved, so they are a row or a list not a box, table or chart.

You can make a one dimensional array in several ways as shown below:

• datatype[ ] arrayname= new datatype/object[sizeofarray];
• datatype[ ] arrayname= {variableA,variableB, . . };

You can find the size or length of a array by doing arrayName.length, this is like  calling a public variable not a method so there are no parenthesis.

You add a element to an array by doing :

arrayName[index] = <what you want to add to the array as long as its type is the same as the arrays>;

CodeHS user input uses a one line format.

THat format is:

datatype varname = readDatatype(“prompt”);

This may diifer if you are making a string variable in which case instead of readdatatype it is readLine.

An example of user input being used is

int l = readInt(“Eneter a positive interger”);

This information is also shown/explained in the docs of codeHS when you are making a program.

Eclipse does user input according to the given java packages on the oracle website, which is where you download eclipse.The specific java package is java.util.Scanner.  So, the first thing you need to do is import the package if the version of eclipse doesn’t import it automatically.

Which is done by doing:

import java.util.Scanner;

In the space before the class header along with any other imports.

The second thing you need to do is make a scanner object

Which is typically done in the public method and is done by a piece of code along the lines of:

Scanner varname= new Scanner(System.in);

The next step is to typically make the prompt. Which is normally done with:

System.out.print(“prompt”);

The final step is to turn the answer to the prompt into user input so doing something along the lines of:

int k = varname.nextInt();

So all together it is something along the lines of:

import java.util.Scanner;

public class Name

{

public static void main(String[] args)

{

Scanner varname= new Scanner(System.in);

System.out.print(“prompt”);

int k = varname.nextInt();

varname.close();

}

}

varname.close (); is just closing the scanner so you can’t put in anymore input, but I found it isn’t normally completely necessary.

The scanner class can also be used from what I can tell, since I have never used it this way personally, to get things from files on your computer or to take things out of a string by using the delimiter part of the class.

A link to the scanner package is below:

https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html

THere are two main kinds of comments single line and multi line,

An example of single line is:

//single line comment

A single line comment is often used to explain obscure code, so code where it isnt necessarily intuitive what it does.

A example of multi line is:

/**

*multi line comment

*

*

*/

Another form is:

/*

*

*/

The former example of multi-line comment are used for api documentation using the javadoc tool. While the latter is just a way to make a comment multiple lines and should be avoided as much as possible since it makes the code more clunky and generally the better pieces of programming  can easily be understood as long as you do api documentation.

The format for api documentation is basically

/**

*<p>explanation of method</p>

*@param parameter

*@param parameter

*@return what the return is suppose to be

*/

Although it differs depending on what it is for example normally there is a comment before the beginning of a class explaining the class’s purpose and who the author is.

The video on comments is below