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@ -28,11 +28,11 @@
>> **```String Concatenation```**: means that two strings are combined into one using the "r" sign >> **```String Concatenation```**: means that two strings are combined into one using the "r" sign
> ## Varaibles > ## Varaibles
>> Holder for data > - Holder for data
>> We can use words instead of just a single letter > - We can use words instead of just a single letter
>> - can store more than just numbers > - can store more than just numbers
>> a place in memory (RAM: random access memory) where it can be stored or referred to > - a place in memory (RAM: random access memory) where it can be stored or referred to
>> - Name, type, value > - Name, type, value
>> To declare a variable >> To declare a variable
>> 1. Name >> 1. Name
@ -109,9 +109,12 @@
>>> **Remember** ```String``` is not a primitive type >>> **Remember** ```String``` is not a primitive type
>> String - object data type
>> ```equals(String)```
>> ### Boolean Expressions >> ### Boolean Expressions
>>> can only have 2 possible value(true or false) >> - can only have 2 possible value(true or false)
>>> - compare must be compatible type >> - compare must be compatible type
>>> |Symbol|Meaning| >>> |Symbol|Meaning|
>>> |:-----|:------| >>> |:-----|:------|
@ -152,8 +155,8 @@
> ## Selection statements > ## Selection statements
>> allow java to make a decision > - allow java to make a decision
>> depending on decision, program will function differently each time it is run > - depending on decision, program will function differently each time it is run
>> ```java >> ```java
>> if(condition){ >> if(condition){
@ -174,8 +177,8 @@
>>>``` >>>```
>> ### ```=``` vs ```==``` >> ### ```=``` vs ```==```
>>> ```=```: assignment >> - ```=```: assignment
>>> ```==```: comparison >> - ```==```: comparison
>> ### if.... else if.... else >> ### if.... else if.... else
@ -193,11 +196,11 @@
>>> } >>> }
>>> ``` >>> ```
>>> - used when program needs to choose from a variety of situations >> - used when program needs to choose from a variety of situations
>>> - use else if to specify another condition >> - use else if to specify another condition
>>> - helps to control the flow of your program >> - helps to control the flow of your program
>>> - helps make decision when 3 or more conditions must be considered >> - helps make decision when 3 or more conditions must be considered
>>> - makes program more efficient >> - makes program more efficient
>>> ```java >>> ```java
>>> if(age >= 16){ >>> if(age >= 16){
@ -243,7 +246,7 @@
>> **```NOT```**: flips the value of a statement >> **```NOT```**: flips the value of a statement
>> ### Truth Table >> ### Truth Table
>>> Used to study logic by computer scientists >> - Used to study logic by computer scientists
>>> | X | Y |X OR Y|X AND Y| >>> | X | Y |X OR Y|X AND Y|
>>> |:--|:--|:-----|:------| >>> |:--|:--|:-----|:------|
@ -269,9 +272,9 @@
>> ``` >> ```
>> ### While Loops >> ### While Loops
>>> consists of a condition statement that are executed while the condition is true >> - consists of a condition statement that are executed while the condition is true
>>> types of conditions used in a while statement are the same as in the ```if statement``` >> - types of conditions used in a while statement are the same as in the ```if statement```
>>> while the condition is true, repeat the statements in the loop >> - while the condition is true, repeat the statements in the loop
>>> ```java >>> ```java
>>> while(num <= 10){ >>> while(num <= 10){
@ -280,10 +283,10 @@
>>> } >>> }
>>> ``` >>> ```
>>> the program continues repeating until the num is greater than 10 >> - the program continues repeating until the num is greater than 10
>>> there may be times when you may want to specify more than one condition >> - there may be times when you may want to specify more than one condition
>>> no limit to the number of conditions, but should limit to 2 or 3 >> - no limit to the number of conditions, but should limit to 2 or 3
>>> can combine conditions(logical statements) using ```&&``` and ```||``` conditional operators >> - can combine conditions(logical statements) using ```&&``` and ```||``` conditional operators
>>> ```java >>> ```java
>>> while(num >= 1 && num <= 10){ // runs until num is between 1 and 10 >>> while(num >= 1 && num <= 10){ // runs until num is between 1 and 10
@ -316,11 +319,11 @@
>> ### For Loops >> ### For Loops
>>> include three distinct statements separated by semicolon >> - include three distinct statements separated by semicolon
>>> first statement declares the counter variable >> - first statement declares the counter variable
>>> second statement specifies exit condition >> - second statement specifies exit condition
>>> third statement increments the counter variable after each iteration of the loop >> - third statement increments the counter variable after each iteration of the loop
>>> counter variable only exists within loop >> - counter variable only exists within loop
>>> ```while``` and ```for``` loop: - may not need to run if condition is false >>> ```while``` and ```for``` loop: - may not need to run if condition is false
@ -331,15 +334,15 @@
>>> ``` >>> ```
>> ### Accumulator >> ### Accumulator
>>> variables that add any value to a sum or total >> - variables that add any value to a sum or total
>>> realize the need for the variable >> - realize the need for the variable
>>> declare the variable >> - declare the variable
>>> initialize it (give it a start value, usually 0) >> - initialize it (give it a start value, usually 0)
>>> accumulate the value in a loop (add the value to the variable) >> - accumulate the value in a loop (add the value to the variable)
>> ### Do while Loop >> ### Do while Loop
>>> They must runu minimum once >>> They must run minimum once
>>> After running once, it checks the continue condition at the end of the iteration >>> After running once, it checks the continue condition at the end of the iteration
>>> ```java >>> ```java
@ -390,9 +393,101 @@
> ```Arrays```: a data structure that allow you to hold multiple pieces of data, in a single object > ```Arrays```: a data structure that allow you to hold multiple pieces of data, in a single object
> - hold a predetermined number of elements > - hold a predetermined number of elements
> - must be same type > - must be same type
> ``` java
> int, String, char, boolean, double, complex types
> ```
> - [] - square brackets means index
> - arrays always start at 0 index
> - must be assigned a fixed size
> - use counted loop with array to do things
> ## Example:
>> ```java
>> // declare an array of 5 integer
>> int [] numArray = new int[5];
>> // set the 0 index of numArray to 123
>> numArray[0] = 123;
>> // get the array size
>> int arraySize = numArray.length;
>> ```
> ### Mid - program initialization of arrays
> - can declare the array at the beginning ant set size
> - All variable and arrays must be declared at the beginning of the program for proper conventions
>> ```java
>> // declare variables and array
>> String[] names;
>> int numValues;
>> System.out.println("How many names?");
>> numValues = scan.nextInt();
>> // initialize array
>> names = new String[numValues];
>> ```
# Unit 3: Sorting
- ```sorting```: the process of arranging a list of items into a well-defined order
- final list rearrangement of the original list
> ## Bubble Sort
> - when x numbers in array, loop x - 1 times
> - The bubble sort algorithm works by swapping adjacent pairs in the list until all adjacent pairs are sorted in order, at which the entire list is sorted
> - by making passes through the array, each pass moves from left to right
> - the first pass compares element 1 and element 2 and swaps them if they are out of order, then compares element 2 and element 3 and swaps them if they are out of order, and so on
> - the largest element is moved to the right
> - for a length of n, there are n - 1 passes
>> |Pass 1|Pass 2|Pass 3|Pass 4|
>> |:-----|:-----|:-----|:-----|
>> |```3 6``` 5 4 2|```3 5``` 4 2 6|```3 4``` 2 5 6|```3 2``` 4 5 6|
>> |3 ```6 5``` 4 2|3 ```5 4``` 2 6|3 ```4 2``` 5 6|2 3 4 5 6|
>> |3 5 ```6 4``` 2|3 4 ```5 2``` 6|3 2 4 5 6|
>> |3 5 4 ```6 2```|3 4 2 5 6|
>> |3 5 4 2 6|
>> |Number of Elements|Number of Passes|Number of Comparisons|
>> |:-----------------|:---------------|:--------------------|
>> |4|3|6|
>> |5|4|10|
>> |6|5|15|
>> |7|6|21|
>> |8|7|28|
>> |9|8|36|
>> |10|9|45|
>> |```n```|```n - 1```|```n * (n - 1) / 2```|
> ## Algorithm
>> ```
>> repeat the following n -1 times
>> for each element in the array, starting at the first element
>> compare items in current positions with the element in the next position
>> if item in current position is greater than item in next position then
>> swap the 2 items using the following steps
>> temp = current list item
>> current list item = next list item
>> next list item = temp
>> ```
> ## Code
>> ```java
>> // array called list
>> for (int i = 0; i < list.length - 1; i++){
>> for(int j = 0; j < list.length - 1 - i; j++){
>> if(list[j] > list[j + 1]){
>> int temp = list[j];
>> list[j] = list[j + 1];
>> list[j + 1] = temp;
>> }
>> }
>> }
>> ```
> ```CompareTo(String)```
> - result si a ```negative integer``` if this String object lexicographically(alphabetically) precedes the argument string
> - result is a ```positive integer``` if this string object
> - result is ```zero``` if the string are equal