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57 Cards in this Set
- Front
- Back
array |
an object that can store a group of values all of the same type |
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size declarator |
number inside the brackets when you declare an array |
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once an array is created |
the size of the array can not be changed |
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subscript |
used as an index to pinpoint a specific element within an array |
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bounds checking occurs at |
runtime |
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if an array is out of bounds |
an exception is thrown and immediately terminates |
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length field |
contains the number of elements in an array |
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largest subscript |
in an array is length-1 |
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enhanced for loop |
designed to iterate once for every element in an array, each time the loop iterates it copies an array element to a variable |
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for(int val: Numbers) System.out.println(val); what is the purpose of val? |
it receives the value of the array element temporarily each time the loop iterates
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array1 == array2 |
does not copy the array, makes a copy of the address that is stored in array 1 |
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reference copy |
when two variables reference the same array |
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to copy an array |
you need to copy each individual element of the array |
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when passing an array to a method |
it is passed just as an object is, actual array is not passed but a reference to the array is |
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ture or false, arr1 == arr2 |
always will be false because they have 2 different memory addresses |
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when a partially filled array is passedc as an argument to a method |
the variable that holds the count of items must also be passed as an argument |
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an array of string objects |
is really an array of references to string objects |
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sequential search algorithm |
compares each element w/ the value being searched for and stops when the value is found |
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2d array |
an array of arrays composed of rows and columns |
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int[][] numbers = { {1, 2, 3} {4, 5, 6} {7, 8, 9}}; numbers.length equals? |
3( # of rows) |
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ragged array |
when rows of a 2d array are different lengths |
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selection sort algorithm |
smallest value in an array is located and moved to element 0, switching with the element that was stored there |
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ArrayList |
an object that is an array of objects |
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to add items to arraylist |
arraylist.add("James"); |
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to get the number of items stored in arraylist |
arraylist.size(); |
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default capacity of arraylist |
10, without changing it manually |
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given an array named x, a reference to x[x.length] |
causes an indexoutofboundsexception |
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how many bytes if each reference is 4? int[] a = new int[10]; int[b] = a; |
48 |
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an enhanced for loop |
cannot be used to change array elements |
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arraylist size and capacity |
size <= capacity |
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to reference the last element of arraylist |
list.get(list.size() - 1) |
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Wrapper class |
a class that is wrapped around a primitive data type and allows you to create objects instead of variables |
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immutable |
once an object is created value can not be changed |
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tokenizing |
the process of breaking a string down into components(tokens) |
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delimeter |
character that separates tokens |
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split |
tokenizes a string and returns an array of string objects |
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input file |
file that a program reads data from, serves as input to the program |
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output file |
file that a program writes data to, program stores output |
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text file |
contains data that has been encoded as tet using unicode |
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binary file |
contains data that has not been converted to text |
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printWriter |
a class that allows you to open a file for writing |
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printWriter outputFile = new PrintWriter("Data.txt"); |
passes the name of the file you want to open |
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if the file you are opening already exists |
it will be erased an an empty file with the same name will be created |
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outputFile.close(); |
closes file when done writing, writes any unsaved data remaining in the file buffer |
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buffer |
a small holding section of memory when it is filled all the memory that is stored there is written to the file |
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exception |
a signal indicating that the program cannot continue until the unexpected even has been dealt with |
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fileWrtier |
used to append data to an existing file |
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binary file |
a file that contains data that is not readable in text form is called a(n) |
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printwriter |
The best class to use for writing a file is |
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Every output file should be explicitly closed after the last write operation so that |
the buffer will be written out to the file |
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IOException
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When an error occurs during file output, the program will thrown a(n) |
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PrintWriter output = new PrintWriter(new FileWriter(“filename.txt”, true)); |
The correct way to open a file for extension (to append to the file) is: |
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/home/username/myfile.txt |
The correct form in which to specify a file on a Unix system is |
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C:\\Users\\username\\myfile.txt |
the correct form in which to specify a file on a Windows system is
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The correct way to open a file to be read using Scanner is |
Scanner input = new Scanner(new File(“filename.txt”)); |
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if (inputFile.exists()) {…} |
The Scanner method to detect whether a file exists is |
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while (inputFile.hasNext()) {…} |
The correct way to setup an input loop with Scanner is |