Java - Specific Classes / API
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Java - Specific Classes / API
Specific Classes / API
FileResource: accessing file on computer.
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create a FileResource:
new FileResource() : opens a dialog box prompting you to select a file on your computer
new FileResource("path/to/file.ext") : find a file on computer or within your BlueJ project
new FileResource(existingFile) : uses the given File (typically returned by using a DirectoryResource)
Method
.lines()
// provides access to the contents of this opened file one line at a time
for (String line : fr.lines()) { }
.words()
// provides access to the contents of this opened file one word at a time
for (String word : fr.words()) { }
.asString()
// returns the entire contents of this opened file as one String
String contents = fr.asString();
URLResource: accessing a web page.
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create a URLResource by giving it a complete URL, or web address
new URLResource("https://www.something.com/file.ext"),
// uses the given address to download the referenced file
new URLResource("https://www.something.com/file.ext"),
// uses the given address to download the referenced file
Method
.lines()
// provides access to the contents of this opened web page one line at a time
for (String line : ur.lines()) { }
.words()
// provides access to the contents of this opened web page one word at a time
for (String word : ur.words()) { }
.asString()
// returns the entire contents of this opened web page as one String
String contents = ur.asString();
DirectoryResource: choosing one or more files on your computer.
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// can only create a DirectoryResource with no parameters:
new DirectoryResource()
Method
.selectedFiles()
// provides access to each of the files selected by the user one at a time
for (File f : dr.selectedFiles()) { }
StorageResource: storing and accessing a list of strings of any length.
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// creating an empty StorageResource
new StorageResource()
// creates an empty list
new StorageResource(otherList)
// creates a list that is an exact copy of otherList
Method
.add(item)
// adds the given item to the end of the list of strings
sr.add("first!");
sr.add("next ...");
.size()
// returns the number of strings stored in this list
sr.size() // is 2 (after the example above)
sr.size() // is 0 (immediately after clear() is called)
.data()
// provides access to each string in the list one at a time
for (String item : sr.data()) { }
.contains(item)
// returns true only if the given item is in the list sr.contains("first!") is true
sr.contains("last") // is false
.clear()
// removes all strings from this list, making it empty
sr.clear();
StringBuilder
- string cannot change,
- StringBuilder can change,
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StringBuilder sb = new StringBuilder(“Hello”);
append
// Put String, int, char, etc.. on end
insert
// Insert String, int, char, etc... into middle
charAt
// Gets character at specified index
setCharAt
// Changes the character at specified index
toString
// Get back String that you made
Character Building
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isLowerCase(ch)
// returns boolean if ch is 'a', 'b' …
isDigit(ch)
// returns boolean if ch is '0','1',…'9'
toLowerCase(ch)
// returns lowercase version of ch
toUpperCase(ch)
// returns uppercase version of ch
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