【Java】Copy array

ref:
http://www.programcreek.com/2015/03/system-arraycopy-vs-arrays-copyof-in-java/
http://openhome.cc/Gossip/JavaEssence/EqualOperator.html
http://toyangel.pixnet.net/blog/post/27163971

可以使用
int[] newArray = Arrays.copyOf(oldArray,newArray length);

那它和System.arraycopy()有何差別
可以參考以下範例：

System.arraycopy()

int[] arr = {1,2,3,4,5};   int[] copied = new int[10]; System.arraycopy(arr, 0, copied, 1, 5);//5 is the length to copy   System.out.println(Arrays.toString(copied));

Output:

[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
[0, 1, 2, 3, 4, 5, 0, 0, 0, 0]

Arrays.copyOf()

int[] copied = Arrays.copyOf(arr, 10); //10 the the length of the new array System.out.println(Arrays.toString(copied));   copied = Arrays.copyOf(arr, 3); System.out.println(Arrays.toString(copied));

Output:

[1, 2, 3, 4, 5, 0, 0, 0, 0, 0]
[1, 2, 3]

以下廢言，因為有這些錯誤，所以才特別筆記了這一篇。
--------------------------------------------------------------------------------
之前犯了低級錯誤，浪費不少時間。

依照記憶寫的，原本想要複製陣列：
很直覺就寫下
old array =xxxx;
new array = old array
當然這省略一些步驟加上這只是pseudo code而以。
所以想當然爾，每次old array改變時，new array也會跟著改變。(因為new array 是指向 old array的reference value → call by value)

【Android】Autoincrement VersionCode with gradle extra properties

ref:
http://stackoverflow.com/a/21405744
https://github.com/commonsguy/cw-omnibus/tree/master/Gradle/HelloVersioning

down voteaccepted

I would like to read the versionCode from an external file I am sure that there are any number of possible solutions; here is one: android { compileSdkVersion 18 buildToolsVersion "18.1.0" def versionPropsFile = file('version.properties') if (versionPropsFile.canRead()) { def Properties versionProps = new Properties() versionProps.load(new FileInputStream(versionPropsFile)) def code = versionProps['VERSION_CODE'].toInteger() + 1 versionProps['VERSION_CODE']=code.toString() versionProps.store(versionPropsFile.newWriter(), null) defaultConfig { versionCode code versionName "1.1" minSdkVersion 14 targetSdkVersion 18 } } else { throw new GradleException("Could not read version.properties!") } // rest of android block goes here } This code expects an existing version.properties file, which you would create by hand before the first build to have VERSION_CODE=8.

【Tool】( Bitbucket && SourceTree ) || ( Android Studio && Source Tree )

ref:
https://ukyoappdev.blogspot.tw/2015/01/macandroid-studiogitbitbucket.html
https://www.gitbook.com/book/ptodue/test-test-test/details