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Add generic n array concatenation snippet

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Lines changed: 21 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -11,6 +11,7 @@ Update the sample application with the snippet and add a test for it. After prov`
`11`	`11`
`12`	`12`	`###Array`
`13`	`13`	`*[Generic two array concatenation](#generic-two-array-concatenation)`
	`14`	`+*[Generic N array concatenation](#generic-N-array-concatenation)`
`14`	`15`
`15`	`16`	`##Array`
`16`	`17`
`@@ -25,3 +26,23 @@ Update the sample application with the snippet and add a test for it. After prov`
`25`	`26`	```
`26`	`27`
`27`	`28`	`[⬆ back to top](#table-of-contents)`
	`29`	`+`
	`30`	`+###Generic N array concatenation`
	`31`	`+`
	`32`	+```java
	`33`	`+publicstatic<T>T[] nArrayConcat(T[] first,T[]... rest) {`
	`34`	`+int totalLength= first.length;`
	`35`	`+for (T[] array: rest) {`
	`36`	`+ totalLength+= array.length;`
	`37`	`+ }`
	`38`	`+T[] result=Arrays.copyOf(first, totalLength);`
	`39`	`+int offset= first.length;`
	`40`	`+for (T[] array: rest) {`
	`41`	`+System.arraycopy(array,0, result, offset, array.length);`
	`42`	`+ offset+= array.length;`
	`43`	`+ }`
	`44`	`+return result;`
	`45`	`+ }`
	`46`	+```
	`47`	`+`
	`48`	`+[⬆ back to top](#table-of-contents)`

Lines changed: 22 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -18,4 +18,26 @@ public static <T> T[] arrayConcat(T[] first, T[] second) {`
`18`	`18`	`System.arraycopy(second,0,result,first.length,second.length);`
`19`	`19`	`returnresult;`
`20`	`20`	`}`
	`21`	`+`
	`22`	`+/**`
	`23`	`+ * Generic N array concatenation`
	`24`	`+ * Credits: Joachim Sauer https://stackoverflow.com/questions/80476/how-can-i-concatenate-two-arrays-in-java`
	`25`	`+ * @param first is the first array (not null)`
	`26`	`+ * @param rest the rest of the arrays (optional)`
	`27`	`+ * @param <T> the element type`
	`28`	`+ * @return concatenated array`
	`29`	`+ */`
	`30`	`+publicstatic <T>T[]nArrayConcat(T[]first,T[]...rest) {`
	`31`	`+inttotalLength =first.length;`
	`32`	`+for (T[]array :rest) {`
	`33`	`+totalLength +=array.length;`
	`34`	`+ }`
	`35`	`+T[]result =Arrays.copyOf(first,totalLength);`
	`36`	`+intoffset =first.length;`
	`37`	`+for (T[]array :rest) {`
	`38`	`+System.arraycopy(array,0,result,offset,array.length);`
	`39`	`+offset +=array.length;`
	`40`	`+ }`
	`41`	`+returnresult;`
	`42`	`+ }`
`21`	`43`	`}`

Lines changed: 17 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -22,4 +22,21 @@ public void testArrayConcat() {`
`22`	`22`	`// expected behaviour, everything is fine`
`23`	`23`	`}`
`24`	`24`	`}`
	`25`	`+`
	`26`	`+/**`
	`27`	`+ * Tests for {@link Library#nArrayConcat(Object[], Object[][])}`
	`28`	`+ */`
	`29`	`+@Test`
	`30`	`+publicvoidtestNArrayConcat() {`
	`31`	`+Integer[]single =Library.nArrayConcat(newInteger[1]);`
	`32`	`+assertEquals(single.length,1);`
	`33`	`+String[]multiple =Library.nArrayConcat(newString[5],newString[12],newString[3],newString[8]);`
	`34`	`+assertEquals(multiple.length,28);`
	`35`	`+try {`
	`36`	`+Double[]doubles =Library.nArrayConcat(null,null,null,null);`
	`37`	`+fail();`
	`38`	`+ }catch (NullPointerExceptione) {`
	`39`	`+// expected behaviour, everything is fine`
	`40`	`+ }`
	`41`	`+ }`
`25`	`42`	`}`

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