From Android Developers : You can use a third party JAR in your application by adding it to your Eclipse project as follows: In the Package Explorer panel, right-click on your project and select Properties . Select Java Build Path , then the tab Libraries . Press the Add External JARs... button and select the JAR file. Alternatively, if you want to include third party JARs with your package, create a new directory for them within your project and select Add Library... instead. It is not necessary to put external JARs in the assets folder. Apparently, this is not working for me! I added a libs folder, put the external jar in libs . The project built fine, but the APK does not include the...

RFC 1918 reserved three blocks of IP addresses for private internets. These come in handy when you create an internal IP network. Range RFC 1918 Name Description 10.0.0.0 - 10.255.255.255 24-bit block A single class A network number 172.16.0.0 - 172.31.255.255 20-bit block 16 contiguous class B network numbers 192.168.0.0 - 192.168.255.255 16-bit block 256 contiguous class C network numbers

Read the whole contents of a file into a String. It's better to read the whole file as bytes and convert to String than to read the file line by line and concatenate the lines. String getFileContents(String fileName) throws... Using java.nio : import java.io.FileInputStream; import java...

Some methods to search for a substring within a string: To know that a substring indeed exists within a string: boolean found = wholeString.contains(substring); To find where the substring is contained: int index = wholeString.indexOf(substring); If the substring is regex: boolean match = wholeString.matches(".*" + substri... Case insensitive match: convert both whole string and substring to lowercase, then compare. Or, use case insensitive flag for regex. Test code: import java.util.regex.*; public class Stri...

This is how to split a string using java.util.StringTokenizer : StringTokenizer tok = new StringTokenizer("this \... But don't do it ! According to JavaDoc : StringTokenizer is a legacy class that is retained for compatibility reasons although its use is discouraged in new code. It is recommended that anyone seeking this functionality use the split method of String or the java.util.regex package instead. Using String.split , the equivalent code is: String[] tokens = "this \tis\n a\t test".split("\... Also note that the following yield different results: String[] tokens1 = "this \tis\n a\t test".split("...

The one argument version of String.split omits trailing empty strings. To get all parts, including trailing empty strings, you need to use the two argument version with a negative limit : public class TestStringSplit { public stati... Output: Length of array: 8 Part[0]: '1' Part[1]: '2'...

Sample code: import java.util.*; public class TestArrayL... If you use iterators, the for loop is equivalent to: for (Iterator<String> i = l.iterator(); i.hasNext(... The simplified for loop (or, for-each loop) can be used for arrays or objects that implement java.lang.Iterable . Note that by using generics, there's not need to down cast. But new for loop syntax doesn't down cast either. If List<String> is changed tp List<Object> , the code doesn't compile.

The goal is to read a file like this: for (String line: textFileReader) { // do s... This is the code: import java.io.*; import java.util.Iterator; ...

This code snippet import java.util.*; public class UncheckedCast ... fails with a compilation error and a warning: $ javac -Xlint:unchecked UncheckedCast.java Unc... Because List<String> is not a reifiable type, the Java Runtime does not have enough information to verify the type or do the type casting. This is fixed by changing List<String> to List<?> (or to the raw type List ): public static void main(String[] args) { Ob...

From the Java Language Specification : Because some type information is erased during compilation, not all types are available at run time. Types that are completely available at run time are known as reifiable types . A type is reifiable if and only if one of the following holds: It refers to a non-generic type declaration. It is a parameterized type in which all type arguments are unbounded wildcards. It is a raw type. It is a primitive type. It is an array type whose component type is reifiable. For example: int is a reifiable type (primitive type) List is a reifiable type (raw type) List<?> is a reifiable type (parameterized type with unbound wildcards) List<String> is not a reifiable type (generic type) Class<?> is...