To convert a string to an in int in java we use Integer.parseInt() function. Example: String anyNumber = "15" ; int result = Integer . parseInt ( anyNumber ) ; System . out . println ( result ) ; int aaa = Integer . parseInt ( "123456" ); See the Java Documentation for more information. (If you have it in a StringBuilder (or the ancient StringBuffer ), you'll need to do Integer.parseInt(myBuilderOrBuffer.toString()); instead). A very important point to consider is that the Integer parser throws NumberFormatException as stated in Javadoc . int aaa ; String StringThatCouldBeANumberOrNot = "2623263hiworld" ; //will throw exception String StringThatCouldBeANumberOrNot2 = "2336263" ; //will not throw exception try { aaa = Integer . parseInt ( StringThatCouldBeANumberOrNot ); } catch ( NumberFormatException e ) { //Will Throw exception! ...