Boolean wrapper class

■ You cannot instantiate Boolean objects without a new. i.e.

Boolean B = new Boolean("true"); works.

Boolean B = true; will not compile.

■ You cannot test for true or false in a Boolean using ==. You must use the booleanValue( ) method. i.e.

if ( B == true ) will not compile.

if ( B.booleanValue( ) ) works.

■ You cannot assign primitive booleans to be null. i.e.

boolean b = null; will not compile.

■ Booleans can be null, because they’re objects. Boolean null always tests false. i.e.

Boolean B = new Boolean( null );

if ( B.booleanValue( ) ) returns false.

Boolean B = null;

if( B.booleanValue( ) ) will compile but will throw a runtime NullPointerException.

■ Boolean constructors will take as true any cases of the letters in "true". (Meaning Boolean's true is case-insensitive, but its false is not). Providing anything other than various cases of the four letters t-r-u-e generates a value of false. i.e.

Boolean B = new Boolean("tRuE"); generates true.

Boolean B = new Boolean("TrUE"); generates true.

Boolean B = new Boolean("NotTrue"); generates false.

Boolean B = new Boolean("tru"); generates false.