How can I know if Object is String type object?

Guard your cast with instanceof

String myString;
if (object instanceof String) {
  myString = (String) object;
}

Use the instanceof syntax.

Like so:

Object foo = "";

if( foo instanceof String ) {
  // do something String related to foo
}

 object instanceof Type

is true if the object is a Type or a subclass of Type

 object.getClass().equals(Type.class)

is true only if the object is a Type

Related