How can I know if Object is String type object?

Question

I have to know if Object is String or any other class type, how can I do it? Currently I do it like below, but its not very good coding.

try {
          


        

Answer 1

From JDK 14+ which includes JEP 305 we can do Pattern Matching for instanceof

Patterns basically test that a value has a certain type, and can extract information from the value when it has the matching type.

Before Java 14

if (obj instanceof String) {
    String str = (String) obj; // need to declare and cast again the object
    .. str.contains(..) ..
}else{
     str = ....
}

Java 14 enhancements

if (!(obj instanceof String str)) {
    .. str.contains(..) .. // no need to declare str object again with casting
} else {
    .. str....
}

We can also combine the type check and other conditions together

if (obj instanceof String str && str.length() > 4) {.. str.contains(..) ..}

The use of pattern matching in instanceof should reduce the overall number of explicit casts in Java programs.

PS: instanceOf will only match when the object is not null, then only it can be assigned to str.

Answer 2

Guard your cast with instanceof

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

Answer 3

Use the instanceof syntax.

Like so:

Object foo = "";

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

Answer 4

Its possible you don't need to know depending on what you are doing with it.

String myString = object.toString();

or if object can be null

String myString = String.valueOf(object);

Answer 5

 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

Answer 6

Either use instanceof or method Class.isAssignableFrom(Class<?> cls).