How to identify object types in java

Question

Possible Duplicate    How to determine an object  39 s class  in Java     Java determine which class an object is       I have following sample incomplete method to compare the object type of a given object  public void test Object value             if  value getClass      Integer                System out println  This is an Integer             else if value getClass      String               System out println  This is a String             else if value getClass      Float               System out println  This is a Float                   The method can be called as    test  Test    test 12   test 10 5f     this method is not actually working  please help me to make it work

User · Answer

You can compare class tokens to each other, so you could use value.getClass() == Integer.class. However, the simpler and more canonical way is to use instanceof :

    if (value instanceof Integer) {
        System.out.println("This is an Integer");
    } else if(value instanceof String) {
        System.out.println("This is a String");
    } else if(value instanceof Float) {
        System.out.println("This is a Float");
    }

Notes:

the only difference between the two is that comparing class tokens detects exact matches only, while instanceof C matches for subclasses of C too. However, in this case all the classes listed are final, so they have no subclasses. Thus instanceof is probably fine here.
as JB Nizet stated, such checks are not OO design. You may be able to solve this problem in a more OO way, e.g.
```
System.out.println("This is a(n) " + value.getClass().getSimpleName());
```

User · Answer

Use value instanceof YourClass

User · Answer

You want instanceof   if  value instanceof Integer    This will be true even for subclasses  which is usually what you want  and it is also null-safe  If you really need the exact same class  you could do  if  value getClass      Integer class    or   if  Integer class equals value getClass

User · Answer

You forgot the  class   if  value getClass      Integer class        System out println  This is an Integer       else if  value getClass      String class        System out println  This is a String      else if  value getClass      Float class        System out println  This is a Float        Note that this kind of code is usually the sign of a poor OO design   Also note that comparing the class of an object with a class and using instanceof is not the same thing  For example    foo  getClass      Object class   is false  whereas   foo  instanceof Object   is true   Whether one or the other must be used depends on your requirements

[java] How to identify object types in java

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