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DDR
Asked: 2020-03-18 10:51:13 +0800 CST 2020-03-18 10:51:13 +0800 CST

Know type of variables

  • 772

For example I have this variablevar

int var=200;

How can I know what type is a variable ( int, String, boolean...)?

Since if I print it I don't know if it's a intor a String(in this case).

java

2 Answers

  1. Another way to do it, without having to create the variable with a wrapper, would be to put Objectsomething like this at the time of obtaining the class name:

    int i = 1;
System.out.println(((Object)i).getClass().getName());

    Departure:

    java.lang.Integer

    It would work for non-primitive types as well:

    Integer mInt = 1;
System.out.println(((Object)mInt).getClass().getName());

    Departure:

    java.lang.Integer

    For more elegant or advanced use, you can implement the class FieldSpy, explained in the official Java documentation. On the tutorial page they also explain some usage examples .

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  2. Best Answer

    You can use Wrappersinstead of primitive types, for example for your case instead of intyou would use Integer.

    Integer var = 200;
System.out.println("Valor: " + var + ", Tipo de dato: " + var.getClass());

    In the output you would get the following:

    Value: 200, Data type: java.lang.Integer.

    Here is a table of primitive types and their equivalents in Wrappers:

    Clase Wrapper  Tipo Primitivo
Integer         int
Double          double
Boolean         boolean
Byte            byte
Character       char
Long            long
Short           short
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