int : primitive type
Integer : The {@Code Integer} class wraps a value of the primitive type {@code int}
package com.local.test;
/**
- Hello world!
*/ public class App { public static void main( String[] args ) { System.out.println( "Hello World!" );
// int testInt = null; // System.out.println( "testInt : " + testInt ); /*Exception in thread "main" java.lang.Error: Unresolved compilation problem: Type mismatch: cannot convert from null to int */ Integer testInteger = null; System.out.println( "testInteger : " + testInteger );
Integer numInteger = 20; System.out.println( "numInteger : " + numInteger ); int numInt = numInteger; System.out.println( "numInt : " + numInt ); } }