Check if a given integer is power of two
Code organization

There is nothing in the description and the posted code to justify storing the result of the "is power of 2" calculation in a class.
It would be better to simply return it.
The code is also simple enough that you could collapse the if-else chain to a single line:

public static boolean isPowerOfTwo(int num) {
    return num &gt; 0 &amp;&amp; (num &amp; (num - 1)) == 0;
}


Testing

I suggest to look into proper unit testing methods,
for example JUnit4 which comes bundled in most IDEs.
The tests you wrote in main would look like this using JUnit4:

private boolean isPowerOfTwo(int num) {
    return Solution.isPowerOfTwo(num);
}

@Test
public void minus1_should_not_be_power_of_2() {
    assertFalse(isPowerOfTwo(-1));
}

@Test
public void zero_should_not_be_power_of_2() {
    assertFalse(isPowerOfTwo(0));
}

// ... and so on