Java 中调用方法的三种方式——静态 vs 非静态

Question

I am trying to figure out different ways to call methods, and during experimenting, I have come up with 3 ways to do something.

public static boolean isFoo(int bar) {
    return bar % 2 == 0;
}

//in a driver class:
foo.isFoo(7);

or

public static int foo;

public Foo(int foo) {
    this.foo = foo;

public boolean isFoo() {
    return foo % 2 == 0;
}

//in a driver class:
Foo foo = new Foo(4);
System.out.println(foo.isFoo());

or

public static int foo;

public Foo(int foo) {
    this.foo = foo;
}

public static int getFoo() {
    return foo;
}

public static boolean isFoo(Foo foo) {
    return foo.getFoo() % 2 == 0;
}


//in a driver class:
Foo foo = new Foo(14);
System.out.println(Foo.isFoo(foo));

Which of these 3 ways are considered static and why? I'm not sure because they all use the word static, thus I believe that in the driver, I would be referring to all of them in a static context. Are they all static?

I have attempted googling but none seem to connect to my situation.

Thanks for your help.

Answer 1

You have only 2 static methods, first and third. Second one is instance method.

Coming to your actual question, do not over think. Keep the most clean and readable way. Perfect static method I would say here is

public static boolean isFoo(int bar) {
    return bar % 2 == 0;
}