How to call a method when its parameter is an array?

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2

I’m new to java and I’m having some difficulties in calling a method, well, I have the following:

class main {
    public static void main(String[] args) {
        vetorFloat(vetor[x]);
    }
    private float vetorFloat(float[] vetor) {
        //algum código
        return vetor[x];
    }
}

The method vetorFloat is in the same class as the main method main.

How could I call this method?

java

2 answers

2


Thus:

float[] floatArray = new float[]{1.0f, 2.2f, 3.4f};
vetorFloat(floatArray);

Then the method and class in static context would look like this:

class main {
    public static void main(String[] args) {
        float[] floatArray = new float[]{1.0f, 2.2f, 3.4f};
        vetorFloat(floatArray );
    }
    private static float vetorFloat(float[] vetor) {
        //algum código
        return vetor[x];
    }
}

Only that one X in the return vetor[x]; will give build problem. It needs to be solved. It can be like this:

class Main {
    public static void main(String[] args) {
        float[] floatArray = new float[]{1.0f, 2.2f, 3.4f};
        vetorFloat(floatArray );
    }
    private static float vetorFloat(float[] vetor) {
        int x = 0;
        return vetor[x];
    }
}

Now your method will return the first position of the past array.

As you did, you are passing an element of the array, not the whole array. In my example, I declare a new array and already fill it. Hence the variable floatArray represents the whole array and if I do floatArray[0], i am accessing only the first element of the array, which in this case is 1.0.

That "F" right there in the number, it’s for Java to know that it’s a float. When you fill in an arbitrary number in the code, java doesn’t know if it treats as int, float, long... then you specify after declaring the number. Examples:

  • long 0L
  • float 0.0f
  • double 0.0d

See the official documentation on the primitive types. It can help a lot.

  • 1

    Complementing: call the method vetorFloat() in a static context also gives build error. One must declare the method vetorFloat() as static or call it in instance context (a non-static method, for example).

  • @Piovezan, I noticed this. I used Ricardo Giaviti’s answer and gave such error in the compilation... "non-static method vetorFloat(float[]) cannot be referenced from a Static context".

  • Sorry guys. I didn’t notice. I edited my answer.

  • I stopped to analyze the situation and I realized something... I don’t need all this, because everything is within the method vetorFloat(float[] vetor), When I say everything, I mean data entry, data output, accounts, data processing and so on, what I meant is something that just tells the program: run this method. In this case, the main method main would just be a method that executes other methods, nothing more.

2

In his method main() you make three mistakes:

  1. Uses undeclared variables: vetor and x
  2. Passes a argument of the type float for a method that has a vector of floats as a parameter (float[] is a vector of floats)
  3. You call a non-static method (vetorFloat()) from a static method (main()).

You also do other things that are not mistakes but should warn you:

  1. According to the convention used in Java, classes must start with a capital letter.
  2. You are not using the return method vetorFloat() for nothing (this probably you had already noticed, but I could not help but quote).

Fixing

This is just my suggestion, it fixes the mistakes and the warning I quoted above:

class Main {
    public static void main(String[] args) {
        float[] vetor = {1, 2, 5};
        System.out.println(vetorFloat(vetor));
    }
    private static float vetorFloat(float[] vetor) {
         return vetor[vetor.length-1]; //retorna o último elemento do vetor
    }
}

Note: don’t forget to rename your file to Main.java

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