Question

i have an array with some double value inside:

private double speed[] = {50, 80, 120, 70.3};

public void printSpeed() {
    for(int i = 0; i<=speed.length-1; i++ ) {
        System.out.println(speed[i]);
    }
}

output 
50.0
80.0
12.0
70.3

wanted output
50
80
12
70.3

How to do print the exactly string of the array?

Answer 1

One thing to note to start with: the final value will not be exactly 70.3, as that can’t be exactly represented in a double. If exact decimal values are important to you, you should consider using BigDecimal instead.

It sounds like you want a NumberFormat which omits trailing insignificant digits:

import java.text.*;

public class Test {

    public static void main(String[] args) {
        // Consider specifying the locale here too
        NumberFormat nf = new DecimalFormat("0.#");

        double[] speeds = { 50, 80, 120, 70.3 };
        for (double speed : speeds) {
            System.out.println(nf.format(speed));
        }
    }

}

(As an aside, I would strongly advise you to keep the [] for array declarations with the type information – double[] speeds instead of double speeds[]. It’s much more idiomatic Java, and it puts all the type information in one place.)