Java中的ArrayList仅打印列表中的最后一个对象

Question

I'm taking an online Computer Science Course for school and I have hit a bump in the road that after two days I still can not figure out, I have turned to the community.

I have written a piece of code that I need to print the catapult distances. I have put these objects in an ArrayList and have developed a class file for the catapult instance. I want my code to print a list of the distances and the MPH at the start of the row (You can see this with the source files below with an example of what I want it to look like). Here is the code I have developed up to this point:

Catapult.java

public class Catapult {
    static double speed, angle, MPS, Rad, R;

Catapult(double launchSpeed, double launchAngle) {
    angle = launchAngle;
    speed = launchSpeed;

public void convMPHtoMPS() {
    MPS = speed * 0.44704;
}

public void convDegToRad() {
    Rad = Math.toRadians(angle);
}

public void calcDistance() {
    R = (Math.pow(MPS, 2)*Math.sin(2*Rad))/(Math.pow(9.8, 2));
}

public void convMtoFt() {
    R = R * 3.28084;
}

public double getMPH() {
    return speed;
}

public double getAngle() {
    return angle;
}

public double getMetersPerSecond() {
    return MPS;
}

public double getRadians() {
    return Rad;
}

public double getDistance() {
    return R;
}
}

CatapultTester.java

    public static void calcData() {
        int mph = 25;
        for (int i = 0; i < 7; i++) {
            int deg = 25;
            for (int j = 0; j < 6; j++) {
                CP.add(new Catapult(mph, deg));
                //System.out.println(mph);
                //System.out.println(deg);
                deg += 5;   
            }
            mph += 5;
        }
        System.out.println(CP.size());
        Catapult data;
        for (int index = 0; index < CP.size(); index++) {
            data = CP.get(index);
            data.convMPHtoMPS();
            data.convDegToRad();
            data.calcDistance();
            data.convMtoFt();
            //System.out.println(data.getMPH());
            //System.out.println(data.getDistance());
        }
        presentData();
    }
    public static void presentData() {
        Catapult data;
        for (int index = 0; index < CP.size(); index++) {
            data = CP.get(index);
            System.out.printf("%1f", data.getMPH());
            for (int j = 0; j < 6; j++) {
                System.out.printf("%4.2f", data.getDistance());
            }
        }
    }

Expected Output

MPH    25 deg    30 deg    35 deg    40 deg     45 deg    50 deg
25     distance  distance  distance  distance   distance  distance
30     distance  distance  distance  distance   distance  distance
...

Distance is the formula declared in Catapult.java

R = (Math.pow(MPS, 2)*Math.sin(2*Rad))/Math.pow(9.8)/2));

Actual Output:

MPH    25 deg    30 deg    35 deg    40 deg     45 deg    50 deg
55     20.34     20.34     20.34     20.34      20.34     20.34
55     20.34     20.34     20.34     20.34      20.34     20.34
55     20.34     20.34     20.34     20.34      20.34     20.34
...

Thank you all for your help and I apologize for any grammatical errors or confusion with code. I am new to the Java programming language!

Answer 1

您不应该在您的情况下使用静态变量，因为它将在该类的所有对象（弹射器）中通用