如何将一个整型变量从一个JFrame共享到另一个？

public class SharedData {
    private int sharedVariable;

    public int getSharedVariable() {
        return sharedVariable;
    }

    public void setSharedVariable(int value) {
        sharedVariable = value;
    }
}

SharedData sharedData = new SharedData();
sharedData.setSharedVariable(10);

SharedData sharedData = firstFrame.getSharedData();
int sharedVariable = sharedData.getSharedVariable();