创建一个三角形类，成员变量三边，方法求周长，创建类主类A来测试它。

public class zhouchang {
     private double a;
     private double b;
     private double c;
    public double getA() {
        return a;
    }
    public void setA(double a) {
        this.a = a;
    }
    public double getB() {
        return b;
    }
    public void setB(double b) {
        this.b = b;
    }
    public double getC() {
        return c;
    }
    public void setC(double c) {
        this.c = c;
    }
     
public double getZhouchang()
    {
        return a+b+c;
    }
 
}

public class Test07 {

    public static void main(String[] args) {
        zhouchang sjx=new zhouchang();
        sjx.setA(11);
        sjx.setB(12);
        sjx.setC(13);
        System.out.println("三边a=11,b=12,c=13的周长是："+sjx.getZhouchang());

    }

}