编写一个java应用程序，该程序中有3个类：Trangle,Lader和Circle,分别用来刻画“三角形”、“梯形”和“圆形”。具体要求如下： Trangle类具有类型为double的三个边，Trangle类具有返回周长、面积以及修改三个边的方法。另外，Trangle类还具有一个boolean型的属性，该属性用来判断三个数能否构成一个三角形。 Lader类具有类型为double的上底、下底、高属性，具有返回面积的方法。 Circle类具有类型为double的半径属性，具有返回周长、面积的功能。

以下是符合要求的Java程序：

Trangle类：

public class Trangle {
    private double side1;
    private double side2;
    private double side3;
    private boolean isValid;

    public Trangle(double side1, double side2, double side3) {
        this.side1 = side1;
        this.side2 = side2;
        this.side3 = side3;

        // 判断三个数能否构成三角形
        if (side1 + side2 > side3 && side1 + side3 > side2 && side2 + side3 > side1) {
            this.isValid = true;
        } else {
            this.isValid = false;
        }
    }

    public double getSide1() {
        return side1;
    }

    public double getSide2() {
        return side2;
    }

    public double getSide3() {
        return side3;
    }

    public boolean isValid() {
        return isValid;
    }

    public void setSide1(double side1) {
        this.side1 = side1;
    }

    public void setSide2(double side2) {
        this.side2 = side2;
    }

    public void setSide3(double side3) {
        this.side3 = side3;
    }

    public double getPerimeter() {
        return side1 + side2 + side3;
    }

    public double getArea() {
        double p = getPerimeter() / 2;
        return Math.sqrt(p * (p - side1) * (p - side2) * (p - side3));
    }
}

Lader类：

public class Lader {
    private double upperBottom;
    private double lowerBottom;
    private double height;

    public Lader(double upperBottom, double lowerBottom, double height) {
        this.upperBottom = upperBottom;
        this.lowerBottom = lowerBottom;
        this.height = height;
    }

    public double getUpperBottom() {
        return upperBottom;
    }

    public double getLowerBottom() {
        return lowerBottom;
    }

    public double getHeight() {
        return height;
    }

    public double getArea() {
        return (upperBottom + lowerBottom) * height / 2;
    }
}

Circle类：

public class Circle {
    private double radius;

    public Circle(double radius) {
        this.radius = radius;
    }

    public double getRadius() {
        return radius;
    }

    public void setRadius(double radius) {
        this.radius = radius;
    }

    public double getPerimeter() {
        return 2 * Math.PI * radius;
    }

    public double getArea() {
        return Math.PI * radius * radius;
    }
}

可以在主函数中进行测试：

public static void main(String[] args) {
    // 测试Trangle类
    Trangle trangle = new Trangle(3, 4, 5);
    System.out.println("Trangle perimeter: " + trangle.getPerimeter());
    System.out.println("Trangle area: " + trangle.getArea());

    // 修改边长
    trangle.setSide1(5);
    System.out.println("Trangle perimeter: " + trangle.getPerimeter());
    System.out.println("Trangle area: " + trangle.getArea());

    // 测试Lader类
    Lader lader = new Lader(3, 5, 4);
    System.out.println("Lader area: " + lader.getArea());

    // 测试Circle类
    Circle circle = new Circle(2);
    System.out.println("Circle perimeter: " + circle.getPerimeter());
    System.out.println("Circle area: " + circle.getArea());
}