Java ADT——一元二次多項式

1、一元二次多項式抽象データ型類QUAdratic.java

package com.practice1_2;

/**
 *        ADT 
 */
public class QUAdratic {
    private int a;
    private int b;
    private int c;

    public QUAdratic(){
        this.a = 0;
        this.b = 0;
        this.c = 0;
    }

    public QUAdratic(int a, int b, int c){
        this.a = a;
        this.b = b;
        this.c = c;
    }

    public int getA() {
        return a;
    }

    public int getB() {
        return b;
    }

    public int getC() {
        return c;
    }

    public void setA(int a) {
        this.a = a;
    }

    public void setB(int b) {
        this.b = b;
    }

    public void setC(int c) {
        this.c = c;
    }
}

 
2、一元二次多項式操作インタフェースQUAbstratic.java

package com.practice1_2;

/**
 *            
 */
public interface QUAbstratic {
    //            
    QUAdratic InitQuadreatic(int a, int b, int c);
    //       ，         
    QUAdratic Add(QUAdratic q1, QUAdratic q2);
    //          x ，       
    int Eval(QUAdratic q, int x);
    //       0 ，    
    float[] Root(QUAdratic q);
    //     
    void Print(QUAdratic q);
}

 
3、一元二次多項式ADTとインタフェースを応用し、相応の機能を実現する

package com.practice1_2;


/**
 *          ADT        
 * 1、     x  ，       
 * 2、         
 */
public class QUAbtraticAppli implements QUAbstratic{

    public static void main(String[] args){
        QUAbtraticAppli app = new QUAbtraticAppli();
        app.test();
    }

    private void test(){
        QUAdratic q1 = InitQuadreatic(1,4,3);
        QUAdratic q2 = InitQuadreatic(-2,5,-8);
        QUAdratic total = Add(q1,q2);
        Print(q1);
        Print(q2);
        Print(total);
        System.out.println("x 2     ：" + Eval(total, 2));
        judgeRoot(total);
    }

    private void judgeRoot(QUAdratic q){
        float[] result = Root(q);
        if(result[0] == -1){
            System.out.println("     ");
            return;
        }
        if(result[1] == 0){
            System.out.println("       : " + result[1]);
            return;
        }
        System.out.println("       : ");
        System.out.println("    ：x1 = " + result[1]);
        System.out.println("    : x2 = " + result[2]);
    }

    @Override
    public QUAdratic InitQuadreatic(int a, int b, int c) {
        return new QUAdratic(a,b,c);
    }

    @Override
    public QUAdratic Add(QUAdratic q1, QUAdratic q2) {
        QUAdratic total = new QUAdratic();
        total.setA(q1.getA() + q2.getA());
        total.setB(q1.getB() + q2.getB());
        total.setC(q1.getC() + q2.getC());
        return total;
    }

    @Override
    public int Eval(QUAdratic q, int x) {
        return q.getA() * (int)Math.pow(x,2) + q.getB() * x + q.getC();
    }

    @Override
    public float[] Root(QUAdratic q) {
        float[] result = new float[3];
        float derta = (float)Math.pow(q.getB(),2) - 4*q.getA()*q.getC();
        if(derta < 0){
            result[0] = -1;
            result[1] = 0;
            result[2] = 0;
            return result;
        }
        else if(derta == 0){
            result[0] = 0;
            result[1] = -1 * q.getB() / (2 * q.getA());
            result[2] = 0;
            return result;
        }
        else {
            result[0] = 1;
            result[1] = (-1 * q.getB() + (float)Math.sqrt(derta)) / (2 * q.getA());
            result[2] = (-1 * q.getB() - (float)Math.sqrt(derta)) / (2 * q.getA());
            return result;
        }
    }

    @Override
    public void Print(QUAdratic q) {
        if(q.getA() != 0){
            if(q.getA() != -1 && q.getA() != 1)
                System.out.print(q.getA() + "x^2");
            else {
                if(q.getA() == 1)
                    System.out.print("x^2");
                else
                    System.out.print("-x^2");
            }
        }
        if(q.getB() != 0){
            if(q.getB() >0) {
                if(q.getB() != 1)
                    System.out.print("+" + q.getB() + "x");
                else
                    System.out.print("+x");
            }
            else {
                if(q.getB() != -1)
                    System.out.print(q.getB() + "x");
                else
                    System.out.print("-x");
            }
        }
        if(q.getC() != 0){
            if(q.getC() >0)
                System.out.print("+" + q.getC());
            else
                System.out.print(q.getC());
        }
        System.out.println();
    }
}

 
4、運行結果:

x^2+4x+3
-2x^2+5x-8
-x^2+9x-5
x 2     ：9
       : 
    ：x1 = 0.5948751
    : x2 = 8.405125

Process finished with exit code 0