Question

语法错误＆＃34;;＆＃34; ,,预期在线＆＃34;双a，b，c，判别，root;＆＃34;

如何解决此错误？

public class Quadratic {

    double a, b, c, discriminant, root;

    discriminant = (b * b) - 4 * a * c;

    public Quadratic(double a, double b, double c) {
    }

    public String calculateroots() {

        if (discriminant >= 0){
            root = Math.sqrt(discriminant) / (2 * a);

            System.out.println("Your roots are " + (-1 * b) + "+" + root + "and" + (-1 * b) + (-1 * root) +".");
        }
        else {
            root = Math.sqrt(Math.abs(discriminant)) / (2 * a);

            System.out.println("Your roots are " + (-1 * b) + "+ i" + root + "and" + (-1 * b) + "i" + (-1 * root) +".");
        }
        }
    }

Answer 1

注意构造函数中的变量初始化为discriminant中的calculateroots初始化。

   public class Quadratic {

        double a, b, c, discriminant, root;

        public Quadratic(double a, double b, double c) {
            this.a = a;
            this.b = b;
            this.c = c;
        }

        public void calculateroots() {
            discriminant = (b * b) - 4 * a * c;

            if (discriminant >= 0){
                root = Math.sqrt(discriminant) / (2 * a);

                System.out.println("Your roots are " + (-1 * b) + "+" + root + "and" + (-1 * b) + (-1 * root) +".");
            }
            else {
                root = Math.sqrt(Math.abs(discriminant)) / (2 * a);

                System.out.println("Your roots are " + (-1 * b) + "+ i" + root + "and" + (-1 * b) + "i" + (-1 * root) +".");
            }

        }
    }

Answer 2

你走了。

public class Quadratic {

    double a, b, c, discriminant, root;

    public Quadratic(double a, double b, double c) {
        discriminant = (b * b) - 4 * a * c;
    }

    public void calculateroots() {

        if (discriminant >= 0) {
            root = Math.sqrt(discriminant) / (2 * a);

            System.out.println("Your roots are " + (-1 * b) + "+" + root + "and" + (-1 * b) + (-1 * root) + ".");
        } else {
            root = Math.sqrt(Math.abs(discriminant)) / (2 * a);

            System.out.println("Your roots are " + (-1 * b) + "+ i" + root + "and" + (-1 * b) + "i" + (-1 * root) + ".");
        }
    }

}

Answer 3

只回答你的问题......语法错误是由

的位置引起的

discriminant = (b * b) - 4 * a * c;

判别式被赋予(a, b ,c)未初始化的变量。

我建议将其移至calculateroots()并将返回类型更改为void：

public class Quadratic {

    double a, b, c, discriminant, root;

    public Quadratic(double a, double b, double c) {
        this.a = a; 
        this.b = b; 
        this.c = c;
    }

    public void calculateroots() {

        discriminant = (b * b) - 4 * a * c;

        if (discriminant >= 0){
            root = Math.sqrt(discriminant) / (2 * a);

            System.out.println("Your roots are " + (-1 * b) + "+" + root + "and" + (-1 * b) + (-1 * root) +".");
        }
        else {
            root = Math.sqrt(Math.abs(discriminant)) / (2 * a);

            System.out.println("Your roots are " + (-1 * b) + "+ i" + root + "and" + (-1 * b) + "i" + (-1 * root) +".");
        }
        }
    }

这样你只需创建Quadratic实例并为a，b和c的构造函数赋值，然后调用calculateroots()

错误＆＃34;;＆＃34; ,,在变量声明后预期

3 个答案: