解決二次方程使用方法，java

Question

我有一個java程序來編寫解決二次方程，但分配要求我有每個任務的方法：顯示方程，確定方程是否有真正的解決方案，計算解決方案，並顯示解決方案（如果存在）。我除了檢查解決方案是否真實，除了我的方法說它們是未定義的外，其他方法都有。有人可以幫我格式化我的方法，我不知道如何實現它們？這裏是我迄今爲止代碼：

import java.util.Scanner; 
public class QuadraticFormula { 

public static void main(String[] args) 
{ 
    //Creating scanner and variables 
    Scanner s = new Scanner(System.in); 
    System.out.println("Insert value for a: "); 
    double a = Double.parseDouble(s.nextLine()); 
    System.out.println("Insert value for b: "); 
    double b = Double.parseDouble(s.nextLine()); 
    System.out.println("Insert value for c: "); 
    double c = Double.parseDouble(s.nextLine()); 

    //Display format for negatives 
    displayEquation(double a, double b, double c);{ 
    if (b > 0 && c > 0){ 
     System.out.println(a + "x^2 + " + b + "x + " + c + " =0");} 
    if (b < 0 && c > 0){ 
     System.out.println(a + "x^2 " + b + "x + " + c + " =0");} 
    if (b > 0 && c < 0){ 
     System.out.println(a + "x^2 + " + b + "x " + c + " =0");} 
    if (b < 0 && c < 0){ 
     System.out.println(a + "x^2 " + b + "x " + c + " =0");} 
    s.close(); 
    } 
    //The work/formula 
    private static double calculateSolution(double a, double b, double c); 
    { 
    double answer1 = (-b + Math.sqrt(Math.pow(b, 2) - (4 * a * c)))/(2 * a); 
    return answer1; 
    } 

    private static double calculateSolution(double a, double b, double c); 
    { 
    double answer2 = (-b - Math.sqrt(Math.pow(b, 2) - (4 * a * c)))/(2 * a); 
    return answer2; 
    } 
    //Display results and check if the solution is imaginary (real or not) 
    private static void displaySolutions(double answer1, double answer2); { 
    if (Double.isNaN(answer1) || Double.isNaN(answer2)) 
    { 
     System.out.println("Answer contains imaginary numbers"); 
    } else System.out.println("The values are: " + answer1 + ", " + answer2); 
} 
} 

}

Answer 1

你的方法需要被你的主要方法之外定義。然後你可以用你的主要方法調用它們：

displayEquation(a, b, c); 

你也應該在你的方法定義之後去掉分號。它應該看起來像這樣：

public class QuadraticFormula { 

public static void main(String[] args) 
{ 
    //Creating scanner and variables 
    Scanner s = new Scanner(System.in); 
    System.out.println("Insert value for a: "); 
    double a = Double.parseDouble(s.nextLine()); 
    System.out.println("Insert value for b: "); 
    double b = Double.parseDouble(s.nextLine()); 
    System.out.println("Insert value for c: "); 
    double c = Double.parseDouble(s.nextLine()); 
    s.close(); 
} 
    //Display format for negatives 
    public static void displayEquation(double a, double b, double c) { 
     if (b > 0 && c > 0){ 
      System.out.println(a + "x^2 + " + b + "x + " + c + " =0");} 
     if (b < 0 && c > 0){ 
      System.out.println(a + "x^2 " + b + "x + " + c + " =0");} 
     if (b > 0 && c < 0){ 
      System.out.println(a + "x^2 + " + b + "x " + c + " =0");} 
     if (b < 0 && c < 0){ 
      System.out.println(a + "x^2 " + b + "x " + c + " =0");} 
    } 

    private static double calculateSolution(double a, double b, double c) { 
     double answer2 = (-b - Math.sqrt(Math.pow(b, 2) - (4 * a * c)))/(2 * a); 
     return answer2; 
    } 

    //Display results and check if the solution is imaginary (real or not) 
    private static void displaySolutions(double answer1, double answer2) { 
     if (Double.isNaN(answer1) || Double.isNaN(answer2)) 
     { 
      System.out.println("Answer contains imaginary numbers"); 
     } 
     else System.out.println("The values are: " + answer1 + ", " + answer2); 
    } 
}