关于 IF 语句

试试这个：

if (discriminant > 0 ) {
  System.out.printf("The roots are %8.6f and %8.6f ", root1, root2);
}
else if (discriminant == 0 ) {
  System.out.print("The root is  " +  root1);
}
else {
  System.out.print("There are no real roots ");
}

您的代码当前正在运行，如下所示：

// first if group
if (discriminant > 0 ) {
  System.out.printf("The roots are %8.6f and %8.6f ", root1, root2);
}
// second if group
if (discriminant == 0 ) {
  System.out.print("The root is  " +  root1);
}
// handle everything else for second if group only
else {
  System.out.print("There are no real roots ");
}

它应该按如下方式运行：

// one if group
if (discriminant > 0 ) {
  System.out.printf("The roots are %8.6f and %8.6f ", root1, root2);
}
else {
  // second if condition in else statement
  if (discriminant == 0 ) {
    System.out.print("The root is  " +  root1);
  }
  // handle everything else
  else {
    System.out.print("There are no real roots ");
  }
}

你使用两个 if 和一个其他。在这种情况下，首先检查第一个条件。然后随着下一个if.if.如果出现错误，那么控制器也会出现在其他方面。

import java.util.Scanner;
public class sha {
public static void main(String[] args ){
Scanner input = new Scanner (System.in);
System.out.println("Enter a , b , and c : ");
double a = input.nextDouble();
double b = input.nextDouble();
double c = input.nextDouble();
// the equations 
double discriminant = Math.pow (b , 2) - 4 * a * c;
double root1 = (-b + Math.sqrt(discriminant))/2 * a ;
double root2 = (-b - Math.sqrt(discriminant))/2 * a ;
if (discriminant > 0 ){
System.out.printf("The roots are %8.6f and %8.6f ", root1, root2);
}
else if (discriminant == 0 ){
System.out.print("The root is  " +  root1);
}
else  {
System.out.print("There are no real roots ");
}


}
}

你需要在代码中使用if、else if和else。然后，只有控件将只执行一个条件首先变为 true 的循环，并忽略其他else if和else循环。否则，条件测试将在所有if循环中发生，如果条件测试通过，则在循环中执行语句，无论先前的循环语句是否被执行<</p>