Java 如果找不到项目并显示适当的消息，我应该在何处写入？ public static void modifyBall（String[]hookPotentialArray，String[]namebarray，int[]ballweightary，int count）{ 扫描仪键盘=新扫描仪（System.in）； System.out.println（“请输入要修改的球的名称：”）； 字符串名称=keyboard.nextLine（）； for（int i=0；i

您可以创建一个布尔值，并在if语句中将其设置为true，这表示已找到该值。您可以在循环后检查布尔值是否为true，如果为true，则显示错误消息

例如：

public static void modifyBall(String[] hookPotentialArray, String[] nameBallArray, int[] ballWeightArray, int count) {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Please enter the name of the ball you would like to modify: ");
        String name = keyboard.nextLine();

        for (int i = 0; i < count; i++) {
            if (name.compareToIgnoreCase(nameBallArray[i]) == 0) {
                System.out.println("Please enter a new name for the ball: ");
                String ballName = keyboard.nextLine();
                System.out.println("Please enter a new weight for the ball: ");
                int ballWeight = keyboard.nextInt();
                System.out.println("Please enter a new hook potential for the ball: ");
                String hookPotential = keyboard.next();

                nameBallArray[i] = ballName;
                ballWeightArray[i] = ballWeight;
                hookPotentialArray[i] = hookPotential;

                System.out.println("The ball list has been updated.");
                System.out.println("");


            }

        }

public static void modifyBall（String[]hookPotentialArray，String[]namebarray，int[]ballweightary，int count）{
boolean found=false；//是否找到它的布尔值
扫描仪键盘=新扫描仪（System.in）；
System.out.println（“请输入要修改的球的名称：”）；
字符串名称=keyboard.nextLine（）；
for（int i=0；i

---

我还在if语句的末尾添加了一个break，以在找到项时中断循环（如果已找到项，则继续进行没有意义）。

在循环之前将标志变量设置为0。在if内部将其设置为1。在循环之后检查它是否仍然为零。然后打印相应的消息，表明未找到项

public static void modifyBall(String[] hookPotentialArray, String[] nameBallArray, int[] ballWeightArray, int count) {
boolean found = false; //boolean for if it's found or not
Scanner keyboard = new Scanner(System.in);
System.out.println("Please enter the name of the ball you would like to modify: ");
String name = keyboard.nextLine();

for (int i = 0; i < count; i++) {
    if (name.compareToIgnoreCase(nameBallArray[i]) == 0) {
        found = true; //set boolean if found
        System.out.println("Please enter a new name for the ball: ");
        String ballName = keyboard.nextLine();
        System.out.println("Please enter a new weight for the ball: ");
        int ballWeight = keyboard.nextInt();
        System.out.println("Please enter a new hook potential for the ball: ");
        String hookPotential = keyboard.next();

        nameBallArray[i] = ballName;
        ballWeightArray[i] = ballWeight;
        hookPotentialArray[i] = hookPotential;

        System.out.println("The ball list has been updated.");
        System.out.println("");
        break; //break out of loop if item found
    }
}
//check if boolean is false then print error message
if (!found)
{
    System.out.println("There was a problem finding your item.");
}

试试这个：

Boolean flag  = false; // before loop

flag = true; //inside if

// After loop
if(!flag)
    System.out.println("Not Found");

public static void modifyBall（String[]hookPotentialArray，String[]namebarray，int[]ballweightary，int count）{
扫描仪键盘=新扫描仪（System.in）；
System.out.println（“请输入要修改的球的名称：”）；
字符串名称=keyboard.nextLine（）；
for（int i=0；i

您应该重构以分离查找/未找到球（或未找到球）的循环，并对球执行任何需要执行的操作（如果未找到球，则执行错误）这有助于提高可读性，因为更多的行缩进更少，并且有助于传达您的意图，因为循环中的大多数代码无论如何只执行一次

    public static void modifyBall(String[] hookPotentialArray, String[] nameBallArray, int[] ballWeightArray, int count) {
            Scanner keyboard = new Scanner(System.in);
            System.out.println("Please enter the name of the ball you would like to modify: ");
            String name = keyboard.nextLine();

            for (int i = 0; i < count; i++) {
                if (name.compareToIgnoreCase(nameBallArray[i]) == 0) {
                    System.out.println("Please enter a new name for the ball: ");
                    String ballName = keyboard.nextLine();
                    System.out.println("Please enter a new weight for the ball: ");
                    int ballWeight = keyboard.nextInt();
                    System.out.println("Please enter a new hook potential for the ball: ");
                    String hookPotential = keyboard.next();

                    nameBallArray[i] = ballName;
                    ballWeightArray[i] = ballWeight;
                    hookPotentialArray[i] = hookPotential;

                    System.out.println("The ball list has been updated.");
                    System.out.println("");
                    return;
                }

            }

           System.out.println("ball not found");

}

int-ballIndex=-1；
for（int i=0；i=0）{
//找到-使用ballIndex做任何事情
}否则{
//未找到-显示错误
}

int ballIndex = -1;
for (int i = 0; i < count; i++) {
    if (name.compareToIgnoreCase(nameBallArray[i]) == 0) {
       ballIndex = nameBallArray[i];
       break;
    }
}
if (ballIndex >= 0) {
  // found - do everything using ballIndex
} else {
  // not found - display error
}