有人知道为什么当我打印最后一条消息（“report header..etc etc”）时，列表上的计数会更新，但我只打印最后一个人的输入值？
另外，我怎样才能这样做，只有当这个人有30个或更多学分或者少于90个学分时，他们的名字和学分才会被存储在数组中，否则对输入什么都不做？
最后，在“管理员审核”提示部分中，如果我输入与输入匹配的名称，它应该删除该名称，但在我当前的代码中，它只会将名称替换为我输入的名称..
final int MAX_ON_LIST = 50;
String[] stuName = new String[1];
int[] numCredits = new int[1];
int currentSize = 0;
String question = JOptionPane.showInputDialog("Are you done entering students? (Enter 'Y' or 'N')");
while (question.equalsIgnoreCase("n")) {
for (int i = 0; i < stuName.length; i++) {
do {
try {
stuName[i] = JOptionPane.showInputDialog("Enter student name:");
currentSize++;
}
catch (NumberFormatException e) {
stuName[i] = "";
}
if (stuName[i].equals("")) {
JOptionPane.showMessageDialog(null, "Name cannot be blank");
}
} while (stuName[i].equals(""));
}
for (int i = 0; i < numCredits.length; i++) {
do {
try {
numCredits[i] = Integer.parseInt(JOptionPane.showInputDialog("Enter # of completed credits:"));
}
catch (NumberFormatException e) {
numCredits[i] = -1;
}
if (numCredits[i] < 0) {
JOptionPane.showMessageDialog(null, "# of credits can't be less than 0");
}
} while (numCredits[i] < 0);
}
JOptionPane.showMessageDialog(null, Arrays.toString(stuName) + "\n" + Arrays.toString(numCredits));
question = JOptionPane.showInputDialog("Are you done entering students? (Enter 'Y' or 'N')");
}
String nxtQuestion = JOptionPane.showInputDialog("Are you done with the admin. review? (Enter 'Y' or 'N')");
while (nxtQuestion.equalsIgnoreCase("n")) {
String searchValue = JOptionPane.showInputDialog("Enter a name:");;
int position = 0;
boolean found = false;
while (position < stuName.length && !found) {
if (stuName[position].equalsIgnoreCase(searchValue)) {
found = true;
}
else {
++position;
}
}
if (found) {
stuName[1] = stuName[currentSize - 1];
--currentSize;
JOptionPane.showMessageDialog(null, Arrays.toString(stuName) + "\n" + Arrays.toString(numCredits));
}
else {
JOptionPane.showMessageDialog(null, "Name not on list");
JOptionPane.showMessageDialog(null, Arrays.toString(stuName) + "\n" + Arrays.toString(numCredits));
}
nxtQuestion = JOptionPane.showInputDialog("Are you done with the admin. review? (Enter 'Y' or 'N')");
}
if (nxtQuestion.equalsIgnoreCase("y"));
{
JOptionPane.showMessageDialog(null,
"Report Header\n\n" + "# of student's on list: " + currentSize + "\nNames: " + Arrays.toString(stuName) +
"\nCredits: " + Arrays.toString(numCredits));
}
答案 0 :(得分：1)
每个数组都有一个元素。每次添加名称时，都会将其放入数组中的相同位置。
String[] stuName = new String[1];
int[] numCredits = new int[1];
此循环始终只有一次传递，i = 0。
for (int i = 0; i < stuName.length; i++) {
替代方案包括：
java.util.List名学生，每次调用List.add（）时都会根据需要增长。java.util.Map名学生。答案 1 :(得分：1)
我不确定你为什么要经历使用数组的所有痛苦，而List（ArrayList或LinkedList）更适合你的需求。我假设这是某种必须使用数组的任务。否则，应该重写整个代码。
如上所述，数组不会改变大小 - 两个数组的大小始终都是1。如果您输入多个学生，那么这也会导致索引越界异常，然后在管理员中输入最后一个学生的姓名。
最后一个学生的名字是唯一保存的名字，这就是为什么它是唯一打印的名字。
为了只存储信用卡＆gt; = 30和＆lt; = 90的人，您可以使用简单的if。
另请注意程序最后部分的代码：
if (nxtQuestion.equalsIgnoreCase("y"));
{
// Do something
}
如果if无效则由于分号。 花括号中的部分（我在其中放置“做某事”注释）将始终执行，它与if分开。 （Java允许您将代码块放在花括号中以限制局部变量的范围。）
P.S。这是一个稍好的版本（至少它可以工作）：
public static void main(String[] args) {
final int MAX_ON_LIST = 50;
final int bottomCreditsLimit = 30;
final int topCreditsLimit = 90;
String[] stuName = new String[0];
int[] numCredits = new int[0];
String question = JOptionPane.showInputDialog("Are you done entering students? (Enter 'Y' or 'N')");
while (question.equalsIgnoreCase("n") && stuName.length < MAX_ON_LIST) {
String stuNameInput = "";
do {
stuNameInput = JOptionPane.showInputDialog("Enter student name:").trim();
if (stuNameInput.equals("")) {
JOptionPane.showMessageDialog(null, "Name cannot be blank");
}
} while (stuNameInput.equals(""));
int numCreditsInput = -1;
do {
try {
numCreditsInput = Integer.parseInt(JOptionPane.showInputDialog("Enter # of completed credits:").trim());
if (numCreditsInput < 0) {
JOptionPane.showMessageDialog(null, "# of credits can't be less than 0");
}
} catch (NumberFormatException e) {
JOptionPane.showMessageDialog(null, "Please input integer value");
}
} while (numCreditsInput < 0);
if (numCreditsInput >= bottomCreditsLimit && numCreditsInput <= topCreditsLimit) {
stuName = Arrays.copyOf(stuName, stuName.length + 1);
stuName[stuName.length - 1] = stuNameInput;
numCredits = Arrays.copyOf(numCredits, numCredits.length + 1);
numCredits[numCredits.length - 1] = numCreditsInput;
JOptionPane.showMessageDialog(null, Arrays.toString(stuName) + "\n" + Arrays.toString(numCredits));
}
question = JOptionPane.showInputDialog("Are you done entering students? (Enter 'Y' or 'N')");
}
String nxtQuestion = JOptionPane.showInputDialog("Are you done with the admin. review? (Enter 'Y' or 'N')");
while (nxtQuestion.equalsIgnoreCase("n")) {
String searchValue = JOptionPane.showInputDialog("Enter a name:").trim();
int position = -1;
for (int i = 0; i < stuName.length; i++) {
if (stuName[i].equalsIgnoreCase(searchValue)) {
position = i;
break;
}
}
if (position >= 0) {
stuName[position] = stuName[stuName.length - 1];
stuName = Arrays.copyOf(stuName, stuName.length - 1);
numCredits[position] = numCredits[numCredits.length - 1];
numCredits = Arrays.copyOf(numCredits, numCredits.length - 1);
} else {
JOptionPane.showMessageDialog(null, "Name not on list");
}
JOptionPane.showMessageDialog(null, Arrays.toString(stuName) + "\n" + Arrays.toString(numCredits));
nxtQuestion = JOptionPane.showInputDialog("Are you done with the admin. review? (Enter 'Y' or 'N')");
}
JOptionPane.showMessageDialog(null, "Report Header\n\n" + "# of student's on list: " + stuName.length + "\nNames: " + Arrays.toString(stuName)
+ "\nCredits: " + Arrays.toString(numCredits));
}
答案 2 :(得分：0)
for循环预编译，所以你需要在使用循环之前将stuName设置为某个东西。