小编Bri*_*nry的帖子

我正在做一个项目,这部分程序不起作用.它要求输入一个字符,然后它读取给定的文本文件,并输出文本文件中出现的那个字母的百分比.这是代码:

public static void inputLetterFrequency() {
    String letterInput = JOptionPane.showInputDialog("Please input a letter to find out the frequency");
    letterInput.toUpperCase();
    char c = letterInput.charAt(0);
    content = content.toUpperCase();

    for (int i = 0; i < content.length(); i++) {
        if (content.charAt(i) == c) {
            letterOccurence++;
        }
    }

    letterFrequency = (letterOccurence / numberCharacters) * 100.0;

    JOptionPane.showMessageDialog(null, "Frequency of letter " + c + " is " + letterFrequency + "%");
    String tryAgain = JOptionPane.showInputDialog("Please choose an option: \n1 to input another letter \n2 to …

我正在尝试一些代码,但我无法编译它.有什么错误吗？我已附上以下代码.

import java.util.*;
import java.io.*;
import javax.swing.*;
import java.awt.event.*;

public class Node
{
  private int nodeId;
  private List<Connection> outboundConnections = new ArrayList<>();

  public Node(int nodeId)
  {
    this.nodeId = nodeId;
  }

  public void addConnection(Connection connection)
  {
    this.outboundConnections.add(connection);
  }
}

当我编译时,我遇到了这种错误:

Node.java:9: error: cannot find symbol

  private List<Connection> outboundConnections = new ArrayList<>();

               ^
  symbol:   class Connection

  location: class Node

Node.java:16: error: cannot find symbol

  public void addConnection(Connection connection)
                            ^
  symbol:   class Connection

  location: class Node

Node.java:9: error: unexpected type

  private List<Connection> outboundConnections …