我需要一些帮助。我正在尝试缩短我的main（）并将一些代码移到方法中并将其放在我的其他类Contact.java中。就像阅读文件这样的某些内容我想要一个只用于读取文件并将其放在Contact.java中的方法。写入文件也是如此，我想要一个单独的方法，我可以在main（）中回调。我理解如何制作该方法，但是如何将该方法从Contact.java调用回ContactList.java？有什么建议？
import java.io.*;
import java.util.*;
public class ContactList {
public static void main(String args[]) throws IOException {
Contact contact;
contact = new Contact();
int action = 0;
ArrayList<Contact> contacts = new ArrayList<Contact>();
while (action != 6) {
System.out.println("\nWelcome to Contact List DB. "
+ "What would you like to do? \n");
System.out.println("1. Enter a new person" + "\n"
+ "2. Print the contact list" + "\n"
+ "3. Retrieve a person's information by last name" + "\n"
+ "4. Retrieve a person's information by email address" + "\n"
+ "5. Retrieve all people who live in a given zip code" + "\n"
+ "6. Exit");
Scanner reader = new Scanner(System.in);
reader.useDelimiter("\n");
action = reader.nextInt();
if (action <= 0 || action > 6) {
System.out.println("Invalid selection. ");
}
switch (action) {
case 1: {
System.out.println("\nEnter Contact Last Name:");
String lastname = reader.next();
if (lastname == null) {
System.out.println("\nInvalid entry. ");
break;
}
else {
contact.setLastName(lastname.toLowerCase());
}
System.out.println("Enter Contact First Name: ");
String firstname = reader.next();
contact.setFirstName(firstname.toLowerCase());
System.out.println("Enter Contact Street Address: ");
String address = reader.next();
contact.setHouseAddress(address.toLowerCase());
System.out.println("Enter Contact City: ");
String city = reader.next();
contact.setCity(city.toLowerCase());
System.out.println("Enter Contact Zip Code: ");
String zip = reader.next();
contact.setZip(zip.toLowerCase());
System.out.println("Enter Contact Email: ");
String email = reader.next();
contact.setEmail(email.toLowerCase());
System.out.println("Enter Contact Phone Number: ");
String phone = reader.next();
contact.setPhone(phone.toLowerCase());
System.out.println("Enter Contact Notes: ");
String notes = reader.next();
contact.setNotes(notes.toLowerCase());
contacts.add(contact);
try {
Contact c = contact;
File file = new File("contactlist.csv");
// If file doesn't exists, then create it.
if (!file.exists()) {
file.createNewFile();
}
try (PrintWriter output = new PrintWriter(new FileWriter(
"contactlist.csv", true))) {
output.printf("%s\r\n", c);
} catch (Exception e) {
}
System.out.println("Your contact has been saved.");
}
catch (IOException e) {
e.printStackTrace();
}
}
break;
case 2: {
int counter = 0;
String line = null;
// Location of file to read
File file = new File("contactlist.csv");
// Sort contacts and print to console
try {
Scanner scanner = new Scanner(file);
// Before printing, add each line to a sorted set. by Seth
// Copeland
Set<String> lines = new TreeSet<>();
while (scanner.hasNextLine()) {
line = scanner.nextLine();
lines.add(line);
counter++;
}
// Print sorted contacts to console.
for (String fileLine : lines) {
String outlook = fileLine.substring(0, 1).toUpperCase()
+ fileLine.substring(1);
System.out.println(outlook);
}
scanner.close();
} catch (FileNotFoundException e) {
}
System.out.println("\n" + counter + " contacts in records.");
}
break;
case 3:
try {
System.out.println("\nEnter the last"
+ "name to search for: ");
String searchterm = reader.next();
// Open the file as a buffered reader
BufferedReader bf = new BufferedReader(new FileReader(
"contactlist.csv"));
// Start a line count and declare a string to hold our
// current line.
int linecount = 0;
String line;
// Let the user know what we are searching for
System.out.println("Searching for " + searchterm
+ " in file...");
// Loop through each line, putting the line into our line
// variable.
boolean noMatches = true;
while ((line = bf.readLine()) != null) {
// Increment the count and find the index of the word.
linecount++;
int indexfound = line.indexOf(searchterm.toLowerCase());
// If greater than -1, means we found a match.
if (indexfound > -1) {
System.out.println("\nContact was FOUND\n"
+ "\nContact " + linecount + ": " + line);
noMatches = false;
}
}
// Close the file after done searching
bf.close();
if (noMatches) {
System.out.println("\nNO MATCH FOUND.\n");
}
}
catch (IOException e) {
System.out.println("IO Error Occurred: " + e.toString());
}
break;
case 4:
try {
System.out.println("\nEnter the email "
+ "address to search for: ");
String searchterm = reader.next();
// Open the file as a buffered reader
BufferedReader bf = new BufferedReader(new FileReader(
"contactlist.csv"));
// Start a line count and declare a string to hold our
// current line.
int linecount = 0;
String line;
// Let the user know what we are searching for
System.out.println("\nSearching for " + searchterm
+ " in file...");
// Loop through each line, put the line into our line
// variable.
boolean noMatches = true;
while ((line = bf.readLine()) != null) {
// Increment the count and find the index of the word
linecount++;
int indexfound = line.indexOf(searchterm.toLowerCase());
// If greater than -1, means we found a match
if (indexfound > -1) {
System.out.println("\nContact was FOUND\n"
+ "\nContact " + linecount + ": " + line);
noMatches = false;
}
}
// Close the file after done searching
bf.close();
if (noMatches) {
System.out.println("\nNO MATCH FOUND.\n");
}
}
catch (IOException e) {
System.out.println("IO Error Occurred: " + e.toString());
}
break;
case 5:
try {
System.out.println("\nEnter the Zipcode to search for: ");
String searchterm = reader.next();
// Open the file as a buffered reader
BufferedReader bf = new BufferedReader(new FileReader(
"contactlist.csv"));
// Start a line count and declare a string to hold our
// current line.
int linecount = 0;
String line;
// Let the user know what we are searching for
System.out.println("\nSearching for " + searchterm
+ " in file...");
// Loop through each line, stashing the line into our line
// variable.
boolean noMatches = true;
while ((line = bf.readLine()) != null) {
// Increment the count and find the index of the word.
linecount++;
int indexfound = line.indexOf(searchterm.toLowerCase());
// If greater than -1, means we found a match.
if (indexfound > -1) {
System.out.println("\nContact was FOUND\n"
+ "\nContact " + linecount + ": " + line);
noMatches = false;
}
}
// Close the file after done searching
bf.close();
if (noMatches) {
System.out.println("\nNO MATCH FOUND.\n");
}
}
catch (IOException e) {
System.out.println("IO Error Occurred: " + e.toString());
}
break;
}
}
}
}
答案 0 :(得分：1)
首先，尝试在方法中分割代码：
while (action != 6) {
printIntro()
action = getAction();
switch (action) {
case 1: {
contact = readContact()
contacts.add(contact);
try {
writeContact(contact);
System.out.println("Your contact has been saved.");
}
catch (IOException e) {
e.printStackTrace();
}
}
break;
etc.
要将此东西拆分为类，首先要确定您拥有的对象。对象通常用名词表示。例如，您有一个联系人列表文件。您可以创建一个类ContactListFile，其中包含AddContact，SearchContact，GetContacts等方法。
然后你可以使用这样的代码：
contactListFile = new ContactListFile("contactlist.csv");
contact = readContact();
contactListFile.AddContacts(contact);
答案 1 :(得分：0)
这听起来像code review Stack Exchange site的候选者，但我的$ .02：打破代码来处理每个动作到他们自己的方法，并调用这些方法。一旦你得到它，你可以将循环移动到一个名为runActions（）的方法，然后从main（）调用runActions（）。
答案 2 :(得分：0)
在App类中的这个示例中，调用Test类的meth1方法：
class Test{
public void meth1(){
System.out.println("meth1 from Test Class");
}//end of meth1
}//end of class Test
public class App{
public static void main(String arg[]){
Test t = new Test();
t.meth1();
}//end of main
}//end of class App