如何找到以用户输入的字母开头的名称？

Question

I have created an ArrayList to store names of customers. I then have filled the list with some names.

Now I want to ask the user to enter a letter and then find all names starting with the entered letter and all names containing the entered letter.

That's where I am upto now:

    package costomersearching;

import java.util.ArrayList;
import java.util.Scanner;

public class CostomerSearching {

    public static void main(String[] args) {
        ArrayList<String> customerName = new ArrayList();
        Scanner input = new Scanner(System.in);
        customerName.add("Sara");
        customerName.add("John");
        customerName.add("Miami");
        customerName.add("Mart");
        customerName.add("Alex");

        System.out.println("Customer List: \n" + customerName);
        System.out.println("Search Customer by letter: ");
        String letter = input.next();
        //show the name containg the letter starting as the first letter
        //Show the name containing the letetr.
    }

}

Answer 1

Simple iterate over your ArrayList and search for the right names. You could do it like this:

//show names containing the letter starting as the first letter
for(String i : costumerName) {
    if(i.startsWith(letter)) System.out.println(i);
}

//show names containing the letter
for(String i : costumerName) {
    if(i.contains(letter)) System.out.println(i);
}

Hope this helps :)

Answer 2

The methods you are searching for are startsWith(String) and contains(CharSequence) of class String. In addition, that way it will also work with more than one letter.

Just loop through you list of customers and check the names. As soon as you find a matching one, you add it to your list of customers you want to print to the user afterwards.

String searchterm = "s"; // You read the string from console

// Existing customers
ArrayList<String> customerNames = new ArrayList<String>();

// A list of customer names starting with the search term
ArrayList<String> matchesStarting = new ArrayList<String>();

// A list of customer names containing the search term
ArrayList<String> matchesContaining = new ArrayList<String>();

// Iterate over customers and check for each one if it matches the search term
for(String customer: customerNames) {

    // If it starts with the search term, add it to the list of start matches
    if(customer.startsWith(searchterm))
        matchesStarting.add(customer);

    // If it contains the search term, add it to the list of start matches
    if(customer.contains(searchterm))
        matchesContaining.add(customer);
 }

Answer 3

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;


public class TestStack {
    public static void main(String[] args) {
        Scanner input = null ;
        try{
            ArrayList<String> customerName = new ArrayList<>();
            input = new Scanner(System.in);
            customerName.add("Sara");
            customerName.add("John");
            customerName.add("Miami");
            customerName.add("Mart");
            customerName.add("Alex");

            System.out.println("Customer List: \n" + customerName);
            System.out.println("Search Customer by letter: ");
            String letter = input.next();

            List<String> searchResult = new ArrayList<>();
            for (String string : customerName) {
                  if(string.contains(letter))
                     searchResult.add(string);
             }

            List<String> searchResultStartsWithSpecifiedLetters = new ArrayList<>();
            for (String string : customerName) {
                if(string.startsWith(letter))
                    searchResult.add(string);
            }

            System.out.println("Displaying result containing entered letters");
            // Displays result containing those letters
            for (String string : searchResult) {
                System.out.println(string);
            }

            System.out.println("Displaying result starts with entered letters");
            // Displays result starts with those letters
            for (String string : searchResultStartsWithSpecifiedLetters) {
                System.out.println(string);
            }
        }finally{
            input.close();
        }
    }
}