java - 从Java中的字符串数组中提取

Question

这个问题已经有答案了:

How do I compare strings in Java? (23 个回答)

已关闭 7 年前。

我正在制作一个游戏，用户输入他/她的名字和姓氏。该程序从名称中提取第一个字母，然后从字符串数组中输出名称。

我认为问题出在代码的最后部分，我将字符串的第一个字母和最后一个字母与数组进行比较。但我不确定。我花了一些时间研究，但我被困住了。

欢迎任何意见。你不会伤害我的感情。

import java.util.Arrays;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Scanner; 

public abstract class ChristmasName extends JFrame implements ActionListener {


public static void main(String[] args) {

    JFrame frame = new JFrame("What is your Christmas Name?");
    frame.setVisible(true);
    frame.setSize(400,300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel panel = new JPanel();
    frame.add(panel);

    JLabel firstName = new JLabel("First name:");
        JTextField first = new JTextField(15);
    JLabel lastName = new JLabel("Last name:");
        JTextField last = new JTextField(15);
    panel.add(firstName);
    panel.add(first);
    panel.add(lastName);
    panel.add(last);

    JButton submit = new JButton("Submit");
    panel.add(submit);
    submit.addActionListener(new ActionListener() {

        @Override
        public actionPerformed(ActionEvent e) {
           String[] first_name = {"Apple","Eggnogg","Candy","Jingle","Holly","Goldie","Ho Ho","Frosty","Joyous","Mittens","Tinsel","Turkey","Tiny","Cranberry","Bloated","Angel","Bauble","Bulb","Ginger","Blitzen","Eve","Faith","Fruitcake","Goose","Glitter","Grinch"};
           String[] last_name = {"Tidings","Swan","Jolly","Claus","Mistletoe","Punch","Chimney","Coal","Igloo","Jumper","Myrhh","Pudding","Reindeer","Rejoice","Icicle","Midnight","Shepherd","Surprise","Gift","Magi","Train","Tree","White","Donkey","Wreath","Stuffing"};

           String firstLetter = first.getText();
           firstLetter = firstLetter.substring(0,1);

           String lastLetter = last.getText();
           lastLetter = lastLetter.substring(0,1);

           if (firstLetter == "A") {
               firstLetter = first_name[0];

           }



           JOptionPane.showMessageDialog(null, firstLetter + " " + lastLetter);
           System.exit(0);     
        }
    });    

}

}

Answer 1

因为您只需要一个字符，所以应该使用 charAt() 而不是 substring。虽然 substring 是可能的，但我总是忘记哪个参数是包含的或排除的。我想你也会的。

您应该声明 2 个字符:

char firstChar = first.getText().charAt(0);
char lastChar = last.getText ().charAt (0);

然后你可以检查它们:

if (firstChar == 'A') { //Remember to use single quotes!