计数车辆数量java

Question

这是我的停车场系统代码的一部分。我在使用'count'时遇到了一些问题。目前，我的程序为每个输入'reg no'，'high value'和'large vehicle'增加了1个计数。每次我只输入新的车辆登记号码时，我希望我的程序只添加1个？我该怎么做呢？用Java计算我不是很好。这是我到目前为止：

package carpark; 


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

public class textBox extends javax.swing.JFrame 
implements ActionListener 
    { // declare the components and variables 
    private final JLabel inputLabel,inputLabel2,inputLabel3,countLabel; 
    private final JTextField inputBox,inputBox2,inputBox3,countBox; 
    private final JButton enterButton; 
    private final JButton clearButton; 

    private int count; 
    private String sum; 
    private String inputString, countString; 
    private String sumString; 

    public textBox() 
    { // sets up the components and places them 
    this.setLayout(new FlowLayout()); 
    this.inputLabel = new JLabel("Please enter the vehicle's registration number:"); 
    this.inputBox = new JTextField(8); 
    this.inputLabel2 = new JLabel("Is this a high-value car? Enter yes or no:"); 
    this.inputBox2 = new JTextField(4); 
    this.inputLabel3 = new JLabel("Is this a large vehicle? Enter yes or no:"); 
    this.inputBox3 = new JTextField(4); 
    this.countLabel = new JLabel(" Car Count"); 
    this.countBox = new JTextField(3); 
    this.enterButton = new JButton("Enter"); 
    this.clearButton = new JButton("Clear"); 

    this.add(inputLabel); 
    this.add(inputBox); 
    this.add(inputLabel2); 
    this.add(inputBox2); 
    this.add(inputLabel3); 
    this.add(inputBox3); 
    this.inputBox.addActionListener(this); 
    this.add(countLabel); 
    this.add(countBox); 
    this.countBox.setEditable(false); 


    this.add(enterButton); 
    this.enterButton.addActionListener(this); 
    this.add(clearButton); 
    this.clearButton.addActionListener(this); 
    } 

    public void actionPerformed(ActionEvent event) 
     { // reacts to the ENTER key being pressed 
     if (event.getSource() == this.enterButton || event.getSource() == this.inputBox) 
     try 
     { 
     this.inputString = inputBox.getText(); 
     this.count += 1; 
     this.countString = Integer.toString(this.count); 
     this.countBox.setText(this.countString); 
     } 

     catch (NumberFormatException entry) 
     { 
     this.inputBox.setText(""); 
     } 
     else if (event.getSource() == this.clearButton) 
     { 
     this.inputBox.setText(""); 
     this.countBox.setText(""); 
     this.count = 0; 
     } 
     } 
    } 

Answer 1

拿一个哈希图的关键是车辆注册号码。 每当你找到一个没有出现在散列图中的车辆注册号时，就增加计数。您甚至可以使用散列表来计算每个车辆注册号码输入的次数。

package carpark; 


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

public class textBox extends javax.swing.JFrame 
implements ActionListener 
    { // declare the components and variables 
    private final JLabel inputLabel,inputLabel2,inputLabel3,countLabel; 
    private final JTextField inputBox,inputBox2,inputBox3,countBox; 
    private final JButton enterButton; 
    private final JButton clearButton; 

    private int count; 
    private String sum; 
    private String inputString, countString; 
    private String sumString; 
    private HashMap<String, Integer> countMap; 

    public textBox() 
    { // sets up the components and places them 
    this.setLayout(new FlowLayout()); 
    this.inputLabel = new JLabel("Please enter the vehicle's registration number:"); 
    this.inputBox = new JTextField(8); 
    this.inputLabel2 = new JLabel("Is this a high-value car? Enter yes or no:"); 
    this.inputBox2 = new JTextField(4); 
    this.inputLabel3 = new JLabel("Is this a large vehicle? Enter yes or no:"); 
    this.inputBox3 = new JTextField(4); 
    this.countLabel = new JLabel(" Car Count"); 
    this.countBox = new JTextField(3); 
    this.enterButton = new JButton("Enter"); 
    this.clearButton = new JButton("Clear"); 
    this.countMap = new HashMap<String, Integer>(); 
    this.add(inputLabel); 
    this.add(inputBox); 
    this.add(inputLabel2); 
    this.add(inputBox2); 
    this.add(inputLabel3); 
    this.add(inputBox3); 
    this.inputBox.addActionListener(this); 
    this.add(countLabel); 
    this.add(countBox); 
    this.countBox.setEditable(false); 


    this.add(enterButton); 
    this.enterButton.addActionListener(this); 
    this.add(clearButton); 
    this.clearButton.addActionListener(this); 
    } 

    public void actionPerformed(ActionEvent event) 
     { // reacts to the ENTER key being pressed 
     if (event.getSource() == this.enterButton || event.getSource() == this.inputBox) 
     try 
     { 
     this.inputString = inputBox.getText(); 
     //If the hashmap does not contain the key, increment the count and put the registration number as the key into it. 
     if(!this.countMap.containsKey(this.inputString)) { 
      this.count += 1; 
      this.countMap.put(this.inputString, 1); 
     } 
     //Else you can increment the count in the hashmap. 
     this.countString = Integer.toString(this.count); 
     this.countBox.setText(this.countString); 
     } 

     catch (NumberFormatException entry) 
     { 
     this.inputBox.setText(""); 
     } 
     else if (event.getSource() == this.clearButton) 
     { 
     this.inputBox.setText(""); 
     this.countBox.setText(""); 
     this.count = 0; 
     } 
     } 
    }