每次程序运行时递增数字。

huangapple
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英文:

Increment number every time program runs

问题

我想在每次运行我的程序时递增计数。我尝试运行下面的代码，但每次运行程序时它都只打印1。另外，是否有任何特殊操作需要执行以增加日期。

public class CounterTest {
    int count = 0;
    public static void main(String[] args) {
        CounterTest test1 = new CounterTest();
        test1.doMethod();
    }
    public void doMethod() {
        count++;
        System.out.println(count);
    }
}
英文:

I want to increment the count every time my program runs. I tried running below code but it keeps on printing 1 every time i run the program. Also anything special i need to do to increase the date.

public class CounterTest {
    int count = 0;
    public static void main(String[] args) {
    	CounterTest test1 = new CounterTest();
        test1.doMethod();
    }
    public void doMethod() {
        count++;
        System.out.println(count);
    }
}

答案1

得分: 2

你可以为你的应用程序简单地创建一个属性文件，用来追踪这类事物和应用程序的配置细节。当然，这个文件将是一个包含属性名称（键）及其相应值的简单文本文件。

以下是两个小方法可以帮助你开始：

setProperty() 方法：

使用这个方法，你可以创建一个属性文件，并应用任何你喜欢的属性名称和值。如果文件不存在，它会在指定的文件路径自动创建：

public static boolean setProperty(String propertiesFilePath,
                                  String propertyName, String value) {
    
    java.util.Properties prop = new java.util.Properties();
    if (new java.io.File(propertiesFilePath).exists()) {
        try (java.io.FileInputStream in = new java.io.FileInputStream(propertiesFilePath)) {
            prop.load(in);
        }
        catch (java.io.FileNotFoundException ex) { System.err.println(ex); }
        catch (java.io.IOException ex) { System.err.println(ex); }
    }
    
    try (java.io.FileOutputStream outputStream = new java.io.FileOutputStream(propertiesFilePath)) {
        prop.setProperty(propertyName, value);
        prop.store(outputStream, null);
        outputStream.close();
        return true;
    }
    catch (java.io.FileNotFoundException ex) {
        System.err.println(ex);
    }
    catch (java.io.IOException ex) {
        System.err.println(ex);
    }
    return false;
}

如果你还没有特定的属性文件，那么在应用程序启动时（可能是初始化之后）调用上述方法是个好主意，这样你就可以有默认值可供使用，例如：

if (!new File("config.properties").exists()) {
    setProperty("config.properties", "ApplicationRunCount", "0");
}

上面的代码会检查是否已经存在名为 config.properties 的属性文件（你应该总是使用 .properties 文件扩展名）。如果不存在，它会创建该文件，并将属性名（键）以及提供的值应用到其中。在上面的示例中，我们正在创建 ApplicationRunCount 属性，这基本上是为你的特定需求而设的。当你查看创建的 config.properties 文件时，会看到：

#Mon Sep 28 19:07:08 PDT 2020
ApplicationRunCount=0

getProperty() 方法：

这个方法可以从特定的属性名称（键）中检索值。每当你需要从属性文件中获取特定属性的值时，可以使用这个方法：

public static String getProperty(String propertiesFilePath, String key) {
    try (java.io.InputStream ips = new java.io.FileInputStream(propertiesFilePath)) {
        java.util.Properties prop = new java.util.Properties();
        prop.load(ips);
        return prop.getProperty(key);
    }
    catch (java.io.FileNotFoundException ex) { System.err.println(ex); }
    catch (java.io.IOException ex) { System.err.println(ex); }
    return null;
}

你的任务：

让人困惑的是，你说你想要追踪你的 程序 运行的次数，但你在名为 doMethod() 的方法中递增了名为 count 的计数变量。如果你可以保证这个方法在整个应用程序运行期间只运行一次，那么这将起作用。如果不是这种情况，你可能会得到一个不真实地表示应用程序启动次数的计数总数。
无论如何，根据你目前使用的方案，你可以这样做：

public class CounterTest {

    // 类构造函数
    public CounterTest() {
        /* 如果 config.properties 文件不存在，
           则创建它并应用 ApplicationRunCount
           属性，值为 0。             */
        if (!new java.io.File("config.properties").exists()) {
            setProperty("config.properties", "ApplicationRunCount", "0");
        }
    }
    
    public static void main(String[] args) {
        new CounterTest().doMethod(args);
    }

    private void doMethod(String[] args) {
        int count = Integer.valueOf(getProperty("config.properties", 
                                                "ApplicationRunCount"));
        count++;
        setProperty("config.properties", "ApplicationRunCount", 
                    String.valueOf(count));
        System.out.println(count);
    }

    public static String getProperty(String propertiesFilePath, String key) {
        try (java.io.InputStream ips = new 
                           java.io.FileInputStream(propertiesFilePath)) {
            java.util.Properties prop = new java.util.Properties();
            prop.load(ips);
            return prop.getProperty(key);
        }
        catch (java.io.FileNotFoundException ex) { System.err.println(ex); }
        catch (java.io.IOException ex) { System.err.println(ex); }
        return null;
    }

    public static boolean setProperty(String propertiesFilePath,
                                      String propertyName, String value) {
        java.util.Properties prop = new java.util.Properties();
        if (new java.io.File(propertiesFilePath).exists()) {
            try (java.io.FileInputStream in = new java.io.FileInputStream(propertiesFilePath)) {
                prop.load(in);
            }
            catch (java.io.FileNotFoundException ex) { System.err.println(ex); }
            catch (java.io.IOException ex) { System.err.println(ex); }
        }
    
        try (java.io.FileOutputStream outputStream = new java.io.FileOutputStream(propertiesFilePath)) {
            prop.setProperty(propertyName, value);
            prop.store(outputStream, null);
            return true;
        }
        catch (java.io.FileNotFoundException ex) {
            System.err.println(ex);
        }
        catch (java.io.IOException ex) {
            System.err.println(ex);
        }
        return false;
    }
}

每当你启动应用程序时，你将在控制台窗口中看到运行计数。其他有用的方法可能是 removeProperty() 和 renameProperty()。以下是它们：

/**
 * 从提供的属性文件中删除指定的属性名。<br>
 * 
 * @param propertiesFilePath（String）要从中删除属性名的属性文件的完整路径和文件名。<br>
 * 
 * @param propertyName（String）要从属性文件中删除的属性名。<br>
 * 
 * @return（布尔值）如果成功则返回 true，否则返回 false。
 */
public static boolean removeProperty(String propertiesFilePath,
                                  String propertyName) {
    java.util.Properties prop = new java.util.Properties();
    if (new java.io.File(propertiesFilePath).exists()) {
        try (java.io.FileInputStream in = new java.io.FileInputStream(propertiesFilePath)) {
            prop.load(in);
            prop.remove(propertyName);
        }
        catch (java.io.FileNotFoundException ex) { System.err.println(ex); return false; }
        catch (java.io.IOException ex) { System.err.println(ex); return false; }
    }
    
    try (java.io.FileOutputStream out = new java.io.FileOutputStream(properties

<details>
<summary>英文:</summary>

You could simply create a properties file for your application to keep track of such things and application configuration details. This of course would be a simple text file containing property names (keys) and their respective values.

Two small methods can get you going:

&gt; **The *setProperty()* Method:**

With is method you can create a properties file and apply whatever property names and values you like. If the file doesn&#39;t already exist then it is automatically created at the file path specified:

    public static boolean setProperty(String propertiesFilePath,
                                      String propertyName, String value) {
        
        java.util.Properties prop = new java.util.Properties();
        if (new java.io.File(propertiesFilePath).exists()) {
            try (java.io.FileInputStream in = new java.io.FileInputStream(propertiesFilePath)) {
                prop.load(in);
            }
            catch (java.io.FileNotFoundException ex) { System.err.println(ex); }
            catch (java.io.IOException ex) { System.err.println(ex); }
        }
        
        try (java.io.FileOutputStream outputStream = new java.io.FileOutputStream(propertiesFilePath)) {
            prop.setProperty(propertyName, value);
            prop.store(outputStream, null);
            outputStream.close();
            return true;
        }
        catch (java.io.FileNotFoundException ex) {
            System.err.println(ex);
        }
        catch (java.io.IOException ex) {
            System.err.println(ex);
        }
        return false;
    }   

If you don&#39;t already contain a specific properties file then it would be a good idea to call the above method as soon as the application starts (perhaps after initialization) so that you have default values to play with if desired, for example:

    if (!new File(&quot;config.properties&quot;).exists()) {
        setProperty(&quot;config.properties&quot;, &quot;ApplicationRunCount&quot;, &quot;0&quot;);
    }

The above code checks to see if the properties file named **config.properties** already exists (you should always use the `.properties` file name extension). If it doesn&#39;t then it is created and the property name (Key) is applied to it along with the supplied value for that property. Above we are creating the **ApplicationRunCount** property which is basically for your specific needs. When you look into the **config.properties** file created you will see:

    #Mon Sep 28 19:07:08 PDT 2020
    ApplicationRunCount=0

&gt; **The *getProperty()* Method:**

This method can retrieve a value from a specific property name (key). Whenever you need the value from a particular property contained within your properties file then this method can be used:

    public static String getProperty(String propertiesFilePath, String key) {
        try (java.io.InputStream ips = new java.io.FileInputStream(propertiesFilePath)) {
            java.util.Properties prop = new java.util.Properties();
            prop.load(ips);
            return prop.getProperty(key);
        }
        catch (java.io.FileNotFoundException ex) { System.err.println(ex); }
        catch (java.io.IOException ex) { System.err.println(ex); }
        return null;
    }

&gt; **Your Task:**

What is confusing here is you say you want to keep track of the number of times your **Program** is run yet you increment your counter variable named **count** within a method named **doMethod()**. This would work if you can guarantee that this method will only run once during the entire time your application runs. If this will indeed be the case then you&#39;re okay. If it isn&#39;t then you would possibly get a count total that doesn&#39;t truly represent the actual number of times your application was started.
In any case, with the scheme you&#39;re currently using, you could do this:

    public class CounterTest {

        // Class Constructor
        public CounterTest() {
            /* If the config.properties file does not exist
               then create it and apply the ApplicationRunCount
               property with the value of 0.             */
            if (!new java.io.File(&quot;config.properties&quot;).exists()) {
                setProperty(&quot;config.properties&quot;, &quot;ApplicationRunCount&quot;, &quot;0&quot;);
            }
        }
        
        public static void main(String[] args) {
            new CounterTest().doMethod(args);
        }

        private void doMethod(String[] args) {
            int count = Integer.valueOf(getProperty(&quot;config.properties&quot;, 
                                                    &quot;ApplicationRunCount&quot;));
            count++;
            setProperty(&quot;config.properties&quot;, &quot;ApplicationRunCount&quot;, 
                        String.valueOf(count));
            System.out.println(count);
        }

        public static String getProperty(String propertiesFilePath, String key) {
            try (java.io.InputStream ips = new 
                               java.io.FileInputStream(propertiesFilePath)) {
                java.util.Properties prop = new java.util.Properties();
                prop.load(ips);
                return prop.getProperty(key);
            }
            catch (java.io.FileNotFoundException ex) { System.err.println(ex); }
            catch (java.io.IOException ex) { System.err.println(ex); }
            return null;
        }

        public static boolean setProperty(String propertiesFilePath,
                                          String propertyName, String value) {
            java.util.Properties prop = new java.util.Properties();
            if (new java.io.File(propertiesFilePath).exists()) {
                try (java.io.FileInputStream in = new java.io.FileInputStream(propertiesFilePath)) {
                    prop.load(in);
                }
                catch (java.io.FileNotFoundException ex) { System.err.println(ex); }
                catch (java.io.IOException ex) { System.err.println(ex); }
            }
        
            try (java.io.FileOutputStream outputStream = new java.io.FileOutputStream(propertiesFilePath)) {
                prop.setProperty(propertyName, value);
                prop.store(outputStream, null);
                return true;
            }
            catch (java.io.FileNotFoundException ex) {
                System.err.println(ex);
            }
            catch (java.io.IOException ex) {
                System.err.println(ex);
            }
            return false;
        }
    }

Whenever you start your application you will see the run count within the Console Window. Other useful methods might be **removeProperty()** and **renameProperty()**. Here they are:

    /**
     * Removes (deletes) the supplied property name from the supplied property 
     * file.&lt;br&gt;
     * 
     * @param propertiesFilePath (String) The full path and file name of the 
     * properties file you want to remove a property name from.&lt;br&gt;
     * 
     * @param propertyName (String) The property name you want to remove from 
     * the properties file.&lt;br&gt;
     * 
     * @return (Boolean) Returns true if successful and false if not.
     */
    public static boolean removeProperty(String propertiesFilePath,
                                      String propertyName) {
        java.util.Properties prop = new java.util.Properties();
        if (new java.io.File(propertiesFilePath).exists()) {
            try (java.io.FileInputStream in = new java.io.FileInputStream(propertiesFilePath)) {
                prop.load(in);
                prop.remove(propertyName);
            }
            catch (java.io.FileNotFoundException ex) { System.err.println(ex); return false; }
            catch (java.io.IOException ex) { System.err.println(ex); return false; }
        }
        
        try (java.io.FileOutputStream out = new java.io.FileOutputStream(propertiesFilePath)) {
            prop.store(out, null);
            return true;
        }
        catch (java.io.FileNotFoundException ex) { System.err.println(ex); }
        catch (java.io.IOException ex) { System.err.println(ex); }
        return false;
    }
    
    /**
     * Renames the supplied property name within the supplied property file.&lt;br&gt;
     * 
     * @param propertiesFilePath (String) The full path and file name of the 
     * properties file you want to rename a property in.&lt;br&gt;
     * 
     * @param oldPropertyName (String) The current name of the property you want 
     * to rename.&lt;br&gt;
     * 
     * @param newPropertyName (String) The new property name you want to use.&lt;br&gt;
     * 
     * @return (Boolean) Returns true if successful and false if not.
     */
    public static boolean renameProperty(String propertiesFilePath, String oldPropertyName,
                                         String newPropertyName) {
        String propertyValue = getProperty(propertiesFilePath, oldPropertyName);
        if (propertyValue == null) { return false; }
        
        java.util.Properties prop = new java.util.Properties();
        if (new java.io.File(propertiesFilePath).exists()) {
            try (java.io.FileInputStream in = new java.io.FileInputStream(propertiesFilePath)) {
                prop.load(in);
                prop.remove(oldPropertyName);
            }
            catch (java.io.FileNotFoundException ex) { System.err.println(ex); return false; }
            catch (java.io.IOException ex) { System.err.println(ex); return false ;}
        }
        
        try (java.io.FileOutputStream out = new java.io.FileOutputStream(propertiesFilePath)) {
            prop.store(out, null);
        }
        catch (java.io.FileNotFoundException ex) { System.err.println(ex); return false; }
        catch (java.io.IOException ex) { System.err.println(ex); return false; }
        
        return setProperty(propertiesFilePath, newPropertyName, propertyValue);
    }

</details>



# 答案2
**得分**: 1

请尝试这个。

```java
public class CounterTest {

    static final Path path = Path.of("counter.txt");
    int count;

    CounterTest() throws IOException {
        try {
            count = Integer.valueOf(Files.readString(path));
        } catch (NoSuchFileException | NumberFormatException e) {
            count = 0;
        }
    }

    public void doMethod() throws IOException {
        ++count;
        System.out.println(count);
        Files.writeString(path, "" + count);
    }

    public static void main(String[] args) throws IOException {
        CounterTest c = new CounterTest();
        c.doMethod();
    }

}
英文:

Try this.

public class CounterTest {
static final Path path = Path.of(&quot;counter.txt&quot;);
int count;
CounterTest() throws IOException {
try {
count = Integer.valueOf(Files.readString(path));
} catch (NoSuchFileException | NumberFormatException e) {
count = 0;
}
}
public void doMethod() throws IOException {
++count;
System.out.println(count);
Files.writeString(path, &quot;&quot; + count);
}
public static void main(String[] args) throws IOException {
CounterTest c = new CounterTest();
c.doMethod();
}
}

答案3

得分: 0

以下是翻译好的部分：

你无法唯一的方法是使用数据库，或者更简单地使用txt文件来保存数字，每次运行应用程序时都读取txt文件并获取数字。

以下是如何实现的：

这是主类：

package main;

import java.io.File;
import java.io.IOException;

public class Main {
    public static void main(String[] args) {
        String path = "C:\\Example.txt";
        int number = 0;
        try {
            ReadFile file = new ReadFile(path);
            String[] aryLines = file.OpenFile();
            try {
                number = Integer.parseInt(aryLines[0]);
            } catch (Exception e) {
            }
        } catch (IOException e) {
            System.out.println(e.getMessage());
        }
        System.out.println(number);
        number++;

        File txtfile = new File(path);
        if (txtfile.exists()) {
            txtfile.delete();

            try {
                txtfile.createNewFile();
                WriteFile data = new WriteFile(path, true);
                data.writeToFile(number + "");
            } catch (IOException ex) {
            }
        } else {
            try {
                System.out.println("no yei");
                txtfile.createNewFile();
                WriteFile data = new WriteFile(path, true);
                data.writeToFile(number + "");
            } catch (IOException ex) {
            }
        }
    }
}

写入所需内容的类：

package main;

import java.io.FileWriter;
import java.io.PrintWriter;
import java.io.IOException;

public class WriteFile {

    public String path;
    public boolean append_to_file = false;

    public WriteFile(String file_path) {
        path = file_path;
    }

    public WriteFile(String file_path, boolean append_value) {
        path = file_path;
        append_to_file = append_value;
    }

    public void writeToFile(String textline) throws IOException {
        FileWriter write = new FileWriter(path, append_to_file);
        PrintWriter print_line = new PrintWriter(write);

        print_line.printf("%s" + "%n", textline);

        print_line.close();
    }
}

获取文件中文本内容的类：

package main;

import java.io.IOException;
import java.io.FileReader;
import java.io.BufferedReader;

public class ReadFile {
    private static String path;

    public ReadFile(String file_path){
        path = file_path;
    }
    public String[] OpenFile() throws IOException {
        FileReader fr = new FileReader(path);
        BufferedReader textReader = new BufferedReader(fr);

        int numberOfLines = readLines();
        String[] textData = new String[numberOfLines];

        for (int j = 0; j < numberOfLines; j++) {
            textData[j] = textReader.readLine();
        }

        textReader.close();
        return textData;
    }
    static int readLines() throws IOException {
        FileReader file_to_read = new FileReader(path);
        BufferedReader bf = new BufferedReader(file_to_read);

        String aLine;
        int numberOfLines = 0;

        while((aLine = bf.readLine()) != null){
            numberOfLines++;
        }
        bf.close();
        return numberOfLines;
    }
}
英文:

You can't the only way is to use a Database or simpler use a txt file to save the number and every time you run your app reads the txt file and gets the number.

Here is How to do it:

This is the Main class:

package main;
import java.io.File;
import java.io.IOException;
public class Main {
public static void main(String[] args) {
String path = &quot;C:\\Example.txt&quot;;
int number = 0;
try {
ReadFile file = new ReadFile(path);
String[] aryLines = file.OpenFile();
try {
number = Integer.parseInt(aryLines[0]);
} catch (Exception e) {
}
} catch (IOException e) {
System.out.println(e.getMessage());
}
System.out.println(number);
number++;
File txtfile = new File(path);
if (txtfile.exists()) {
txtfile.delete();
try {
txtfile.createNewFile();
WriteFile data = new WriteFile(path, true);
data.writeToFile(number + &quot;&quot;);
} catch (IOException ex) {
}
} else {
try {
System.out.println(&quot;no yei&quot;);
txtfile.createNewFile();
WriteFile data = new WriteFile(path, true);
data.writeToFile(number + &quot;&quot;);
} catch (IOException ex) {
}
}
}
}

the class that writes anything you need:

package main;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.io.IOException;
public class WriteFile {
public String path;
public boolean append_to_file = false;
public WriteFile(String file_path) {
path = file_path;
}
public WriteFile(String file_path, boolean append_value) {
path = file_path;
append_to_file = append_value;
}
public void writeToFile(String textline) throws IOException {
FileWriter write = new FileWriter(path, append_to_file);
PrintWriter print_line = new PrintWriter(write);
print_line.printf(&quot;%s&quot; + &quot;%n&quot;, textline);
print_line.close();
}
}

And this one is the one that gets the text on the file:

package main;
import java.io.IOException;
import java.io.FileReader;
import java.io.BufferedReader;
public class ReadFile {
private static String path;
public ReadFile(String file_path){
path = file_path;
}
public String[] OpenFile() throws IOException {
FileReader fr = new FileReader(path);
BufferedReader textReader = new BufferedReader(fr);
int numberOfLines = readLines();
String[] textData = new String[numberOfLines];
for (int j = 0; j &lt; numberOfLines; j++) {
textData[j] = textReader.readLine();
}
textReader.close();
return textData;
}
static int readLines() throws IOException {
FileReader file_to_read = new FileReader(path);
BufferedReader bf = new BufferedReader(file_to_read);
String aLine;
int numberOfLines = 0;
while((aLine = bf.readLine()) != null){
numberOfLines++;
}
bf.close();
return numberOfLines;
}
}

huangapple
  • 本文由 发表于 2020年9月29日 08:54:13
  • 转载请务必保留本文链接：https://go.coder-hub.com/64111437.html
  • java
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