Question

我正在尝试从属性文件中提取数据并将其放入地图中。更准确地说：我有一个Properties对象，其中文件包含以下内容：

something = Blah
somethingElse = BlahBlah
andAgain = BlahBlahBlah
# Parameters
param1 = One
param2 = Two
param3 = Three
# and so on...
param9 = Nine

我现在尝试使用键param...提取属性的键和值，并将它们放在TreeMap中。排序应与属性文件（param1，... param9）保持一致。到目前为止，这是我的代码：

/*
 * First extract the properties which are stored in external file
 */
Properties props = extractProperties();
Map<String, String> sortedMap = new TreeMap<String, String>();
HashMap<String, String> map = new HashMap<String, String>();
if (checkPropertiesAvailable()) {
    Enumeration e = props.propertyNames();
    // iterate over properties
    while (e.hasMoreElements()) {
        String key = (String) e.nextElement();
        // put key/value in HashMap
        map.put(key, props.getProperty(key));
        if (key.contains("param")) {
            // 
            sortedMap.put(key, props.getProperty(key));
        }
    }
    for (Map.Entry<String, String> entry : sortedMap.entrySet()) {
        system.out.println("Value: " + entry.getValue());
    }
}

不幸的是，参数（param1，... param9）未正确排序，我无法弄清楚它们目前是如何排序的。出了什么问题，我该如何对地图进行排序？

我很感激任何帮助！

Answer 1

您的代码以排序方式打印属性。请检查此代码：

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Map;
import java.util.Properties;
import java.util.TreeMap;

public class TreeMapExample {

    public static void main(String[] args) {
        Properties props = new Properties();
        try (FileInputStream input = new FileInputStream("src/main/resources/example.properties")) {
            props = new Properties();
            props.load(input);
        } catch (IOException e) {
            System.out.println("Failed to load properties from file.");
        }

        Map<String, String> sortedMap = new TreeMap<>();

        Enumeration e = props.propertyNames();
        while (e.hasMoreElements()) {
            String key = (String) e.nextElement();
            if (key.contains("param")) {
                sortedMap.put(key, props.getProperty(key));
            }
        }

        for (Map.Entry<String, String> entry : sortedMap.entrySet()) {
            System.out.printf("[Key, Value]: %s, %s \n", entry.getKey(), entry.getValue());
        }

        System.out.println();

        for (String s : sortedMap.keySet()) {
            System.out.printf("[Key, Value]: %s, %s \n", s, sortedMap.get(s));
        }

        System.out.println();

        for (String s : sortedMap.values()) {
            System.out.printf("Value: %s \n", s);
        }
    }
}

输出是： {代码}

[Key, Value]: param1, One 
[Key, Value]: param2, Two 
[Key, Value]: param3, Three 
[Key, Value]: param9, Nine 

[Key, Value]: param1, One 
[Key, Value]: param2, Two 
[Key, Value]: param3, Three 
[Key, Value]: param9, Nine 

Value: One 
Value: Two 
Value: Three 
Value: Nine

TreeMap没有正确排序

1 个答案: