JAVA-Properties类和Collections工具类

标签：java   collections   properities   

Properties类

import java.io.FileReader;
import java.util.Enumeration;
import java.util.Properties;

/*
 * Properties类，键值对集合，是Hashtable的子类
 * 但只能存储字符串键值对
 */
public class Test07
{
    public static void main(String[] args) throws Exception
    {
        test1();
        test2();
    }

    // Properties基本用法
    public static void test1()
    {
        // 创建一个Properties属性集合
        Properties p = new Properties();
        // 添加属性和属性值
        p.setProperty("username", "tom");
        p.setProperty("sex", "男");
        p.setProperty("hobby", "学习Java编程");
        // 根据属性名获取属性值
        String hobby = p.getProperty("hobby");
        System.out.println("hobby:" + hobby);
        // 遍历Properties集合
        System.out.println("******遍历Properties集合");
        Enumeration e = p.propertyNames();// 获取属性名的枚举实例
        while (e.hasMoreElements())
        {
            String key = (String) e.nextElement();
            String value = p.getProperty(key);
            // String value=(String) p.get(key);
            System.out.println(key + ":" + value);
        }
        System.out.println(p);
    }

    // 查看系统属性
    public static void test2()
    {
        // 获取系统的属性
        Properties p = System.getProperties();
        // 遍历输出系统属性信息
        Enumeration e = p.propertyNames();
        while (e.hasMoreElements())
        {
            String key = (String) e.nextElement();
            String value = p.getProperty(key);
            System.out.println(key + ":" + value);
        }
    }

    // 加载文件中的属性信息
    public static void test3() throws Exception
    {
        //创建文件输入流
        FileReader reader = new FileReader("student.properties");
        //创建一个Properties集合，保存属性信息
        Properties p=new Properties();
        //使用load()方法加载属性文件
        p.load(reader);
        System.out.println(p);
    }

}

运行如下：

hobby:学习Java编程
******遍历Properties集合
sex:男
hobby:学习Java编程
username:tom
{hobby=学习Java编程, sex=男, username=tom}
java.runtime.name:Java(TM) SE Runtime Environment
sun.boot.library.path:D:\Program Files (x86)\Java\jdk1.8.0_25\bin
java.vm.version:25.25-b02
java.vm.vendor:Oracle Corporation
java.vendor.url:http://java.oracle.com/
path.separator:;
java.vm.name:Java HotSpot(TM) 64-Bit Server VM
file.encoding.pkg:sun.io
user.script:
user.country:CN
sun.java.launcher:SUN_STANDARD
sun.os.patch.level:Service Pack 1
java.vm.specification.name:Java Virtual Machine Specification
user.dir:E:\workspace\Study
java.runtime.version:1.8.0_25-b18
java.awt.graphicsenv:sun.awt.Win32GraphicsEnvironment
java.endorsed.dirs:D:\Program Files (x86)\Java\jdk1.8.0_25\lib\endorsed
os.arch:amd64
java.io.tmpdir:C:\Users\ADMINI~1\AppData\Local\Temp\
line.separator:

java.vm.specification.vendor:Oracle Corporation
user.variant:
os.name:Windows 7
sun.jnu.encoding:GBK
java.library.path:D:\Program Files (x86)\Java\jdk1.8.0_25\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32;H:\安卓开发\sdk\platform-tools;.
java.specification.name:Java Platform API Specification
java.class.version:52.0
sun.management.compiler:HotSpot 64-Bit Tiered Compilers
os.version:6.1
user.home:C:\Users\Administrator
user.timezone:
java.awt.printerjob:sun.awt.windows.WPrinterJob
file.encoding:GBK
java.specification.version:1.8
user.name:Administrator
java.class.path:E:\workspace\Study\bin;C:\Users\Administrator\Desktop\HanziToPinyinTest\libs\pinyin4j-2.5.0.jar
java.vm.specification.version:1.8
sun.arch.data.model:64
java.home:D:\Program Files (x86)\Java\jdk1.8.0_25
sun.java.command:Test07
java.specification.vendor:Oracle Corporation
user.language:zh
awt.toolkit:sun.awt.windows.WToolkit
java.vm.info:mixed mode
java.version:1.8.0_25
java.ext.dirs:D:\Program Files (x86)\Java\jdk1.8.0_25\lib\ext;C:\Windows\Sun\Java\lib\ext
sun.boot.class.path:D:\Program Files (x86)\Java\jdk1.8.0_25\lib\resources.jar;D:\Program Files (x86)\Java\jdk1.8.0_25\lib\rt.jar;D:\Program Files (x86)\Java\jdk1.8.0_25\lib\sunrsasign.jar;D:\Program Files (x86)\Java\jdk1.8.0_25\lib\jsse.jar;D:\Program Files (x86)\Java\jdk1.8.0_25\lib\jce.jar;D:\Program Files (x86)\Java\jdk1.8.0_25\lib\charsets.jar;D:\Program Files (x86)\Java\jdk1.8.0_25\lib\jfr.jar;D:\Program Files (x86)\Java\jdk1.8.0_25\classes
java.vendor:Oracle Corporation
file.separator:\
java.vendor.url.bug:http://bugreport.sun.com/bugreport/
sun.cpu.endian:little
sun.io.unicode.encoding:UnicodeLittle
sun.desktop:windows
sun.cpu.isalist:amd64

Collections工具类

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/*
 * Collections工具类，用来操作集合
 * 对比Arrays工具类，用来操作数组
 */
public class Test01
{
    public static void main(String[] args)
    {
        // 创建集合
        List list = new ArrayList();
        // 向集合中添加数据
        list.add("i");
        list.add("love");
        list.add("you");
        list.add("itany");
        list.add("welcome");
        list.add("to");
        list.add("itany");
        //输出集合中的最大值和最小值
        System.out.println("最大值："+Collections.max(list));
        System.out.println("最小值："+Collections.min(list));
        //按升序排列
        System.out.println("排序前："+list);
        Collections.sort(list);
        System.out.println("排序后："+list);
        //把集合顺序反转，即降序
        //Collections.reverse(list);
        //System.out.println("降序："+list);
        //二分查找
        int index=Collections.binarySearch(list, "to");
        System.out.println("to在集合中的位置："+index);
    }
}

运行实例如下：

最大值：you
最小值：i
排序前：[i, love, you, itany, welcome, to, itany]
排序后：[i, itany, itany, love, to, welcome, you]
to在集合中的位置：4

正好分析一下Collection和Collections的区别：

JAVA-Properties类和Collections工具类

标签：java   collections   properities   

原文地址：http://blog.csdn.net/yayun0516/article/details/46048475