Java程序通过Map.Entry读取映射
要阅读映射，请先使用getProperties()广告，然后使用迭代器遍历整个映射列表-
Properties prop = System.getProperties(); Iterator i = prop.entrySet().iterator();
现在，遍历Map.Entry并获取Map的键值对-
while (i.hasNext()) {
Map.Entry entry = (Map.Entry) i.next();
System.out.println(entry.getKey() + " => " + entry.getValue());
}示例
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
public class Demo {
public static void main(String[] a) {
Properties prop = System.getProperties();
Iterator i = prop.entrySet().iterator();
while (i.hasNext()) {
Map.Entry entry = (Map.Entry) i.next();
System.out.println(entry.getKey() + " => " + entry.getValue());
}
}
}输出结果
sun.desktop => windows awt.toolkit => sun.awt.windows.WToolkit java.specification.version => 11 sun.cpu.isalist => amd64 sun.jnu.encoding => Cp1252 java.class.path => java.vm.vendor => Oracle Corporation sun.arch.data.model => 64 user.variant => java.vendor.url => http://java.oracle.com/ user.timezone => os.name => Windows 10 java.vm.specification.version => 11 sun.java.launcher => SUN_STANDARD user.country => US sun.boot.library.path => C:\Program Files\Java\jdk-11.0.2\bin sun.java.command => Amit/my.Demo jdk.debug => release sun.cpu.endian => little user.home => C:\Users\amit_ user.language => en java.specification.vendor => Oracle Corporation jdk.module.path => C:\Users\amit_\eclipse-workspace3\Amit\bin;C:\Users\amit_\Downloads\javatuples-1.2.jar\javatuples-1.2.jar java.version.date => 2019-01-15 java.home => C:\Program Files\Java\jdk-11.0.2 file.separator => \ java.vm.compressedOopsMode => Zero based line.separator => java.specification.name => Java Platform API Specification java.vm.specification.vendor => Oracle Corporation java.awt.graphicsenv => sun.awt.Win32GraphicsEnvironment jdk.module.main.class => my.Demo jdk.module.main => Amit user.script => sun.management.compiler => HotSpot 64-Bit Tiered Compilers java.runtime.version => 11.0.2+9-LTS user.name => amit_ path.separator => ; os.version => 10.0 java.runtime.name => Java(TM) SE Runtime Environment file.encoding => Cp1252 java.vm.name => Java HotSpot(TM) 64-Bit Server VM java.vendor.version => 18.9 java.vendor.url.bug => http://bugreport.java.com/bugreport/ java.io.tmpdir => C:\Users\amit_\AppData\Local\Temp\ java.version => 11.0.2 user.dir => C:\Users\amit_\eclipse-workspace3\Amit os.arch => amd64 java.vm.specification.name => Java Virtual Machine Specification java.awt.printerjob => sun.awt.windows.WPrinterJob sun.os.patch.level => java.library.path => C:\Program Files\Java\jdk-11.0.2\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:/Program Files/Java/jdk-11.0.2/bin/server;C:/Program Files/Java/jdk-11.0.2/bin;C:\Program Files (x86)\ImageMagick-7.0.8-Q16;C:\Program Files\ImageMagick-7.0.8-Q16;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\GtkSharp\2.12\bin;C:\WINDOWS\System32\OpenSSH\;C:\Program Files\Java\jdk-11.0.2\bin;C:\xampp\apache\bin;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Users\amit_\AppData\Local\Microsoft\WindowsApps;;C:\WINDOWS\system32;;. java.vendor => Oracle Corporation java.vm.info => mixed mode java.vm.version => 11.0.2+9-LTS sun.io.unicode.encoding => UnicodeLittle java.class.version => 55.0