src/chapter5/Example11.java

@@ -1,9 +1,5 @@
 package chapter5;
 
-/**
- * 获取当前时间
- */
-
 public class Example11 {
     public static void main(String[] args) {
         long startTime = System.currentTimeMillis();

src/chapter5/Example12.java

@@ -1,21 +0,0 @@
-package chapter5;
-
-import java.util.Enumeration;
-import java.util.Properties;
-
-/**
- * 获取系统信息
- */
-public class Example12 {
-    public static void main(String[] args) {
-        // 获取当前系统信息
-        Properties prop = System.getProperties();
-        Enumeration names = prop.propertyNames();
-        while (names.hasMoreElements()) {
-            String key = (String) names.nextElement();
-            String value = prop.getProperty(key);
-            System.out.println(key + "=" + value);
-        }
-    }
-}
-

src/chapter5/Example13.java

@@ -1,28 +0,0 @@
-package chapter5;
-
-class Person implements AutoCloseable {
-    String name;
-    public Person(String name) {
-        this.name = name;
-    }
-
-    public void close() {
-        System.out.println( name + " 要被回收啦！");
-    }
-}
-
-public class Example13 {
-    public static void main(String[] args) {
-        Person p1 = new Person("小明");
-        Person p2 = new Person("大王");
-
-        p1 = null;
-        p2 = null;
-
-        System.gc();
-
-        for (int i = 0; i < 1000000; i ++) {
-            // 为了延长程序运行的时间
-        }
-    }
-}

src/chapter5/Example14.java

@@ -1,15 +0,0 @@
-package chapter5;
-
-/**
- * 获取当前虚拟机信息
- */
-
-public class Example14 {
-    public static void main(String[] args) {
-        Runtime rt = Runtime.getRuntime();
-        System.out.println("处理器个数：" + rt.availableProcessors());
-        System.out.println("空闲内存：" + rt.freeMemory()/1024/1024 + "MB");
-        System.out.println("虚拟机中的内存总量：" + rt.totalMemory()/1024/1024 + "MB");
-        System.out.println("最大可用内存：" + rt.maxMemory()/1024/1024 + "MB");
-    }
-}