Java常用类库StringBuffer，Runtime，日期操作类等类库总结

package library;
 
public class RuntimeDemo {
	public static void main(String[] args) {
		Runtime run = Runtime.getRuntime();//通过Runtime类的静态方法为其进行实例化操作
		System.out.println("JVM最大内存量："+run.maxMemory());//观察最大内存量，根据机器环境会有所不同
		System.out.println("JVM空闲内存量："+run.freeMemory());//取得程序运行时的内存空闲量
		String str = "Hello"+"World"+"!!!"+"\t"+"Welcome"+"To"+"MLDN"+"~";
		System.out.println(str);
		for (int i = 0; i < 100; i++) {//循环修改Sting，产生多个垃圾，会占用内存
			str+=i;
		}
		System.out.println("操作String之后的，JVM空闲内存量："+run.freeMemory());//观察有多个垃圾空间产生之后的内存空闲量
		run.gc();//进行垃圾收集，释放空间
		System.out.println("垃圾回收之后的，JVM空闲内存量："+run.freeMemory());//垃圾收集之后的内存空闲量。
	}
}

package library;
 
import java.io.IOException;
 
/**
 * 调用本机可以执行程序
 * 让记事本进程5s后消失
 */
public class RuntimeDemo2 {
	public static void main(String[] args) {
		Runtime run = Runtime.getRuntime();//通过Runtime类的静态方法为其进行实例化操作
		Process pro = null;//声明一个Process对象，接受启动的进程
		try {
			pro = run.exec("notepad.exe");//调用本机程序，必须进行异常处理
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();//打印异常信息
		}
		try {
			Thread.sleep(5000);//让此线程存活5s
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();//打印异常信息
		}
		pro.destroy();//结束此进程
	}
}

package library;
 
import java.text.MessageFormat;
import java.util.Locale;
import java.util.ResourceBundle;
 
public class InterDemo {
	public static void main(String[] args) {
		Locale zhLoc = new Locale("zh","CN");//表示中国地区
		Locale enLoc = new Locale("en","US");
		Locale frLoc = new Locale("fr","FR");
		ResourceBundle zhrb = ResourceBundle.getBundle("Message",zhLoc);//找到中文的属性文件（.getBundle(文件名称,区域码)）
		ResourceBundle enrb = ResourceBundle.getBundle("Message",enLoc);
		ResourceBundle frrb = ResourceBundle.getBundle("Message",frLoc);
		String str1 = zhrb.getString("info");
		String str2 = enrb.getString("info");
		String str3 = frrb.getString("info");
		System.out.println("中文："+MessageFormat.format(str1, "你好"));//通过键值读取属性文件的类容
		System.out.println("英文："+MessageFormat.format(str2, "nihao"));
		System.out.println("法文："+MessageFormat.format(str3, "nihao"));
		
	}
}

protected  void finalize() throws Throwable
package library.finalize;
 
public class Person {
	private String name; 
	private int age ;
	
	public Person(String name, int age) {
		super();
		this.name = name;
		this.age = age;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	@Override
	public String toString() {
		return "年龄：age=" + age + ",姓名： name=" + name ;
	}
	public void finalize()throws Throwable{//对象释放空间时默认调用此方法
		System.out.println("对象被释放 -->"+this);//直接打印对象调用toString
	}
	
	public static void main(String[] args) {
		Person per = new Person("张三",30);
		per = null;//断开引用释放空间
		//以上代码不会在显示器显示输出
		System.gc();//强制性释放空间，，会调用fianlize()方法
	}
	
}

package library;
 
import java.util.Arrays;
 
public class ArraysDemo {
	public static void main(String[] args) {
		int temp[] = {3,5,7,9,1,2,6,8};
		Arrays.sort(temp);	//数组排序
		System.out.println("排序后数组：");
		System.out.println(Arrays.toString(temp));//以字符串输出数组
		int point = Arrays.binarySearch(temp, 3);//检索数据位置
		System.out.println("元素3的位置在："+point);
		Arrays.fill(temp, 3);					//填充数组
		System.out.println("数组填充：");
		System.out.println(Arrays.toString(temp));//一字符串输出数组
	}
}

package library.comparabledemo;
 
import java.util.Arrays;
 
public class Student implements Comparable<Student> {
 
	private String name;
	private int age;
	private float score;
	
	public Student(String name, int age, float score) {
		super();
		this.name = name;
		this.age = age;
		this.score = score;
	}
 
	@Override
	public String toString() {
		return "Student [age=" + age + ", name=" + name + ", score=" + score
				+ "]";
	}
 
	@Override
	public int compareTo(Student o) {
		if (this.score>o.score) {
			return -1;
		}else if (this.score<o.score) {
			return 1;
		} else {
			if (this.age>o.age) {
				return 1;
			}else if (this.age<o.age) {
				return -1;
			}else {
				return 0;
			}
		}
	}
	public static void main(String[] args) {
		Student stu[] = {new Student("张三",20,90.0f),new Student("王五", 20, 99.0f),
				new Student("孙七", 22, 100.0f),new Student("李四", 22, 9.0f),
				new Student("赵六", 20, 70.0f),};
		Arrays.sort(stu);
		for (int i = 0; i < stu.length; i++) {
			System.out.println(stu[i]);
		}
	}
}

package library.comparabledemo;
 
public class BinaryTree {
	class Node{											//申明一个节点类
		private Comparable data;						//保存具体类容
		private Node left;								//保存左子树
		private Node right;								//保存右子树
		
		public void addNode(Node newNode){
			if(newNode.data.compareTo(this.data)<0){
				if(this.left==null){					//放在左子树
					this.left = newNode;
				}else {
					this.left.addNode(newNode);			//递归
				}
			}
			if(newNode.data.compareTo(this.data)>=0){
				if (this.right==null) {					//放在右子树
					this.right = newNode;
				}else {
					this.right.addNode(newNode);		//递归
				}
			}
		}
		
		public void printNode(){						//输出时采用中序遍历
			if(this.left!=null){						//如果左子树有值，则递归调用该方法，该操作会将中序，root.data左边的数字现输出，而且时从小到大的顺序
				this.left.printNode();
			}
			System.out.print(this.data+"\t");			//输出root.data--->根节点
			if (this.right!=null) {						//如果右子树有值，则递归调用该方法，该操作会将中序，root.data左边的数字现输出，而且时从小到大的顺序
				this.right.printNode();
			}
		}
	}
	
	private Node root;									//根元素
	
	public void add(Comparable data){
		Node newNode = new Node();						//每传入一个数值，就声明一个新的根节点
		newNode.data = data;
		if (root == null) {
			root = newNode;								//如果是第1个元素，设置根节点
		}else {
			root.addNode(newNode);						//确定结点是放在左子树还是右子树
		}
	}
	
	public void print(){								//输出节点
		this.root.printNode();
	}
	
	public static void main(String[] args) {
		BinaryTree bt = new BinaryTree();
		bt.add(8);
		bt.add(7);
		bt.add(14);
		bt.add(10);
		bt.add(4);
		bt.add(1);
		bt.add(13);
		bt.add(6);
		bt.add(3);
		System.out.println("排序后的结果：");
		bt.print();
	}
}

package library.regex;
 
public class RegexDemo1 {
 
	public static void main(String[] args) {
		String info = "LXH:98|MLDN:90|LI:100";
		String s[] = info.split("|");			//按照“|”拆分
		System.out.println("字符串的拆分：");
		for (int i = 0; i < s.length; i++) {
			System.out.print(s[i]+"、");
		}
	}
}

package library.regex;
 
public class RegexDemo2 {
	public static void main(String[] args) {
		String info = "LXH:98|MLDN:90|LI:100";
		String s[] = info.split("\\|");			//按照“|”拆分,需要转义
		System.out.println("字符串的拆分：");
		for (int i = 0; i < s.length; i++) {
			String s2[] = s[i].split(":");
			System.out.println("\t|--"+s2[0]+"\t"+s2[1]);
		}
	}
}

package library.timer;
 
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimerTask;
 
public class MyTask extends TimerTask {			//任务调度类要继承TimmerTask类
	
	@Override
	public void run() {
		// TODO Auto-generated method stub
		SimpleDateFormat sdf = null;
		sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSSS");
		System.out.println("当前系统时间："+sdf.format(new Date()));
	}
 
}

package library.timer;
 
import java.util.Timer;
 
public class TestTask {
	public static void main(String[] args) {
		Timer t = new Timer();				//建立Timer对象
		MyTask mt = new MyTask();			//定义任务
		t.schedule(mt, 1000,2000);			//设置任务的执行，1秒后开始，每2秒重复
	}
}