Week7Examples

Week7/CalendarDate.java

@@ -0,0 +1,24 @@
+import java.util.Calendar;
+import java.util.Date;
+import java.text.SimpleDateFormat;
+import java.util.Locale;
+import static java.util.Calendar.*;
+
+class CalendarDate 
+{
+	public static void main(String[] args) throws java.text.ParseException
+	{
+		Calendar calendar = Calendar.getInstance();
+		calendar.roll( MONTH, 1);
+		System.out.println( calendar.get(MONTH) + "��" + calendar.get( DAY_OF_MONTH ) + "��");
+
+		Date date = new Date();
+		SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.CHINA);
+		System.out.println( formatter.format(date ));
+
+		date = new SimpleDateFormat("yyyy-MM-dd").parse( "2013-4-23" );
+		calendar.setTime( date );
+		System.out.println( calendar.getDisplayName(DAY_OF_WEEK, LONG, Locale.CHINA) );
+
+	}
+}

Week7/CalendarDate8.java

@@ -0,0 +1,44 @@
+import java.time.*;
+import java.time.format.*;
+
+class CalendarDate8{
+	public static void main(String[] args) throws java.text.ParseException
+	{
+		//ʹ��Ĭ��ʱ��ʱ��˲ʱʱ�䴴�� Clock.systemDefaultZone() -->������� ZoneId.systemDefault()Ĭ��ʱ��  
+        LocalDateTime now = LocalDateTime.now();
+        System.out.println(now);
+
+		//�Զ���ʱ��  
+        LocalDateTime now2 = LocalDateTime.now(ZoneId.of("Europe/Paris"));
+        System.out.println(now2);//������Ӧ��ʱ����ʾ����  
+
+		//����һ������  
+        LocalDateTime d1 = LocalDateTime.of(2013, 12, 31, 23, 59, 59);
+
+		//����String--->LocalDateTime  
+        LocalDateTime d4 = LocalDateTime.parse("2013-12-31T23:59:59");
+        System.out.println(d4);
+
+		//ʹ��DateTimeFormatter API ���� �� ��ʽ��  
+        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");
+        LocalDateTime d6 = LocalDateTime.parse("2013/12/31 23:59:59", formatter);
+        System.out.println(formatter.format(d6));
+
+		//ʱ���ȡ��һ����
+        System.out.println(d6.getYear());
+        System.out.println(d6.getMonth()); //�ⲻ������������ö��
+        System.out.println(d6.getDayOfYear());
+        System.out.println(d6.getDayOfMonth());
+        System.out.println(d6.getDayOfWeek());
+        System.out.println(d6.getHour());
+        System.out.println(d6.getMinute());
+        System.out.println(d6.getSecond());
+        System.out.println(d6.getNano()); //����
+
+		//ʱ������  
+        LocalDateTime d7 = d6.minusDays(1);
+        LocalDateTime d8 = d6.plusHours(1).plusMinutes(30);
+		System.out.println(d7);
+		System.out.println(d8);
+	}
+}

Week7/CayleyTree.java

@@ -0,0 +1,56 @@
+import java.awt.*;
+import javax.swing.*;
+
+public class CayleyTree extends JFrame
+{
+	public static void main( String []args ){
+		CayleyTree frm = new CayleyTree("CayleyTree");
+		frm.setVisible( true );
+		SwingUtilities.invokeLater(()->{
+			frm.init();
+			frm.drawTree( 10, 200, 400, 100, -Math.PI/2 );
+		});
+	}
+	private Frame frm;
+	private Graphics graphics;
+	private int width;
+	private int height;
+	private final double PI = Math.PI;
+	private final double th1 = 30 * PI / 180;
+	private final double th2 = 20 * PI / 180;
+	private final double per1 = 0.6;
+	private final double per2 = 0.7;
+
+	public CayleyTree(String title){
+		super(title);
+		setSize( 400, 440 );
+		setBackground( Color.lightGray );
+		setDefaultCloseOperation(EXIT_ON_CLOSE);
+	}
+
+	public void init(){
+		width = getSize().width;
+		height = getSize().height;
+		graphics = this.getGraphics();
+	}
+
+
+
+	void drawTree(int n, 
+			double x0, double y0, double leng, double th)
+	{
+		if( n==0 ) return;
+
+		double x1 = x0 + leng * Math.cos(th);
+		double y1 = y0 + leng * Math.sin(th);
+
+		drawLine(x0, y0, x1, y1);
+
+		drawTree( n - 1, x1, y1, per1 * leng, th + th1 );
+		drawTree( n - 1, x1, y1, per2 * leng, th - th2 );
+	}
+	void drawLine( double x0, double y0, double x1, double y1 ){
+		graphics.drawLine( (int)x0, (int)y0, (int)x1, (int)y1 );
+	}
+
+}

Week7/Fac.java

@@ -0,0 +1,12 @@
+public class Fac
+{
+	public static void main(String args[])
+	{
+		System.out.println("Fac of 5 is " + fac( 5) );
+	}
+	static long fac( int n ){
+		if( n==0 ) return 1;
+		else return fac(n-1) * n;
+	}
+
+}

Week7/GenericMethod.java

@@ -0,0 +1,23 @@
+import java.util.*;
+
+class GenericMethod {
+	public static void main(String[] args){ 
+		Date date = BeanUtil.<Date>getInstance("java.util.Date");
+		System.out.println(date);
+	}
+}
+
+class BeanUtil{
+	public static <T> T getInstance( String clzName ){
+		try
+		{
+			Class c = Class.forName(clzName);
+			return (T) c.newInstance();
+		}
+		catch (ClassNotFoundException ex){}
+		catch (InstantiationException ex){}
+		catch (IllegalAccessException ex){}
+		return null;
+	}
+}
+

Week7/GenericTreeClass.java

@@ -0,0 +1,34 @@
+import java.util.*;
+
+class GenericTreeClass {
+	public static void main(String[] args){ 
+		TNode<String> t = new TNode<>("Roo");
+		t.add("Left"); t.add("Middle"); t.add("Right");
+		t.getChild(0).add("aaa");
+		t.getChild(0).add("bbb");
+		t.traverse();
+	}
+}
+
+class TNode<T>
+{
+  private T value;
+  private ArrayList<TNode<T>> children = new ArrayList<>();
+
+  TNode(T v) { this.value = v; } 
+  public T getValue() { return this.value; } 
+  public void add(T v) {
+    TNode<T> child = new TNode<>(v);
+    this.children.add(child);
+  }
+  public TNode<T> getChild(int i) {
+    if ((i < 0) || (i > this.children.size())) return null;
+    return (TNode<T>)this.children.get(i);
+  }
+
+  public void traverse() {
+    System.out.println(this.value);
+    for (TNode child : this.children)
+      child.traverse();
+  }
+}

Week7/Queen8.java

@@ -0,0 +1,62 @@
+class Queen8 
+{
+	public static void main(String[] args) 
+	{
+		new Queen8().solve();
+	}
+
+	private static final int N = 8;
+	private int[]y; //��¼ÿ���ϵĻʺ�ŵ�λ��
+	int count = 0; //��ĸ���
+
+	public void solve()
+	{
+		count = 0;
+		y = new int[N+1]; //��ʼ������
+		int x = 1;
+
+		while(x>0)
+		{
+			y[x]++;	  //Ϊ��ǰxλ����һ���ʺ��λ��
+			while((y[x]<=N) && (!check(x))) y[x]++; //�ҵ����ʵĻʺ�
+			//
+			if(y[x]<=N)//�ҵ�һ�����Է��õ�x���ʺ��λ�ã����ò�Ϊֹ�����󲿷ֽⶼ����Ҫ��
+			{
+				if(x==N)//�ҵ�һ�������ķ��÷���
+				{
+					count++;
+					print();
+				}
+				else
+					x++; //����Ѱ����һ���ʺ��λ�ã���û�ҵ������������
+			}
+			else//δ�ҵ����Է��õ�x���ʺ��λ�ã����ò�Ϊֹ���Ѿ�֪��������Ҫ��
+			{
+				y[x] = 0;//��ΪҪ���ݣ���һ����Ѱ�ҵ�x-1���ʺ��λ�ã�
+				//����һ��ȷ��x-1��λ��֮�󣬵�x���ʺ�Ŀ�ʼ������λ��Ҫ����
+				x--; //����
+			}
+		}
+	}
+	private boolean check( int k) //���ԺϷ���
+	{ 
+		for(int j = 1;j < k;j++)
+			if((Math.abs(k-j) == Math.abs(y[j] - y[k]))
+				||(y[j] == y[k])) return false;
+		return true;
+	}
+
+	private void print()//��ʾ
+	{
+		System.out.println(count);
+		for( int i=1; i<=N; i ++ )
+		{
+			for( int j=1; j<=N; j++ )
+				if( j==y[i] ) System.out.print("x");//�����λ�÷��˻ʺ�����ʾx
+				else System.out.print("o");
+			System.out.println();
+		}
+
+	}
+
+}

Week7/StringAndStringBuffer.java

@@ -0,0 +1,21 @@
+import java.util.*;
+class StringAndStringBuffer 
+{
+	public static void main(String[] args) 
+	{
+		String a = "a";
+		String s = "";
+		StringBuffer sb = new StringBuffer();
+
+		final int N = 10000;
+
+		long t0 = System.currentTimeMillis();
+		for( int i=0; i<N; i++) s+=a;
+		long t1 = System.currentTimeMillis();
+		for( int i=0; i<N; i++) sb.append(a);
+		long t2 = System.currentTimeMillis();
+
+		System.out.println(t1-t0);
+		System.out.println(t2-t1);
+	}
+}

Week7/SystemProperties.java

@@ -0,0 +1,13 @@
+import java.util.*;
+class SystemProperties
+{
+	public static void main(String[] args) 
+	{
+		Properties props = System.getProperties();
+		Enumeration keys = props.propertyNames();
+		while(keys.hasMoreElements() ){
+			String key = (String) keys.nextElement();
+			System.out.println( key + " = " + props.getProperty(key) );
+		}
+	}
+}

Week7/TestArraysSort.java

@@ -0,0 +1,38 @@
+import java.util.*;
+
+public class TestArraysSort {
+    static Random r = new Random();
+    static String
+    ssource = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+    static char[] src =
+        ssource.toCharArray();
+
+    static String randString(int length) {
+        char[] buf = new char[length];
+        for(int i = 0; i < length; i++) {
+            int rnd = Math.abs(r.nextInt()) % src.length;
+            buf[i] = src[rnd];
+        }
+        return new String(buf);
+    }
+
+    static String[] randStrings(int length, int size) {
+        String[] s = new String[size];
+        for(int i = 0; i < size; i++) 
+			s[i] = randString(length);
+        return s;
+    } 
+	public static void print(String[] s) {
+        for(int i = 0; i < s.length; i++)
+            System.out.print(s[i] + " ");
+        System.out.println();
+    } 
+	public static void main(String[] args) {
+        String[] s = randStrings(4, 10);
+        print(s);
+        Arrays.<String>sort(s);
+        print(s);
+        int loc = Arrays.<String>binarySearch(s, s[2]);
+        System.out.println("Location of " + s[2] + " is " + loc);
+    }
+}

Week7/TestCollectionsSort.java

@@ -0,0 +1,51 @@
+import java.util.*;
+class TestCollectionsSort 
+{
+	public static void main(String[] args) 
+	{
+		List<Person> school = new ArrayList<>();
+		school.add( new Person("Li",23));
+		school.add( new Person("Wang",28));
+		school.add( new Person("Zhang",21));
+		school.add( new Person("Tang",19));
+		school.add( new Person("Chen",22));
+		school.add( new Person("Zhao",22));
+		System.out.println( school );
+
+		Collections.sort( school, new PersonComparator() );
+		System.out.println( school );
+
+		int index = Collections.binarySearch( 
+				school, new Person("Li",23), new PersonComparator() );
+		if( index >=0 ) 
+			System.out.println( "Found:" + school.get( index ));
+		else
+			System.out.println( "Not Found!" );
+	}
+}
+
+class Person
+{
+	String name;
+	int age;
+	public Person( String name, int age){ 
+		this.name=name;
+		this.age=age;
+	}
+	@Override
+	public String toString(){
+		return name+":"+age;
+	}
+}
+
+class PersonComparator implements Comparator
+{
+	public int compare( Object obj1, Object obj2 ){
+		Person p1 = (Person)obj1;
+		Person p2 = (Person)obj2;
+		if( p1.age > p2.age ) return 1;
+		else if(p1.age<p2.age) return -1;
+		return p1.name.compareTo( p2.name );
+	}
+}
+