java新手笔记32 jdk5新特性

1.for

package com.yfs.javase;

import java.awt.Color;
import java.util.Calendar;
import java.util.HashSet;
import java.util.Set;
@SuppressWarnings("all")
public class ForDemo {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		//useArray();
		//useSet();
		boxTest();
//
//		Calendar cal = Calendar.getInstance();
//		int year = cal.get(Calendar.YEAR);

	}
	@Deprecated
    public static void boxTest() {
		int a = 10;
		Integer oInt = new Integer(a);
		Integer o2 = a;//自动装箱
		System.out.println("o2 = " + o2);

		int b = o2 + 1;  // 自动拆箱
		System.out.println("b = " + b);
	}
	public static void useSet() {
		Set<String> set = new HashSet<String>();
		set.add("eee");
		set.add("ccc");
		set.add("aaa");
		set.add("bbb");
		set.add("yyy");
		for (Object s : set) {
			System.out.print((String)s + "\t");
		}

	}
	//增强for
	public static void useArray() {
		int[] a = {45,23,11,68,28,65,9,2,18,97};
		for(int i : a) {
			System.out.print(i + "\t");
		}

	}
	@Override//元数据
	public String toString() {
		// TODO Auto-generated method stub
		return super.toString();
	}

}

2.静态导入

package com.yfs.javase;
import static java.lang.Math.PI;//静态导入
import static java.lang.Math.sqrt;
public class StaticImport {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
	      //staticTest();
	      paramTest("java",2,3);
//	      paramTest(2,3,4,5,6);
//	      paramTest(10,20,30,40);
//	      paramTest(new int[]{45,22,61,32,78,15,24,63,98});
	}
	//变长参数  1.只能有一个 2.类型没有限制 3.可以传其他参数 必须在变长参数之前
	public static void paramTest(String name, int ... a /*, Object...obj*/) {
		int sum = 0;
		System.out.println("call paramTest(int ... a) ...");
		for (int i = 0; i < a.length; i++) {
			sum += a[i];
		}
		System.out.println("sum = " + sum);

	}

	public static void paramTest(int a,int b) {
		int sum = a + b;
		System.out.println("sum = " + sum);

	}

	public static void staticTest() {
		double area = Math.PI * 2 *2;
		area = PI* 4 * 4;
		area = PI* 6 * 6;
		double result = Math.sqrt(16);
		result = sqrt(81);
	}

}

3.Thread1继承 Thread

package com.yfs.javase.thread;

public class Thread1 extends Thread {

	public void test() {
		while( true ) {
			System.out.println("bbbbbbbbbb");
		}
	}

	@Override
	public void run() {//覆盖父类run方法
		while( true ) {
			System.out.println(Thread.currentThread().getName() + "bbbbbbbbbb");
		}
	}

}

4.Thread2实现Runnable接口

package com.yfs.javase.thread;

public class Thread2 implements Runnable {

	@Override
	public void run() {
		while(true) {
			System.out.println(Thread.currentThread().getId() + "ccccccccccc");
		}

	}

}

5.Thread1测试（单线程）

package com.yfs.javase.thread;

public class ThreadDemo1 {

	public static void main(String[] args) {

		Thread1 th1 = new Thread1();
		th1.test();

		for (int i = 0;; i++) {
			System.out.println("aaaaaaaaaaa");

		}

		//System.out.println("执行结束...");

	}

}

6.Thread2测试（多、线程启动）

package com.yfs.javase.thread;

public class ThreadDemo2 {

	public static void main(String[] args) {
        //继承Thread类
		Thread1 th1 = new Thread1();
		th1.start();//调用父类start方法

		//实现runnabel接口
        Thread2 r2 = new Thread2();
        Thread th2 = new Thread(r2);
        th2.start();

		for (int i = 0;; i++) {
			System.out.println("aaaaaaaaaaa");

		}

		//System.out.println("执行结束...");

	}

}

7.currentThread

package com.yfs.javase.thread;

public class ThreadDemo3 {
	// 线程启动
	public static void main(String[] args) throws Exception {
		// 继承Thread类
		Thread1 th1 = new Thread1();
		//th1.run();//普通方法调用  线程的执行代码============?????注意
		//启动
		th1.setName("逗你玩  ");
		th1.start();

		//接口
		Thread th2 = new Thread(new Thread2());

		th2.start();
		Thread.currentThread().setPriority(Thread.MAX_PRIORITY);===========
		for (int i = 0;; i++) {
			Thread.sleep(1);
			System.out.println( Thread.currentThread().getPriority() + "   aaaaaaaaaaa");

		}

	}

}