迅雷亲历面经：笔试+上机+面试（完整JAVA面试题求解大讨论）

import java.util.Arrays;
import java.util.Date;
import java.util.regex.*;
public class DTest {  
	public void test1(){
		char[] chars="6sabcsssfsfs33".toCharArray();
		boolean[] removeChars = new boolean[256];  
		removeChars['a'] = true;  
		removeChars['b'] = true;  
		removeChars['3'] = true;  
		StringBuffer sb = new StringBuffer();  
		for (int i = 0; i < chars.length; i++) {  
			if (!removeChars[chars[i]]) {
				sb.append(chars[i]);  
			}
		}    
		//System.out.println(sb.toString());  
	}
	public void test2(){
		char[] chars="6sabcsssfsfs33".toCharArray();
		StringBuffer sb=new StringBuffer();
		for(int i=0;i<chars.length;i++){
			if(chars[i]=='a'||chars[i]=='b'||chars[i]=='3'){
				continue;
			}
			sb.append(chars[i]);
		}
		//System.out.println(sb.toString());  
	}
	public void test3(){
		String regx="[^a|b|3]";  
    	String temp="6sabcsssfsfs33";  
    	Pattern p=Pattern.compile(regx);  
    	Matcher m=p.matcher(temp);  
    	StringBuffer sb=new StringBuffer();
    	while(m.find())  {
    		sb.append(m.group());
    	}
     	//System.out.print(sb); 
	}
	public static void main(String args[]) {   
		DTest dt=new DTest();
		Date now1=new Date();
		for(int i=0;i<100000;i++){
			dt.test1();
		}
		Date now2=new Date();
		System.out.println(now2.getTime()+"-"+now1.getTime()+",共用："+(now2.getTime()-now1.getTime()));
		Date now3=new Date();
		for(int i=0;i<100000;i++){
			dt.test2();
		}
		Date now4=new Date();
		System.out.println(now4.getTime()+"-"+now3.getTime()+",共用："+(now4.getTime()-now3.getTime()));
		
		Date now5=new Date();
		for(int i=0;i<100000;i++){
			dt.test3();
		}
		Date now6=new Date();
		System.out.println(now6.getTime()+"-"+now5.getTime()+",共用："+(now6.getTime()-now5.getTime()));
		
	}   
}  

		StringBuilder sb = new StringBuilder("6sabcsssfsfs33");
		sb.delete(2, 4);
		sb.delete(sb.length()-2, sb.length());

StringBuilder sb = new StringBuilder("6sabcsssfsfs33");
//使用“眼睛”去掉ab3
System.out.println("6scsssfsfs");

class MyWorker implements Runnable {

	private static Semaphore[] semaphores = { new Semaphore(1),
			new Semaphore(0), new Semaphore(0) };

	private int index = 0;
	private int count = 0;

	public MyWorker(int index) {
		this.index = index;
	}

	public static void main(String[] args) {
		new Thread(new MyWorker(0), "A").start();
		new Thread(new MyWorker(1), "B").start();
		new Thread(new MyWorker(2), "C").start();
	}

	public void run() {
		for (;;) {
			try {
				semaphores[index].acquire();
				System.out.println(Thread.currentThread().getName());
				count++;
				semaphores[(index + 1) % 3].release();
				if (count >= 10)
					break;
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
}

package ThreadTest;

import java.util.concurrent.Semaphore;

/**
 * 
 * @author zhangdepeng318@gmail.com
 * 
 */
public class TestOderThread {

	private static Semaphore semaphore1 = new Semaphore(0);
	private static Semaphore semaphore2 = new Semaphore(0);
	private static Semaphore semaphore3 = new Semaphore(0);
	public Thread t1;
	public Thread t2;
	public Thread t3;
	public volatile boolean x1 = true, x2 = true, x3 = true;

	public TestOderThread() {
		t1 = new Thread() {
			public void run() {
				try {
					semaphore1.acquire();// 必须先获得 锁才可以继续，要等release释放的。
					System.out.print("B");
					semaphore2.release();
					semaphore3.acquire();
					x1 = false;
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		};
		t2 = new Thread() {
			public void run() {
				System.out.print("A");
				semaphore1.release();
				x2 = false;
			}
		};
		t3 = new Thread() {
			public void run() {
				try {
					semaphore2.acquire();
					System.out.print("C");
					semaphore3.release();
					x3 = false;
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		};

	}

	public void run() {
		t1.start();
		t2.start();
		t3.start();
	}

	public static void main(String args[]) {
		TestOderThread t = new TestOderThread();
		for (int i = 0; i < 10; i++) {
			t = new TestOderThread();
			t.run();
			//如果有一个为真 的话 就代表没有全部完成。
			//采用繁忙等待模式
			while (t.x1 || t.x2 || t.x3) {
				if (!t.x1&&!t.x2&&!t.x3) {
					//代表全部完成
					//System.out.println();
				    break;
				}else{
					//break;
				}
			}
		}
	}
}