【java】:多線程面試題
阿新 • • 發佈：2017-05-28
編寫 cond func condition pri ide syn ack rri
經常面試的時候，讓寫各種亂七八糟的多線程面試題，收集了很多，有些還是挺好玩的。
1、編寫程序實現,子線程循環10次,接著主線程循環20次,接著再子線程循環10次,主線程循環20次,如此反復,循環50次.
package com.zhikui.interview; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; /**@autor http://www.cnblogs.com/fingerboy/p/5352880.htmlView Code* @method 編寫程序實現,子線程循環10次,接著主線程循環20次,接著再子線程循環10次,主線程循環20次,如此反復,循環50次. */ public class interviewTest1{ public static void main(String[] args) { final Function fc= new Function(); //子線程 new Thread(new Runnable() { @Override public voidrun() { for(int i =0;i<50;i++){ fc.sub(); } } }).start(); //主線程 for(int i =0;i<50;i++){ fc.main(); } } } class Function { private boolean flag = false; //Lock lock=new ReentrantLock();// Condition con=lock.newCondition(); //子線程實現 public synchronized void sub(){ while(flag){ try { this.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } for(int i =0;i<10;i++){ System.out.println("[sub]"+i); } flag = true; this.notify(); } //主線程實現 public synchronized void main(){ while(!flag){ try { this.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } for(int i =0;i<20;i++){ System.out.println("[main]"+i); } flag = false; this.notify(); } }
2、設計四個線程,其中兩個線程每次對變量i加1,另外兩個線程每次對i減1.
package com.zhikui.interview; /** * @methord設計四個線程,其中兩個線程每次對變量i加1,另外兩個線程每次對i減1. * @author http://www.cnblogs.com/fingerboy/p/5352880.html * */ public class interviewTest2 { private int i = 0; public static void main(String[] args) { //執行線程 interviewTest2 it = new interviewTest2(); Add add = it.new Add(); Sub sub = it.new Sub(); for(int i=1;i<=2;i++){ new Thread(add,"線程"+i).start(); new Thread(sub,"線程"+i).start(); } } class Add implements Runnable { @Override public void run() { for(int j=0;j<10;j++){ addOne(); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } } class Sub implements Runnable{ @Override public void run() { for(int j=0;j<10;j++){ subOne(); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } } public synchronized void addOne(){ i++; System.out.println(Thread.currentThread().getName()+"[加一的值為]"+i); } public synchronized void subOne(){ i--; System.out.println(Thread.currentThread().getName()+"[減一的值為]"+i); } }View Code
3、T2 T3三個線程，怎樣保證T2在T1執行完之後執行 T3在T2執行完之後執行
package com.zhikui.interview; /** * @methor現在有T1 T2 T3三個線程，怎樣保證T2在T1執行完之後執行 T3在T2執行完之後執行 * @author http://blog.csdn.net/caohaicheng/article/details/38071097 * */ public class interviewTest3 { public static void main(String[] args) { interviewTest3 it = new interviewTest3(); T1 t1 = it.new T1("t1"); T1 t2 = it.new T1("t2"); T1 t3 = it.new T1("t3"); t1.start(); try { t1.join(); } catch (Exception e) { e.printStackTrace(); } t2.start(); try { t2.join(); } catch (Exception e) { e.printStackTrace(); } t3.start(); try { t3.join(); } catch (Exception e) { e.printStackTrace(); } } class T1 extends Thread{ private String name; public T1(String name){ this.name = name; } @Override public void run(){ for(int i=0;i<5;i++){ try { sleep(5); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(this.name+"循環"+i); } } } class T2 extends Thread{ private String name; public T2(String name){ this.name = name; } @Override public void run(){ for(int i=0;i<5;i++){ try { sleep(5); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(this.name+"循環"+i); } } } class T3 extends Thread{ private String name; public T3(String name){ this.name = name; } @Override public void run(){ for(int i=0;i<5;i++){ try { sleep(5); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(this.name+"循環"+i); } } } }View Code
4、寫一個死鎖的例子
package com.zhikui.interview; /** * 寫一個死鎖的例子 * @author author */ public class interviewTest4 { private static Object A = new Object(); private static Object B = new Object(); public static void main(String[] args) { //第一個線程 new Thread(new Runnable() { @Override public void run() { while(true){ synchronized (A) { synchronized (B) { System.out.println("死鎖A"); } } } } },"T1").start(); //第二個線程 new Thread(new Runnable() { @Override public void run() { while(true){ synchronized (B) { synchronized (A) { System.out.println("死鎖B"); } } } } },"T1").start(); } }View Code
5、兩個線程，一個線程輸出1，一個線程輸出2，循環輸出
package com.zhikui.interview; /** * @methor兩個線程，一個線程輸出1，一個線程輸出2，循環輸出 * @author http://blog.csdn.net/fufengrui/article/details/30232603 * */ public class interviewTest5 { public static void main(String[] args) { OneThread one = new OneThread(); TwoThread two = new TwoThread(); one.start(); two.start(); } } class OneThread extends Thread { @Override public void run() { synchronized (interviewTest5.class) { while (true) { System.out.println("1"); try { interviewTest5.class.wait(); } catch (InterruptedException e) { e.printStackTrace(); } interviewTest5.class.notify(); } } } } class TwoThread extends Thread { @Override public void run() { synchronized (interviewTest5.class) { while (true) { System.out.println("2"); interviewTest5.class.notify(); try { interviewTest5.class.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } } } }View Code
6、有1-26個數字和a-z字母,用Java多線程實現先輸出2和數字再輸出2個字母
package com.zhikui.interview; /** * 有1-26個數字和a-z字母,用Java多線程實現先輸出2和數字再輸出2個字母 * * @author https://zhidao.baidu.com/question/201633880.html * */ public class interviewTest6 { public static void main(String[] args) { Print p = new Print(); new numThread(p).start(); new charThread(p).start(); } } class Print { boolean boo = true; char ch = ‘A‘; int num = 1; public synchronized void printNum() { if (boo) { try { wait(); } catch (Exception e) { } System.out.print(num++); System.out.print(num++); } boo = false; notify(); if (num == 52) num++; } public synchronized void printChar() { if (!boo) { try { wait(); } catch (Exception e) { } System.out.print(ch++); System.out.print(ch++); } boo = true; notify(); } } class numThread extends Thread { Print p = null; public numThread(Print p) { this.p = p; } public void run() { while (p.num <= 53) p.printNum(); } } class charThread extends Thread { Print p = null; public charThread(Print p) { this.p = p; } public void run() { while (p.ch <= ‘Z‘) p.printChar(); } }View Code
【java】:多線程面試題