在某些情况下,我们需要等待线程的终结。例如,我们可能会遇到程序在执行前需要初始化资源。在执行剩下的代码之前,我们需要等待线程完成初始化任务。为达此目的, 我们使用Thread 类的join() 方法。当前线程调用某个线程的这个方法时,它会暂停当前线程,直到被调用线程执行完成。
DataSourcesLoader.java
public class DataSourcesLoader implements Runnable { @Override public void run() { System.out.println("DataSourcesLoader.run start"); try { TimeUnit.SECONDS.sleep(5); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("DataSourcesLoader.run end"); } }
NetworkConnectionsLoader.java
public class NetworkConnectionsLoader implements Runnable { @Override public void run() { System.out.println("NetworkConnectionsLoader.run start"); try { TimeUnit.SECONDS.sleep(2); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("NetworkConnectionsLoader.run end"); } }
Test.java
public class Test { public static void main(String[] args) { Thread thread1 = new Thread(new DataSourcesLoader()); Thread thread2 = new Thread(new NetworkConnectionsLoader()); thread1.start(); thread2.start(); try { thread1.join(); thread2.join(); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("Test.main"); } }
打印结果
DataSourcesLoader.run start NetworkConnectionsLoader.run start NetworkConnectionsLoader.run end DataSourcesLoader.run end Test.main Process finished with exit code 0