update

oj/concurrent/TestJoin.java

@@ -0,0 +1,33 @@
+public class TestJoin {
+    public static void main(String[] args) {
+        TestJoinA a = new TestJoinA();
+        TestJoinB b = new TestJoinB(a);
+        b.start();
+        a.start();
+    }
+}
+
+class TestJoinA extends Thread {
+    @Override
+    public void run() {
+        System.out.println("A");
+    }
+}
+
+class TestJoinB extends Thread {
+    private TestJoinA a;
+
+    public TestJoinB(TestJoinA a) {
+        this.a = a;
+    }
+
+    @Override
+    public void run() {
+        try {
+            a.join();
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        System.out.println("B");
+    }
+}