diff --git a/src/main/java/thead/thread_7/Run.java b/src/main/java/thead/thread_7/Run.java
new file mode 100644
index 0000000..7f50a38
--- /dev/null
+++ b/src/main/java/thead/thread_7/Run.java
@@ -0,0 +1,12 @@
+package thead.thread_7;
+
+public class Run {
+    public static void main(String[] args) {
+        Service service = new Service();
+        ThreadA threadA = new ThreadA(service);
+        threadA.start();
+
+        ThreadB threadB = new ThreadB(service);
+        threadB.start();
+    }
+}
diff --git a/src/main/java/thead/thread_7/Service.java b/src/main/java/thead/thread_7/Service.java
new file mode 100644
index 0000000..b499d35
--- /dev/null
+++ b/src/main/java/thead/thread_7/Service.java
@@ -0,0 +1,21 @@
+package thead.thread_7;
+
+public class Service {
+    public synchronized static void methodB() {
+        synchronized (Service.class) {
+            System.out.println("B方法开始");
+            System.out.println("B方法结束");
+        }
+    }
+
+    public void methodA() {
+        synchronized (this) {
+            System.out.println("A方法开始");
+            boolean b = true;
+            while (b) {
+
+            }
+            System.out.println("A方法结束");
+        }
+    }
+}
diff --git a/src/main/java/thead/thread_7/ThreadA.java b/src/main/java/thead/thread_7/ThreadA.java
new file mode 100644
index 0000000..d1e8b73
--- /dev/null
+++ b/src/main/java/thead/thread_7/ThreadA.java
@@ -0,0 +1,23 @@
+package thead.thread_7;
+
+public class ThreadA extends Thread {
+
+    public Service service;
+
+    /**
+     * Allocates a new {@code Thread} object. This constructor has the same
+     * effect as {@linkplain #Thread(ThreadGroup, Runnable, String) Thread}
+     * {@code (null, null, gname)}, where {@code gname} is a newly generated
+     * name. Automatically generated names are of the form
+     * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
+     */
+    public ThreadA(Service service) {
+        super.run();
+        this.service = service;
+    }
+
+    @Override
+    public void run() {
+        service.methodA();
+    }
+}
diff --git a/src/main/java/thead/thread_7/ThreadB.java b/src/main/java/thead/thread_7/ThreadB.java
new file mode 100644
index 0000000..2286a71
--- /dev/null
+++ b/src/main/java/thead/thread_7/ThreadB.java
@@ -0,0 +1,22 @@
+package thead.thread_7;
+
+public class ThreadB extends Thread {
+
+    private final Service service;
+
+    /**
+     * Allocates a new {@code Thread} object. This constructor has the same
+     * effect as {@linkplain #Thread(ThreadGroup, Runnable, String) Thread}
+     * {@code (null, null, gname)}, where {@code gname} is a newly generated
+     * name. Automatically generated names are of the form
+     * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
+     */
+    public ThreadB(Service service) {
+        this.service = service;
+    }
+
+    @Override
+    public void run() {
+        service.methodB();
+    }
+}