#feat:leetcode p1114题题解

src/leetcode/p1114/Foo.java

@@ -0,0 +1,76 @@
+package leetcode.p1114;
+
+/**
+ * @ProjectName: LeetCode
+ * @FileName: Foo
+ * @Author: 杨逸
+ * @Data:2026/3/25 19:24
+ * @Description: https://leetcode.cn/problems/print-in-order/description/
+ * 1114. 按序打印
+ */
+public class Foo {
+    /**
+     * 加锁和添加执行屏障解法
+     */
+    private boolean firstFinished = false;
+    private boolean secondFinished = false;
+    public Foo() {
+    }
+
+    public void first(Runnable printFirst) throws InterruptedException {
+        synchronized (this){
+            printFirst.run();
+            firstFinished = true;
+            notifyAll();
+        }
+    }
+
+    public void second(Runnable printSecond) throws InterruptedException {
+        synchronized (this){
+            while (!firstFinished){wait();}
+            printSecond.run();
+            secondFinished = true;
+            notifyAll();
+        }
+    }
+
+    public void third(Runnable printThird) throws InterruptedException {
+        synchronized (this){
+            while (!secondFinished)wait();
+            printThird.run();
+            notifyAll();
+        }
+    }
+}
+
+/**
+ * 使用volatile关键字实现线程可见性
+ * @author 杨逸
+ * @date 2026/03/25 19:35:21
+ */
+class VolatileSolution{
+    private volatile int flag;
+    public VolatileSolution() {
+        flag = 1;
+    }
+
+    public void first(Runnable printFirst) throws InterruptedException {
+        while (flag!=1){}
+        // printFirst.run() outputs "first". Do not change or remove this line.
+        printFirst.run();
+        flag = 2;
+    }
+
+    public void second(Runnable printSecond) throws InterruptedException {
+        while (flag!=2){}
+        // printSecond.run() outputs "second". Do not change or remove this line.
+        printSecond.run();
+        flag = 3;
+    }
+
+    public void third(Runnable printThird) throws InterruptedException {
+        while (flag!=3){}
+        // printThird.run() outputs "third". Do not change or remove this line.
+        printThird.run();
+    }
+}

src/leetcode/p1114/FooTest.java

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+package leetcode.p1114;
+
+import org.junit.Test;
+
+/**
+ * @ProjectName: LeetCode
+ * @FileName: FooTest
+ * @Author: 杨逸
+ * @Data:2026/3/25 20:03
+ * @Description:
+ */
+public class FooTest {
+
+    @Test(timeout = 1000L)
+    public void test() throws InterruptedException {
+        Foo foo = new Foo();
+        new Thread(()->{
+            try {
+                foo.third(() -> System.out.println("third"));
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }).start();
+        new Thread(()->{
+            try {
+                foo.second(() -> System.out.println("second"));
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }).start();
+        new Thread(()->{
+            try {
+                foo.first(() -> System.out.println("first"));
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }).start();
+    }
+}