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feat:[Java 断言 Assert 使用教程与最佳实践](https://www.wdbyte.com/java/assert/)
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‎README.md‎

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- [Java 集合框架](https://www.wdbyte.com/java/collection/)
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- [Java 中使用 List ](https://www.wdbyte.com/java/list/)
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### 代码测试
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- [Java 断言 Assert 使用教程与最佳实践](https://www.wdbyte.com/java/assert/)
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## 😃Java I/O 教程
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- [Java 创建和写入文件](https://www.wdbyte.com/java/io/file-create-write/)

‎core-java-modules/core-java-base/README.md‎

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- [Java 枚举](https://www.wdbyte.com/java/enum/)
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- [Java 注释](*https://www.wdbyte.com/java/comment/*)
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- [Java 集合框架](https://www.wdbyte.com/java/collection/)
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- [Java 中使用 List ](https://www.wdbyte.com/java/list/)
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- [Java 中使用 List ](https://www.wdbyte.com/java/list/)
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- [Java 断言 Assert 使用教程与最佳实践](https://www.wdbyte.com/java/assert/)

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/assert1/AssertDemo1.java‎

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package com.wdbyte.assert1;
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import java.util.Arrays;
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import java.util.List;
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/**
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* @author niulang
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* @date 2024/04/22
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*/
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public class AssertDemo1 {
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public static void main(String[] args) {
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List<String> list = Arrays.asList("1", "2");
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boolean result = list.remove("x");
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//assert result;
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assert result : "移除失败";
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System.out.println(calc(100, 10));
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// 手动开启断言
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//ClassLoader.getSystemClassLoader().setDefaultAssertionStatus(true);
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//System.out.println(calc(100, 0));
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}
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public static int calc(int a, int b) {
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assert b != 0 : "除数不能为0";
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return a / b;
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/assert1/AssertDemo2.java‎

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package com.wdbyte.assert1;
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import java.util.Arrays;
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import java.util.List;
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import static com.google.common.base.Verify.*;
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/**
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* @author niulang
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* @date 2024/04/22
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*/
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public class AssertDemo2 {
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public static void main(String[] args) {
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int x = 100;
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verifyNotNull(x != 0);
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System.out.println(calc(100, 10));
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System.out.println(calc(100, 0));
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}
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public static int calc(int a, int b) {
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verify(b != 0, "除数不能为0");
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return a / b;
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/assert1/AssertDemo3.java‎

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package com.wdbyte.assert1;
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import java.util.Arrays;
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import java.util.List;
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/**
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* @author niulang
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* @date 2024/04/22
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*/
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public class AssertDemo3 {
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static final boolean asserts = false; // 设置为 false 来消除断言
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public static void main(String[] args) {
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List<String> list = Arrays.asList("1", "2");
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boolean result = list.remove("x");
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if (asserts) {
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assert result : "移除失败";
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}
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/assert1/AssertDemo4.java‎

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package com.wdbyte.assert1;
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import java.util.Arrays;
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import java.util.List;
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/**
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* @author niulang
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* @date 2024/04/22
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*/
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public class AssertDemo4 {
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static {
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boolean assertsEnabled = false;
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assert assertsEnabled = true; // 故意产生副作用！！！
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if (!assertsEnabled) {
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throw new RuntimeException("必须启用断言!!!");
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}
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}
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public static void main(String[] args) {
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List<String> list = Arrays.asList("1", "2");
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boolean result = list.remove("x");
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assert result : "移除失败";
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/assert1/AssertDemo5.java‎

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package com.wdbyte.assert1;
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import java.util.Arrays;
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import java.util.List;
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import com.google.common.base.Preconditions;
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import com.google.common.base.Verify;
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import org.apache.commons.lang3.Validate;
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import org.junit.jupiter.api.Assertions;
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/**
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* @author niulang
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* @date 2024/04/22
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*/
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public class AssertDemo5 {
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public static void main(String[] args) {
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List<String> list = Arrays.asList("1", "2");
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boolean result = list.remove("x");
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Assertions.assertTrue(result);
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Preconditions.checkNotNull("","msg");
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Validate.isTrue(list.isEmpty(),"msg");
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Verify.verify(list.isEmpty(),"msg");
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/assert1/InitializationDemo.java‎

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package com.wdbyte.assert1;
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public class InitializationDemo {
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static {
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init();
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}
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static void init() {
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System.out.println("Static initialization block called");
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// 假设这里有一个重要的初始化逻辑
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// 这个方法错误地在静态初始化之前被调用了
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assert isProperlyInitialized() : "System not properly initialized";
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}
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static boolean isProperlyInitialized() {
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// 这里返回 false 模拟系统未被正确初始化
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return false;
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}
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public InitializationDemo() {
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System.out.println("Constructor called");
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}
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public static void main(String[] args) {
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new InitializationDemo();
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/enum2/WeekdayTest.java‎

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System.out.println("Today is Monday.");
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}
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Weekday[] weekdays = Weekday.values();
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for (Weekday weekday : weekdays) {
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System.out.println(weekday);

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/thread/CompletableFutureTest.java‎

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package com.wdbyte.thread;
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import java.util.concurrent.CompletableFuture;
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import java.util.concurrent.Future;
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import org.junit.jupiter.api.Test;
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/**
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* @author niulang
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* @date 2023/11/01
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*/
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public class CompletableFutureTest {
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/**
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* 异步执行程序后，对正常响应和异常响应进行处理
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*/
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@Test
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public void completableFutureTest1() {
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CompletableFuture<Integer> completableFuture1 = CompletableFuture.supplyAsync(() -> {
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sleep(2000);
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System.out.println("do.....");
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return 1;
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});
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completableFuture1.thenAccept(res -> {
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System.out.println("收到结果：" + res
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);
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});
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System.out.println("等待");
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sleep(10 * 1000);
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}
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@Test
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public void completableFutureTest2() {
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CompletableFuture<Integer> completableFuture2 = CompletableFuture.supplyAsync(() -> {
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sleep(2000);
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System.out.println("do2.....");
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return 10 / 0;
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});
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completableFuture2.exceptionally(except -> {
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System.out.println("发生异常：" + except.getMessage());
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return 0;
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});
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System.out.println("等待");
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sleep(10 * 1000);
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}
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@Test
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public void completableFutureTest3() {
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CompletableFuture<Integer> completableFuture1 = CompletableFuture.supplyAsync(() -> {
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sleep(2000);
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System.out.println("do.....");
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return 1;
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});
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completableFuture1.thenAccept(res -> {
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System.out.println("收到结果：" + res
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);
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});
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System.out.println("等待");
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sleep(10 * 1000);
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}
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void sleep(long millis){
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try {
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Thread.sleep(millis);
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} catch (InterruptedException e) {
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throw new RuntimeException(e);
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}
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}
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}

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