概率比显著水平小，就是小概率事件发生吗

老师，连接不上网络?

请问老师，以下两种把String 转换为int的方法有什么区别，应用场景有什么区分？

Integer i3 = Integer.valueOf("123");

Integer i4 = Integer.parseInt("123");

这个图片全面一点 老师这个怎么解决呢

41岁小白，初中毕业，感觉像是在看天书，而且视频看完了也问不出什么问题来。越来越晕了。

老师好，为什么total后面加上1或2后，变量total1和total2表示的含义仍然与total相同，这1、2到底表示什么含义呢？

/**
 * 计算100之内的累加和，所有奇数和，所有偶数和
 */
public class Sum200 {
    public static void main(String[] args) {
        int sum=0;
        int oddSum=0;
        int eveSum=0;
        for (int i=0;i<=200;i++){
            sum+=i;
        if (i%2==0){
            oddSum+=i;
        }else {
            eveSum+=i;
        }
        }
        System.out.println("总和"+sum);
        System.out.println("奇数和"+oddSum);
        System.out.println("偶数和"+eveSum);

        int a=0;
        int sum1=0;
        int oddSum1=0;
        int eveSum1=0;
        while (a<=200){
            a++;
            sum1+=a;
        if (a%2==0){
            eveSum1+=a;
        }else {
            oddSum1+=a;
        }
        }
        System.out.println("总和"+sum1);
        System.out.println("奇数和"+oddSum1);
        System.out.println("偶数和"+eveSum1);

    }
}

两种方法的结果不一样，后面这个是不是写错

"C:\Program Files\Java\jdk-16.0.1\bin\java.exe" "-javaagent:F:\IntelliJ IDEA 2021.3\lib\idea_rt.jar=59331:F:\IntelliJ IDEA 2021.3\bin" -Dfile.encoding=UTF-8 -classpath F:\校园卡管理系统\demo1\springjdbcdemo\out\production\springjdbcdemo;D:\百战程序员java\SSM框架和项目开发\Spring\软件\lib\commons-logging-1.2.jar;D:\百战程序员java\SSM框架和项目开发\Spring\软件\lib\spring-tx-5.2.7.RELEASE.jar;D:\百战程序员java\SSM框架和项目开发\Spring\软件\lib\spring-core-5.2.7.RELEASE.jar;D:\百战程序员java\SSM框架和项目开发\Spring\软件\lib\spring-jdbc-5.2.7.RELEASE.jar;D:\百战程序员java\SSM框架和项目开发\Spring\软件\lib\spring-beans-5.2.7.RELEASE.jar;D:\百战程序员java\SSM框架和项目开发\Spring\软件\lib\mysql-connector-java-5.1.48.jar;D:\百战程序员java\SSM框架和项目开发\Spring\软件\lib\spring-context-5.2.7.RELEASE.jar;D:\百战程序员java\SSM框架和项目开发\Spring\软件\lib\spring-expression-5.2.7.RELEASE.jar com.bjsxt.test.addUsersTest

Wed Jan 19 14:41:22 CST 2022 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

Exception in thread "main" org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 237 milliseconds ago.  The last packet sent successfully to the server was 224 milliseconds ago.

at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:82)

at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:612)

at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:862)

at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:917)

at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:927)

at com.bjsxt.dao.impl.UsersDaoImpl.insertUsers(UsersDaoImpl.java:30)

at com.bjsxt.service.impl.UsersServiceImpl.addUsers(UsersServiceImpl.java:25)

at com.bjsxt.test.addUsersTest.main(addUsersTest.java:15)

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 237 milliseconds ago.  The last packet sent successfully to the server was 224 milliseconds ago.

at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:78)

at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)

at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)

at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:990)

at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:201)

at com.mysql.jdbc.MysqlIO.negotiateSSLConnection(MysqlIO.java:4869)

at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1656)

at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1217)

at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2189)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2220)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2015)

at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:768)

at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)

at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:78)

at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)

at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:385)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:323)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:189)

at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:155)

at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriver(DriverManagerDataSource.java:146)

at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnectionFromDriver(AbstractDriverBasedDataSource.java:205)

at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnection(AbstractDriverBasedDataSource.java:169)

at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:158)

at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:116)

at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79)

... 7 more

Caused by: javax.net.ssl.SSLHandshakeException: No appropriate protocol (protocol is disabled or cipher suites are inappropriate)

at java.base/sun.security.ssl.HandshakeContext.<init>(HandshakeContext.java:172)

at java.base/sun.security.ssl.ClientHandshakeContext.<init>(ClientHandshakeContext.java:98)

at java.base/sun.security.ssl.TransportContext.kickstart(TransportContext.java:238)

at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:434)

at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:412)

at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:186)

老师我想问一下出现这个异常怎么解决呀 我找了好久没找到问题....

一定要是这样吗

这样的输出结果是正确的，但是，这样为什么不行

这个运行结构是这样的

老师没有文档看，麻烦看看能不能找一下，谢谢你

对着视频敲的，这哪里出错了啊？检查好久都没发现

我方坦克时，游戏界面停止了，并没有出现爆炸效果！

pygametimerandom
pygame.sprite Sprite

SCREEN_WIDTH SCREEN_HEIGHT BG_COLOR pygame.TEXT_COLOR pygame.BaseItemSpritepygame.sprite.Sprite.MainGamewindow my_tank enemyTankList enemyTankCount myBulletList enemyBulletList explodeList pygame.display.MainGame.window pygame.display.SCREEN_WIDTHSCREEN_HEIGHTMainGame.my_tank Tank.pygame.display.time.MainGame.window.BG_COLOR.MainGame.window..MainGame.enemyTankListMainGame.my_tank MainGame.my_tank.liveMainGame.my_tank.MainGame.my_tank
                MainGame.my_tank ....MainGame.my_tank MainGame.my_tank.liveMainGame.my_tank.stopMainGame.my_tank.pygame.display.top i MainGame.enemyTankCountleft random.speed random.enemy EnemyTanklefttopspeedMainGame.enemyTankList.enemyexplode MainGame.explodeListexplode.liveexplode.MainGame.explodeList.explodeenemyTank MainGame.enemyTankListenemyTank.liveenemyTank.enemyTank.enemyBullet enemyTank.enemyBulletMainGame.enemyBulletList.enemyBulletMainGame.enemyTankList.enemyTankmyBullet MainGame.myBulletListmyBullet.livemyBullet.myBullet.myBullet.MainGame.myBulletList.myBulletenemyBullet MainGame.enemyBulletListenemyBullet.liveenemyBullet.enemyBullet.enemyBullet.MainGame.enemyBulletList.enemyBulletpygame.font.font pygame.font.textSurface font.TEXT_COLORtextSurface

    eventList pygame.event.event eventListevent.type pygame.QUIT.event.type pygame.KEYDOWNMainGame.my_tank MainGame.my_tank.liveevent.key pygame.K_LEFTMainGame.my_tank.direction MainGame.my_tank.stop event.key pygame.K_RIGHTMainGame.my_tank.direction MainGame.my_tank.stop event.key pygame.K_UPMainGame.my_tank.direction MainGame.my_tank.stop event.key pygame.K_DOWNMainGame.my_tank.direction MainGame.my_tank.stop event.key pygame.K_SPACEMainGame.myBulletListmyBullet BulletMainGame.my_tankMainGame.myBulletList.myBulletevent.type pygame.KEYUPevent.key pygame.K_UP pygame.K_DOWN event.key pygame.K_LEFT event.key pygame.K_RIGHTMainGame.my_tank MainGame.my_tank.liveMainGame.my_tank.stop TankBaseItem.images pygame.image.pygame.image.pygame.image.pygame.image..direction .image .images.direction.rect .image..rect.left .rect.top .speed .stop .live .direction .rect.left .rect.left .speed
        .direction .rect.top .rect.top .speed
        .direction .rect.top .rect.height SCREEN_HEIGHT.rect.top .speed
        .direction .rect.left .rect.height SCREEN_WIDTH.rect.left .speed

    Bullet.image .images.directionMainGame.window..image.rectMyTankTankEnemyTankTankEnemyTank..images pygame.image.pygame.image.pygame.image.pygame.image..direction ..image .images.direction.rect .image..rect.left .rect.top .speed .flag .step num random.num num num num .step .direction ..step ..step num random.num BulletBulletBaseItem.image pygame.image..direction .direction
        .rect .image..direction .rect.left .rect.left .rect.width.rect.width.rect.top .rect.top .rect.height
        .direction .rect.left .rect.left .rect.width.rect.width.rect.top .rect.top .rect.height
        .direction .rect.left .rect.left .rect.width.rect.width.rect.top .rect.top .rect.width.rect.width.direction .rect.left .rect.left .rect.width
            .rect.top .rect.top .rect.width.rect.width.speed .live .direction .rect.top .rect.top .speed
            .live .direction .rect.left .rect.width SCREEN_WIDTH.rect.left .speed
            .live .direction .rect.top .rect.height SCREEN_HEIGHT.rect.top .speed
            .live .direction .rect.left .rect.left .speed
            .live MainGame.window..image.rectenemyTank MainGame.enemyTankListpygame.sprite.enemyTankenemyTank.live .live explode ExplodeenemyTankMainGame.explodeList.explodeMainGame.my_tank MainGame.my_tank.livepygame.sprite.MainGame.my_tankexplode ExplodeMainGame.my_tankMainGame.explodeList.explode.live MainGame.my_tank.live WallExplode.rect .rect
        .images pygame.image.pygame.image.pygame.image.pygame.image.pygame.image..step .image .images.step.live .step .images.image .images.step.step MainGame.window..image.rect.live .step Music__name__ MainGame.

为什么properties文件路径一定要在src下，换个路径就会报空指针异常

老师，这节的讲义能否提供下，资料里只有代码