JAVA-day01（1-170）

一、基本的语法结构
- 0.编译方法
- 1.基本程序框架（01）
- 2.从用户界面接收输入信息的语法（03）
- 3.向用户界面输出文字（03）
- 4.if语句运行规则（03）
- 5.for循环运行规则（04）
- 6.while循环结构
- 7.dowhile循环结构
二、实例
- 1.基本程序框架
- 2.从用户界面接收输入信息的语法
- 5.for循环运行规则
总结

一、基本的语法结构

0.编译方法

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Windows+R调用dos系统

输入cmd

输入要运行文件的地址

输入javac Helloworld.java

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最后运行

输入java Helloworld

1.基本程序框架（01）

public class HelloWorld{public static void main(String[] args){System.out.println("Hello World!");}
}

2.从用户界面接收输入信息的语法（03）

java.util.Scanner s=new java.util.Scanner(System.in);
int a=s.nextInt();

3.向用户界面输出文字（03）

System.out.println("欢迎使用本系统！")
System.out.println("请输入指令：")

注释：实例与上题同。

4.if语句运行规则（03）

if(weather==1){//下雨天System.out.println("下雨天");}else if(weather==0){//晴天System.out.println("晴天");}

注释：实例与上题同。

5.for循环运行规则（04）

for（int i=1;i<=10;i+=1）{System.out.println(i);
}for（int i=1;i<=10;i++）{System.out.println(i);
}for（int i=1;i<=10;i=i+1）{System.out.println(i);
}

6.while循环结构

while(布尔表达式){循环体；
}

7.dowhile循环结构

do{循环体；
}while(布尔表达式);

二、实例

1.基本程序框架

public class HelloWorld{public static void main(String[] args){System.out.println("Hello World!");}
}

2.从用户界面接收输入信息的语法

public class IfTest
{public static void main(String[] args){java.util.Scanner s=new java.util.Scanner(System.in);System.out.println("欢迎使用本系统，您通过本系统可以完成一些简单的判断");System.out.println("说明1:1表示下雨，0表示晴天");System.out.println("说明2:1表示男，0表示女");System.out.println("说明3:温度为数字");//接收性别System.out.print("请输入性别：");int sex=s.nextInt();//接收天气的状况System.out.print("请输入当前天气状况：");int weather=s.nextInt();if(weather==1){//下雨天//System.out.println("下雨天");if(sex==1){System.out.println("带一把大黑伞");}else if(sex==0){System.out.println("带一把小花伞");}else{System.out.println("对不起，您的性别是怎么回事？");}}else if(weather==0){//晴天//System.out.println("晴天");int tem=s.nextInt();if(tem>30){if(sex==1){System.out.println("戴墨镜");}else if(sex==0){System.out.println("擦防晒霜");}else{System.out.println("对不起，您的性别是怎么回事？");}}else{System.out.println("对不起，您输入的天气状况不存在！");}}}
}

注解：其中，s为输入信息的句段名称，a为输入信息在程序中的名称。两次输入都可以用s作为名称。

5.for循环运行规则

public class ForTest
{public static void main(String[] args){for(int i=0;i<10;i++){System.out.println("i--->"+i);}System.out.println(i);}
}

或者写为如下形式：

public class ForTest
{public static void main(String[] args){int i;for(i=0;i<10;i++){System.out.println("i--->"+i);}System.out.println(i);}
}

总结

提示：这里对文章进行总结：
这是第一次对java学习所做的笔记。希望学习不辍，进步不止。

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