diff --git a/.idea/misc.xml b/.idea/misc.xml index be610f6..1c2e834 100644 --- a/.idea/misc.xml +++ b/.idea/misc.xml @@ -1,6 +1,6 @@ - + \ No newline at end of file diff --git a/.idea/modules.xml b/.idea/modules.xml index 4ea9f43..895aaa7 100644 --- a/.idea/modules.xml +++ b/.idea/modules.xml @@ -2,9 +2,9 @@ - + \ No newline at end of file diff --git a/Hello/.idea/uiDesigner.xml b/.idea/uiDesigner.xml similarity index 100% rename from Hello/.idea/uiDesigner.xml rename to .idea/uiDesigner.xml diff --git a/Hello/src/src/Hello.java b/Hello/src/src/Hello.java deleted file mode 100644 index 4211e90..0000000 --- a/Hello/src/src/Hello.java +++ /dev/null @@ -1,10 +0,0 @@ -public class Hello { - public static void main(String[] args) { - System.out.println("主方法"); - test("传值"); - - } - public static void test(String S) { - System.out.println(S); - } -} diff --git a/Hello/src/src/Main.java b/Hello/src/src/Main.java deleted file mode 100644 index 3e59c38..0000000 --- a/Hello/src/src/Main.java +++ /dev/null @@ -1,5 +0,0 @@ -public class Main { - public static void main(String[] args) { - System.out.println("Hello world!"); - } -} \ No newline at end of file diff --git a/Hello/.idea/.gitignore b/基础语法/.idea/.gitignore similarity index 100% rename from Hello/.idea/.gitignore rename to 基础语法/.idea/.gitignore diff --git a/Hello/.idea/code.iml b/基础语法/.idea/code.iml similarity index 100% rename from Hello/.idea/code.iml rename to 基础语法/.idea/code.iml diff --git a/Hello/.idea/misc.xml b/基础语法/.idea/misc.xml similarity index 100% rename from Hello/.idea/misc.xml rename to 基础语法/.idea/misc.xml diff --git a/Hello/.idea/modules.xml b/基础语法/.idea/modules.xml similarity index 100% rename from Hello/.idea/modules.xml rename to 基础语法/.idea/modules.xml diff --git a/Hello/out/production/code/.idea/uiDesigner.xml b/基础语法/.idea/uiDesigner.xml similarity index 100% rename from Hello/out/production/code/.idea/uiDesigner.xml rename to 基础语法/.idea/uiDesigner.xml diff --git a/Hello/out/production/code/.idea/.gitignore b/基础语法/out/production/code/.idea/.gitignore similarity index 100% rename from Hello/out/production/code/.idea/.gitignore rename to 基础语法/out/production/code/.idea/.gitignore diff --git a/Hello/out/production/code/.idea/code.iml b/基础语法/out/production/code/.idea/code.iml similarity index 100% rename from Hello/out/production/code/.idea/code.iml rename to 基础语法/out/production/code/.idea/code.iml diff --git a/Hello/out/production/code/.idea/misc.xml b/基础语法/out/production/code/.idea/misc.xml similarity index 100% rename from Hello/out/production/code/.idea/misc.xml rename to 基础语法/out/production/code/.idea/misc.xml diff --git a/Hello/out/production/code/.idea/modules.xml b/基础语法/out/production/code/.idea/modules.xml similarity index 100% rename from Hello/out/production/code/.idea/modules.xml rename to 基础语法/out/production/code/.idea/modules.xml diff --git a/基础语法/out/production/code/.idea/uiDesigner.xml b/基础语法/out/production/code/.idea/uiDesigner.xml new file mode 100644 index 0000000..2b63946 --- /dev/null +++ b/基础语法/out/production/code/.idea/uiDesigner.xml @@ -0,0 +1,124 @@ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + \ No newline at end of file diff --git a/Hello/out/production/code/Hello.class b/基础语法/out/production/code/Hello.class similarity index 100% rename from Hello/out/production/code/Hello.class rename to 基础语法/out/production/code/Hello.class diff --git a/Hello/out/production/src/Hello.class b/基础语法/out/production/src/Hello.class similarity index 100% rename from Hello/out/production/src/Hello.class rename to 基础语法/out/production/src/Hello.class diff --git a/Hello/out/production/src/Main.class b/基础语法/out/production/src/Main.class similarity index 100% rename from Hello/out/production/src/Main.class rename to 基础语法/out/production/src/Main.class diff --git a/Hello/src/.gitignore b/基础语法/src/.gitignore similarity index 100% rename from Hello/src/.gitignore rename to 基础语法/src/.gitignore diff --git a/Hello/src/src.iml b/基础语法/src/src.iml similarity index 100% rename from Hello/src/src.iml rename to 基础语法/src/src.iml diff --git a/基础语法/src/src/com/kuang/base/Demo02.java b/基础语法/src/src/com/kuang/base/Demo02.java new file mode 100644 index 0000000..9929b3c --- /dev/null +++ b/基础语法/src/src/com/kuang/base/Demo02.java @@ -0,0 +1,24 @@ +package com.kuang.base; + +public class Demo02 { + public static void main(String[] args) { +// 八大基本数据类型 +// 整数 + int num1 = 10;//最常用 + byte num2 = 20; + short num3 = 30; + long num4 = 1000;//Long类型要在数字后面加个L + +// 小数：浮点数 + float num5 = 50.1F;//float后面需要加F + double num6 = 3.1415926; + +// 字符类型 + char name = 'A'; +// 字符串类型，string不是关键字，类 + String name1 = "测试"; + boolean flag = true; + + + } +} diff --git a/基础语法/src/src/com/kuang/base/Demo03.java b/基础语法/src/src/com/kuang/base/Demo03.java new file mode 100644 index 0000000..9ef500f --- /dev/null +++ b/基础语法/src/src/com/kuang/base/Demo03.java @@ -0,0 +1,64 @@ +package com.kuang.base; + +public class Demo03 { + public static void main(String[] args) { +// 整数扩展: 进制 二进制0b 十进制 八进制0 十六进制0x + int i = 10; + int i2 = 010;//八进制 + int i3 = 0x10;//十六进制 + System.out.println(i); + System.out.println(i2); + System.out.println(i3); +// ================================ +// 浮点数扩展： 银行业务怎么表示 +// BigDecimal 数学工具类 + System.out.println(0.1 + 0.2);//0.30000000000000004 + System.out.println(0.1f + 0.2f);//0.3 +// ================================ +// float 有限 离散 舍入误差 大约 接近但不等于 +// double +// 最好完全避免使用浮点数进行比较 + float f = 0.1f; + double d = 1.0 / 10; + System.out.println(f == d);//false + +// ================================== +// 字符扩展 +// ================================== + char c1 = 'a'; + char c2 = '中'; + System.out.println(c1); + System.out.println((int) c1);//强制转换 + System.out.println(c2); + System.out.println((int) c2);//强制转换 +// 所有的字符本质还是数字 +// 编码 Unicode 表：97=a 65=A 48=0 +// U0000 UFFFF +// ================================== +// 转义字符 +// ================================== + System.out.println("Hello\nWorld");//换行 + System.out.println("Hello\tWorld");//制表符 + System.out.println("Helloooo\tWorld");//制表符 + System.out.println("Hello\rWorld");//回车 + System.out.println("Hello\bWorld");//退格 + System.out.println("Hello\"World\"");//双引号 + System.out.println("Hello\'World\'");//单引号 + String sa = new String("Hello"); + String sb = new String("Hello"); + System.out.println(sa == sb);//false + + String sc = "Hello"; + String sd = "Hello"; + System.out.println(sc == sd);//true +// ================================== +// 布尔值扩展 +// ================================== + boolean flag = true; + if (flag) { + System.out.println("真"); + } else { + System.out.println("假"); + } + } +} diff --git a/基础语法/src/src/com/kuang/base/Demo04.java b/基础语法/src/src/com/kuang/base/Demo04.java new file mode 100644 index 0000000..9173184 --- /dev/null +++ b/基础语法/src/src/com/kuang/base/Demo04.java @@ -0,0 +1,26 @@ +package com.kuang.base; + +public class Demo04 { + public static void main(String[] args) { + int i = 128; + byte b = (byte) i;//内存溢出 + +// 强制转换(类型)变量名 高->低 +// 自动转换 低->高 + System.out.println(i); + System.out.println(b); + /* + 注意点： + 1.不能对布尔值进行转换 + 2.不能把对象类型转换为不相干的类型 + 3.把高容量转换到低容量的时候，强制转换 + 4.转换的时候可能存在内存溢出，或者精度问题！ + */ + System.out.println((int) 23.7);//23 + char c = 'a'; + int d = c + 1; + System.out.println(d);//98 + System.out.println((char) d);//b + + } +} diff --git a/基础语法/src/src/com/kuang/base/Demo06.java b/基础语法/src/src/com/kuang/base/Demo06.java new file mode 100644 index 0000000..6668943 --- /dev/null +++ b/基础语法/src/src/com/kuang/base/Demo06.java @@ -0,0 +1,16 @@ +package com.kuang.base; + +public class Demo06 { + public static void main(String[] args) { +// 操作比较大的数的时候，注意溢出问题 +// jdk7新特性，数字之间可以用下划线分割 + int money = 10_0000_0000; + int years = 20; + int total = money * years;//-1474836480 + long total1 = money * years;//默认是int类型，转换之前已经存在问题了 + long total2 = money * (long) years;//先把一个因子变成long类型，整个表达式发生提升 + System.out.println(total);//-1474836480 + long tatal3 = money * ((long) years); + System.out.println(tatal3);//20000000000 + } +} diff --git a/基础语法/src/src/com/kuang/base/Demo07.java b/基础语法/src/src/com/kuang/base/Demo07.java new file mode 100644 index 0000000..b29ddad --- /dev/null +++ b/基础语法/src/src/com/kuang/base/Demo07.java @@ -0,0 +1,10 @@ +package com.kuang.base; + +public class Demo07 { + public static void main(String[] args) { + int a = 1, b = 2, c = 3, d = 4; + String name = "qinjiang"; + char x = 'X'; + double pi = 3.14; + } +} diff --git a/基础语法/src/src/com/kuang/base/Demo08.java b/基础语法/src/src/com/kuang/base/Demo08.java new file mode 100644 index 0000000..190a3cf --- /dev/null +++ b/基础语法/src/src/com/kuang/base/Demo08.java @@ -0,0 +1,28 @@ +package com.kuang.base; + +public class Demo08 { + // 属性：变量 +// 实例变量：从属于对象；如果不进行初始化，会有一个默认值 0 0.0 null +// 布尔值：默认是false +// 除了基本类型，其余的默认都是null + String name; + int age; + static double salary = 2500; + + // main方法 + public static void main(String[] args) { +// 局部变量；必须声明和初始化值 + int i = 10; + System.out.println(i); + Demo08 demo08 = new Demo08(); + System.out.println(demo08.age); + System.out.println(salary); +// 类变量：static + + } + + // 其他方法 + public void add() { + + } +} diff --git a/基础语法/src/src/com/kuang/base/Demo09.java b/基础语法/src/src/com/kuang/base/Demo09.java new file mode 100644 index 0000000..cfe7cdd --- /dev/null +++ b/基础语法/src/src/com/kuang/base/Demo09.java @@ -0,0 +1,11 @@ +package com.kuang.base; + +public class Demo09 { + // 修饰符不存在先后顺序 + final static double PI = 3.14; + + public static Number main(String[] args) { + System.out.println(PI); + return PI; + } +} diff --git a/基础语法/src/src/com/kuang/opertate/Demo01.java b/基础语法/src/src/com/kuang/opertate/Demo01.java new file mode 100644 index 0000000..ce6687c --- /dev/null +++ b/基础语法/src/src/com/kuang/opertate/Demo01.java @@ -0,0 +1,17 @@ +package com.kuang.opertate; + +public class Demo01 { + public static void main(String[] args) { +// 二元运算符 + int a = 10; + int b = 20; + int c = 30; + int d = 40; + System.out.println(a + b);//30 + System.out.println(a - b);//-10 + System.out.println(a * b);//200 + System.out.println(a / (double) b);//0 + + + } +} diff --git a/基础语法/src/src/com/kuang/opertate/Demo02.java b/基础语法/src/src/com/kuang/opertate/Demo02.java new file mode 100644 index 0000000..4704ac9 --- /dev/null +++ b/基础语法/src/src/com/kuang/opertate/Demo02.java @@ -0,0 +1,15 @@ +package com.kuang.opertate; + +public class Demo02 { + public static void main(String[] args) { + long a = 123123123123L; + int b = 123; + short c = 10; + byte d = 8; + System.out.println(a + b + c + d); + + int e = (int) a; + System.out.println(e); + + } +} diff --git a/基础语法/src/src/com/kuang/opertate/Demo03.java b/基础语法/src/src/com/kuang/opertate/Demo03.java new file mode 100644 index 0000000..0496e6c --- /dev/null +++ b/基础语法/src/src/com/kuang/opertate/Demo03.java @@ -0,0 +1,20 @@ +package com.kuang.opertate; + +public class Demo03 { + public static void main(String[] args) { +// 关系运算符返回的结果 + int flag = test(null); + System.out.println(flag); + } + + public static int test(String[] args) { + int a = 10; + int b = 20; + return a + b; + /* System.out.println(a > b); + System.out.println(a < b); + System.out.println(a == b); + System.out.println(a != b);*/ + + } +} diff --git a/基础语法/src/src/com/kuang/opertate/Demo04.java b/基础语法/src/src/com/kuang/opertate/Demo04.java new file mode 100644 index 0000000..d5515f2 --- /dev/null +++ b/基础语法/src/src/com/kuang/opertate/Demo04.java @@ -0,0 +1,15 @@ +package com.kuang.opertate; + +public class Demo04 { + public static void main(String[] args) { + int a = 3; + int b = a++;//先赋值后自增 + int c = ++a;//先自增后赋值 + System.out.println(a); + System.out.println(b); + System.out.println(c); +// 幂运算 2^3 很多运算 我们会使用一些工具类来操作 + double pow = Math.pow(2, 3); + System.out.println(pow); + } +} diff --git a/基础语法/src/src/com/kuang/opertate/Demo05.java b/基础语法/src/src/com/kuang/opertate/Demo05.java new file mode 100644 index 0000000..00b211d --- /dev/null +++ b/基础语法/src/src/com/kuang/opertate/Demo05.java @@ -0,0 +1,21 @@ +package com.kuang.opertate; + +//逻辑运算符 +public class Demo05 { + public static void main(String[] args) { +// 与 或 非 + int a = 10; + int b = 20; + int c = 30; + int d = 40; + System.out.println(a > b && c > d);//false + System.out.println(a > b || c > d);//false + System.out.println(!(a > b));//true +// 短路运算 + int e = 5; + boolean f = (e < 4) && (e++ < 4); + System.out.println(f);//false + System.out.println(e);//5 + + } +} diff --git a/基础语法/src/src/com/kuang/opertate/Demo06.java b/基础语法/src/src/com/kuang/opertate/Demo06.java new file mode 100644 index 0000000..8ec7ef2 --- /dev/null +++ b/基础语法/src/src/com/kuang/opertate/Demo06.java @@ -0,0 +1,20 @@ +package com.kuang.opertate; + +public class Demo06 { + public static void main(String[] args) { + /* + * A=0011 1100 + * B=0000 1101 + * A&B=0000 1100 + * A|B=0011 1101 + * A^B=0011 0001 + * ~B=1111 0010 + * 2*8=16 2*2*2*2=16 + * 效率极高 + * << *2 + * >> /2 + * + * */ + System.out.println(2 << 3);//16 + } +} diff --git a/基础语法/src/src/com/kuang/opertate/Demo07.java b/基础语法/src/src/com/kuang/opertate/Demo07.java new file mode 100644 index 0000000..67666be --- /dev/null +++ b/基础语法/src/src/com/kuang/opertate/Demo07.java @@ -0,0 +1,16 @@ +package com.kuang.opertate; + +public class Demo07 { + public static void main(String[] args) { + int a = 10; + int b = 20; + a += b;//a=a+b + a -= b;//a=a-b + System.out.println(a); +// 字符串连接符 + System.out.println(a + b); +// 字符串连接符 + System.out.println("" + a + b); + System.out.println(a + b + ""); + } +} diff --git a/基础语法/src/src/com/kuang/opertate/Demo08.java b/基础语法/src/src/com/kuang/opertate/Demo08.java new file mode 100644 index 0000000..b76722d --- /dev/null +++ b/基础语法/src/src/com/kuang/opertate/Demo08.java @@ -0,0 +1,16 @@ +package com.kuang.opertate; + +import com.kuang.base.Demo09; + +public class Demo08 { + public static void main(String[] args) { +// x?y:z +// 如果x==true，则结果为y，否则结果为z + int score = 80; + String type = score < 60 ? "不及格" : "及格"; +// System.out.println(type); + Demo09 demo09 = new Demo09(); + demo09.main(null); + + } +} diff --git a/Hello/Hello.iml b/基础语法/基础语法.iml similarity index 100% rename from Hello/Hello.iml rename to 基础语法/基础语法.iml