0615

src/main/java/com/sf/day02/Test1.java

@@ -127,12 +127,17 @@ public class Test1 {
          *  b && a  == F
          *  a || b ==  T
          */
-        int x = 1;
-        int y = 1;
-        if(x++ == 2 && ++y ==2){
-            x = 7;
-        }
-        System.out.println(x);
-        System.out.println(y);
+//        int x = 1;
+//        int y = 1;
+//        int z = 1;
+//        if(x++ == 2 && ++y ==2){
+//            x = 7;
+//        }
+//        System.out.println(x);
+//        System.out.println(y);
+//        System.out.println(z);
+        int i =  10;
+        i  = i++;
+        System.out.println(i);
     }
 }

src/main/java/com/sf/day03/Test.java

@@ -0,0 +1,44 @@
+package com.sf.day03;
+
+public class Test {
+    @org.junit.Test
+    public void t1(){
+        int i = 1;
+        i *= 0.2;
+        i++;
+        System.out.println(i);  // 1
+    }
+
+    @org.junit.Test
+    public void t2(){
+        int i = 2;
+        i *= i++;
+        int j = 2;
+        j *= j+1;
+        int k = 2;
+        k *= ++k;
+        System.out.println("i=" + i);  // i = 4
+        System.out.println("j=" + j);  //  j  = 6
+        System.out.println("k=" + k);  //  k  = 6
+    }
+
+    @org.junit.Test
+    public void t3(){
+        int a = 8;
+        int b = 3;
+        //    8  >>>  3    8  /  2 的3次方
+        System.out.println(a>>>b);    //1
+
+        /**
+         *   0000 0001
+         *   0000 0010
+         *  |  0000 0011   //3
+         *  &  0000 0000
+         */
+        System.out.println(a>>>b  |  2);  //3
+        System.out.println(a>>>b  &  2);  //
+        //  位操作    x   左移  2<<3      8<1
+
+
+    }
+}

src/main/java/com/sf/day03/Test2.java

@@ -0,0 +1,212 @@
+package com.sf.day03;
+
+import org.junit.Test;
+
+public class Test2 {
+
+    @Test
+    public void t1(){
+        int age = 18;
+        if(age >= 18){
+            System.out.println("成年人");
+        }
+        if(age < 18){
+            System.out.println("未成年人");
+        }
+
+        if(age >= 18){
+            System.out.println("成年人");
+        }else {
+            System.out.println("未成年人");
+        }
+
+        if (age >=18) {
+            System.out.println("成年");
+        }else if(age<18  && age>=16){
+            System.out.println("ban");
+        }else {
+            System.out.println("未成年");
+        }
+    }
+
+    @Test
+    public void t2(){
+        String season = "summer1";
+        switch (season){
+            case "spring":
+                System.out.println("春天");
+                break;
+            case "summer":
+                System.out.println("夏天");
+                break;
+            case "autumn":
+                System.out.println("秋天");
+                break;
+            case "winter":
+                System.out.println("冬天");
+                break;
+            default:
+                System.out.println("输入有误");
+//                break;
+        }
+     }
+
+
+     @Test
+     public void t3(){
+        int sum = 0;
+        for (int i = 1; i<=100;i++){
+            sum += i;
+        }
+         System.out.println(sum);
+     }
+
+    /**
+     * 遍历1-100以内的偶数，并获取偶数的个数，获取所有的偶数的和
+     */
+    @Test
+     public void t4(){
+        int count = 0;
+        int sum = 0;
+        for (int i = 1;i<=100;i++){
+            if(i % 2 ==0){
+                System.out.println("偶数 == "+i);
+                count++;
+                sum += i;
+            }
+        }
+        System.out.println("偶数的个数 = "+count);
+        System.out.println("偶数总和 = "+sum);
+     }
+
+    /**
+     * 输出1000以内所有的水仙花数，所谓水仙花数是指一个3位数，其各个位上数字立方和等于其本身。
+     */
+    @Test
+     public void t5(){
+        int count = 0;
+        //itar
+        for (int i = 100; i < 1000; i++) {
+            //获取一个数的百位  十位  各位
+            int BW = i/100;
+            int SW = i / 10 % 10;
+            int GW = i % 10;
+            if(BW * BW * BW + SW * SW * SW + GW * GW * GW == i){
+                count++;
+                System.out.println(i);
+            }
+        }
+     }
+
+    /**
+     * 说明：输入两个正整数m和n，求其最大公约数和最小公倍数。
+     *
+     * 比如：12和20的最大公约数是4，最小公倍数是60。
+     */
+    @Test
+    public void t6(){
+        int m = 12;
+        int n = 20;
+        //判断两个数的大小
+        //最大公约数
+        int min = (m < n)?m:n;
+        for(int  i = min;i>1;i--){
+            if(m % i == 0 && n % i == 0){
+                System.out.println("最大公约数 = "+i);
+                break;
+            }
+        }
+
+        //最小公倍数
+        int max = (m > n)?m:n;
+        for (int j = max ;j <=m * n; j++){
+            if(j % m ==0 && j % n  ==0){
+                System.out.println("最小公倍数 = "+j);
+                break;
+            }
+        }
+    }
+
+    /**
+     * //九九乘法表
+     *   外层循环  = 行
+     *   内层循环  =  列
+     */
+    @Test
+    public void t7(){
+        for (int i = 1;i<=9;i++){
+            for (int j = 1;j<=i;j++){
+                System.out.print(i+" * "+j+" = "+i*j+"  ");
+            }
+            System.out.println();
+        }
+    }
+
+    /**
+     * 将一天的时间打印到控制台上
+     */
+    @Test
+    public void t8(){
+        int count = 0;
+        for (int hour = 0;hour<24;hour++){
+            for (int minute  = 0; minute < 60;minute++){
+                for (int second  = 0; second < 60;second++){
+                    count++;
+                    System.out.println(hour+"时"+minute+"分"+second+"秒");
+                }
+            }
+        }
+        System.out.println(count);
+    }
+
+    /**
+     * //1—100之间的所有质数(质数是只能被1和他本身整除的数称为质数,1既不是质数也不是合数)
+     */
+    @Test
+    public void t9(){
+        for (int i = 2;i<=100;i++){
+            boolean flag = true;
+            for (int j = 2;j<i;j++){
+                if(i % j == 0){  //不是质数
+                    flag = false;
+                    break;
+                }
+            }
+            if(flag){
+                System.out.println(i);
+            }
+        }
+    }
+
+    /**
+     * break
+     */
+    @Test
+    public void t10(){
+       ii: for (int j = 1; j <=5 ; j++) {
+            System.out.println("j="+j);
+          jj:  for (int i = 1; i <= 100; i++) {
+                if(i==5){
+                    break  ii;//结束当前循环
+                }
+                System.out.println("i="+i);
+            }
+        }
+    }
+
+    /**
+     * continue
+     */
+    @Test
+    public void t11(){
+      ii:  for (int j = 1; j <=5 ; j++) {
+            System.out.println("j="+j);
+         jj:  for (int i = 1; i <= 6; i++) {
+                if(i==5){
+                   continue ii;  //跳过当前循环 继续执行下一次循环
+                }
+                System.out.println("i="+i);
+            }
+        }
+    }
+}