update basics (examplehub#105)

realDuYuanChao · github-actions · web-flow · commit 608db282d4d4 · 2021-04-14T09:49:49.000+08:00
* static example

* date example

* for in

* add range function

* return example

* constructor example

* update this keyword

* Formatted with Google Java Formatter

Co-authored-by: github-actions &lt;${GITHUB_ACTOR}@users.noreply.github.com&gt;
diff --git a/src/main/java/com/examplehub/basics/CalendarExample.java b/src/main/java/com/examplehub/basics/CalendarExample.java
@@ -0,0 +1,10 @@
+package com.examplehub.basics;
+
+import java.util.Calendar;
+
+public class CalendarExample {
+  public static void main(String[] args) {
+    Calendar calendar = Calendar.getInstance();
+    System.out.println(calendar);
+  }
+}
diff --git a/src/main/java/com/examplehub/basics/ConstructorExample.java b/src/main/java/com/examplehub/basics/ConstructorExample.java
@@ -0,0 +1,37 @@
+package com.examplehub.basics;
+
+public class ConstructorExample {
+  public static void main(String[] args) {
+    ConstructorTest test = new ConstructorTest();
+    System.out.println(test); /* ConstructorTest{username='admin', password='112233'} */
+
+    test = new ConstructorTest("root", "root");
+    System.out.println(test); /* ConstructorTest{username='root', password='root'} */
+  }
+}
+
+class ConstructorTest {
+  public String username;
+  public String password;
+
+  public ConstructorTest() {
+    this("admin", "112233");
+  }
+
+  public ConstructorTest(String username, String password) {
+    this.username = username;
+    this.password = password;
+  }
+
+  @Override
+  public String toString() {
+    return "ConstructorTest{"
+        + "username='"
+        + username
+        + '\''
+        + ", password='"
+        + password
+        + '\''
+        + '}';
+  }
+}
diff --git a/src/main/java/com/examplehub/basics/DateExample.java b/src/main/java/com/examplehub/basics/DateExample.java
@@ -0,0 +1,9 @@
+package com.examplehub.basics;
+
+import java.util.Date;
+
+public class DateExample {
+  public static void main(String[] args) {
+    System.out.println(new Date());
+  }
+}
diff --git a/src/main/java/com/examplehub/basics/ForInExample.java b/src/main/java/com/examplehub/basics/ForInExample.java
@@ -0,0 +1,47 @@
+package com.examplehub.basics;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ForInExample {
+  public static void main(String[] args) {
+    int[] numbers = {5, 55, 555, 5555, 55555};
+    /*
+     * 5
+     * 55
+     * 555
+     * 5555
+     * 55555
+     */
+    for (int number : numbers) {
+      System.out.println(number);
+    }
+
+    /*
+     * E
+     * H
+     */
+    for (char ch : "ExampleHub".toCharArray()) {
+      if (Character.isUpperCase(ch)) {
+        System.out.println(ch);
+      }
+    }
+
+    /*
+     * Java
+     * Python
+     * C
+     */
+    List<String> books =
+        new ArrayList<String>() {
+          {
+            add("Java");
+            add("Python");
+            add("C");
+          }
+        };
+    for (String book : books) {
+      System.out.println(book);
+    }
+  }
+}
diff --git a/src/main/java/com/examplehub/basics/ReturnExample.java b/src/main/java/com/examplehub/basics/ReturnExample.java
@@ -0,0 +1,19 @@
+package com.examplehub.basics;
+
+public class ReturnExample {
+  public static void main(String[] args) {
+    System.out.println(test(15, 10)); /* 1 */
+    System.out.println(test(10, 15)); /* -1 */
+    System.out.println(test(10, 10)); /* 0 */
+  }
+
+  private static int test(int test, int target) {
+    if (test > target) {
+      return 1;
+    }
+    if (test < target) {
+      return -1;
+    }
+    return 0;
+  }
+}
diff --git a/src/main/java/com/examplehub/basics/StaticExample.java b/src/main/java/com/examplehub/basics/StaticExample.java
@@ -0,0 +1,24 @@
+package com.examplehub.basics;
+
+public class StaticExample {
+  public static void main(String[] args) {
+    StaticTest staticTest = new StaticTest();
+    StaticTest.increment();
+    System.out.println(StaticTest.count); /* 1 */
+    staticTest.method(); /* normal method */
+    System.out.println(StaticTest.count); /* 2 */
+  }
+}
+
+class StaticTest {
+  public static int count = 0;
+
+  public static void increment() {
+    count++;
+  }
+
+  public void method() {
+    increment();
+    System.out.println("normal method");
+  }
+}
diff --git a/src/main/java/com/examplehub/basics/ThisKeywordExample.java b/src/main/java/com/examplehub/basics/ThisKeywordExample.java
@@ -13,6 +13,9 @@ public static void main(String[] args) {
 
     rectangle = new Rectangle(1, 1, 3, 4);
     System.out.println(rectangle); /* Rectangle{x=1, y=1, width=3, height=4} */
+
+    Counter counter = new Counter();
+    System.out.println(counter.increment().increment().increment().getCount()); /* 3 */
   }
 }
 
@@ -52,3 +55,16 @@ public String toString() {
     return "Rectangle{" + "x=" + x + ", y=" + y + ", width=" + width + ", height=" + height + '}';
   }
 }
+
+class Counter {
+  private int count = 0;
+
+  public Counter increment() {
+    count++;
+    return this;
+  }
+
+  public int getCount() {
+    return count;
+  }
+}
diff --git a/src/main/java/com/examplehub/maths/Range.java b/src/main/java/com/examplehub/maths/Range.java
@@ -0,0 +1,30 @@
+package com.examplehub.maths;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Range {
+  public static int[] range(int n) {
+    List<Integer> numbers = new ArrayList<>();
+    for (int i = 0; i < n; ++i) {
+      numbers.add(i);
+    }
+    return numbers.stream().mapToInt(i -> i).toArray();
+  }
+
+  public static int[] range(int start, int end) {
+    List<Integer> numbers = new ArrayList<>();
+    for (int i = start; i < end; ++i) {
+      numbers.add(i);
+    }
+    return numbers.stream().mapToInt(i -> i).toArray();
+  }
+
+  public static int[] range(int start, int end, int step) {
+    List<Integer> numbers = new ArrayList<>();
+    for (int i = start; i < end; i += step) {
+      numbers.add(i);
+    }
+    return numbers.stream().mapToInt(i -> i).toArray();
+  }
+}
diff --git a/src/test/java/com/examplehub/maths/RangeTest.java b/src/test/java/com/examplehub/maths/RangeTest.java
@@ -0,0 +1,15 @@
+package com.examplehub.maths;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.Arrays;
+import org.junit.jupiter.api.Test;
+
+class RangeTest {
+  @Test
+  void testRange() {
+    assertTrue(Arrays.equals(new int[] {0, 1, 2, 3, 4}, Range.range(5)));
+    assertTrue(Arrays.equals(new int[] {10, 11, 12, 13, 14, 15}, Range.range(10, 16)));
+    assertTrue(Arrays.equals(new int[] {1, 3, 5, 7, 9}, Range.range(1, 10, 2)));
+  }
+}

Original file line number	Diff line number	Diff line change
`@@ -13,6 +13,9 @@ public static void main(String[] args) {`
`13`	`13`
`14`	`14`	`rectangle = new Rectangle(1, 1, 3, 4);`
`15`	`15`	`System.out.println(rectangle); /* Rectangle{x=1, y=1, width=3, height=4} */`
	`16`	`+`
	`17`	`+ Counter counter = new Counter();`
	`18`	`+ System.out.println(counter.increment().increment().increment().getCount()); /* 3 */`
`16`	`19`	`}`
`17`	`20`	`}`
`18`	`21`
`@@ -52,3 +55,16 @@ public String toString() {`
`52`	`55`	`return "Rectangle{" + "x=" + x + ", y=" + y + ", width=" + width + ", height=" + height + '}';`
`53`	`56`	`}`
`54`	`57`	`}`
	`58`	`+`
	`59`	`+class Counter {`
	`60`	`+ private int count = 0;`
	`61`	`+`
	`62`	`+ public Counter increment() {`
	`63`	`+ count++;`
	`64`	`+ return this;`
	`65`	`+ }`
	`66`	`+`
	`67`	`+ public int getCount() {`
	`68`	`+ return count;`
	`69`	`+ }`
	`70`	`+}`