method

src/tutorial/examples/MethodExample.java

@@ -0,0 +1,142 @@
+package examples;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Created by Oliver on 08/07/2017.
+ */
+public class MethodExample {
+    public static void main(String[] args) {
+        /* 斐波那契数列 */
+        System.out.println("fibonacci: " + fibonacci(2));
+
+        /* 阶乘 */
+        System.out.println("factorial: " + factorial(5));
+
+        /* instanceOf 关键字用法 */
+        instanceOf(3.14f);
+        instanceOf("String");
+
+        /* continue 关键字用法 */
+        continues();
+
+        /* enum 和 switch 语句使用 */
+        Language language = Language.Java;
+        enum_switch(language);
+
+        /* Enum（枚举）构造函数及方法的使用 */
+        try_enum();
+
+        /* Varargs 可变参数使用 */
+        int[] intArrays = {1, 3, 5};
+        System.out.println("Sum of variable args: " + varargs(intArrays));
+
+        /* 重载(overloading)方法中使用 Varargs */
+        double[] doubleArrays = {1.1, 2.2, 3.3};
+        System.out.println("Sum of variable args: " + varargs(doubleArrays));
+    }
+
+    public static List<Long> fibonacci(long count) {
+        List<Long> list = new ArrayList<>();
+        if (count <= 1) {
+            list.add(0l);
+            return list;
+        } else {
+            list.add(0l);
+            list.add(1l);
+            long next;
+            for (int i = 2; i < count; i++) {
+                next = list.get(i - 2) + list.get(i - 1);
+                list.add(next);
+            }
+        }
+        return list;
+    }
+
+    public static long factorial(long num) {
+        long result = 1;
+        if (num > 1) {
+            for (int i = 1; i <= num; i++) {
+                result = result * i;
+            }
+        }
+        return result;
+    }
+
+    public static void instanceOf(Object o) {
+        if (o instanceof Integer) {
+            System.out.println("Object is instanceOf Integer");
+        } else if (o instanceof Float) {
+            System.out.println("Object is instanceOf Float");
+        } else if (o instanceof String) {
+            System.out.println("Object is instanceOf String");
+        }
+    }
+
+    public static void continues() {
+        StringBuffer searchstr = new StringBuffer("hello how are you. ");
+        int found = 0;
+        for (int i = 0; i < searchstr.length(); i++) {
+            if (searchstr.charAt(i) == 'h') {
+                found++;
+                continue;
+            }
+        }
+        System.out.printf("%d 'h' found in 'hello how are you. '%n", found);
+    }
+
+    enum Language {
+        Java(1), Python(2), Go(3), Javascript(4);
+        private int id;
+
+        Language(int id) {
+            this.id = id;
+        }
+
+        public int getId() {
+            return this.id;
+        }
+    }
+
+    public static void enum_switch(Language language) {
+        switch (language) {
+            case Java:
+                System.out.println("Language: Java");
+                break;
+            case Python:
+                System.out.println("Language: Python");
+                break;
+            case Go:
+                System.out.println("Language: Go");
+                break;
+            case Javascript:
+                System.out.println("Language: Javascript");
+                break;
+        }
+    }
+
+    public static void try_enum() {
+        for (Language l : Language.values()) {
+            System.out.printf("%s: %d", l, l.getId());
+            System.out.println();
+        }
+    }
+
+    public static int varargs(int... varargs) {
+        int sum = 0;
+        for (int i = 0; i < varargs.length; i++) {
+            sum += varargs[i];
+        }
+        return sum;
+    }
+
+    public static double varargs(double... varargs) {
+        double sum = 0;
+        for (double d : varargs) {
+            sum += d;
+        }
+        return sum;
+    }
+}
+