Scanner

src/tutorial/Scanners.java

@@ -0,0 +1,88 @@
+import java.util.Scanner;
+
+/**
+ * Created by Oliver on 28/06/2017.
+ */
+public class Scanners {
+    /*
+        next():
+        1、一定要读取到有效字符后才可以结束输入。
+        2、对输入有效字符之前遇到的空白，next() 方法会自动将其去掉。
+        3、只有输入有效字符后才将其后面输入的空白作为分隔符或者结束符。
+        next() 不能得到带有空格的字符串。
+     */
+    public static void Scanner_next() {
+        Scanner scanner = new Scanner(System.in);
+        System.out.println("Scanner.next方式接收数据: ");
+        do {
+            String next = scanner.next();
+            if (next.equals("q")) {
+                return;
+            }
+            System.out.println("Scanner.next(): " + next);
+        } while (scanner.hasNext());
+    }
+
+    /*
+        1、以Enter为结束符,也就是说 nextLine()方法返回的是输入回车之前的所有字符。
+        2、可以获得空白。
+     */
+    public static void Scanner_nextLine() {
+        Scanner scanner = new Scanner(System.in);
+        System.out.println("Scanner.nextLine方式接收数据: ");
+        do {
+            String line = scanner.nextLine();
+            System.out.println("Scanner.nextLine(): " + line);
+            if (line.equals("q")) {
+                return;
+            }
+        } while (scanner.hasNextLine());
+    }
+
+    public static void sum() {
+        Scanner scanner = new Scanner(System.in);
+        int sum = 0;
+        System.out.println("Input int number for sum: ");
+        do {
+            String s = scanner.next();
+            if (s.equals("q")) {
+                return;
+            } else {
+                int input = Integer.parseInt(s);
+                sum += input;
+                System.out.println("Input: " + input);
+                System.out.println("Now the sum is: " + sum);
+            }
+
+        } while (scanner.hasNext());
+    }
+
+    public static void average() {
+        Scanner scanner = new Scanner(System.in);
+        double sum = 0d;
+        double average;
+        int count = 0;
+        System.out.println("Input double number for average: ");
+        do {
+            String s = scanner.next();
+            if (s.equals("q")) {
+                return;
+            } else {
+                count++;
+                double input = Double.parseDouble(s);
+                sum += input;
+                average = sum / count;
+                System.out.println("Sum: " + sum);
+                System.out.println("Average: " + average);
+            }
+        } while (scanner.hasNext());
+    }
+
+
+    public static void main(String[] args) {
+        Scanner_next();
+        Scanner_nextLine();
+        sum();
+        average();
+    }
+}