流程控制

1.Scanner


  2. next()：以空白为结束符
    ​​Scanner scanner = new Scanner(System.in); System.out.print("使用next()输入：");//hello world if (scanner.hasNext()) { String str = scanner.next(); System.out.println("输入的是：" + str);//hello } scanner.close(); ​​
  3. nextLine()：以​​Enter​​为结束符
    ​​Scanner scanner = new Scanner(System.in); System.out.print("使用nextLine()输入：");//hello world if (scanner.hasNextLine()) { String str = scanner.nextLine(); System.out.println("输入的是：" + str);//hello world } scanner.close(); ​​
  4. 例题：输入多个数字，求其总和与平均数，每输入一个数字用回车确认，通过输入非数字来结束输入并输入出执行结果
    ​​Scanner scanner = new Scanner(System.in); System.out.print("请输入："); double sum = 0; int count = 0; while(scanner.hasNextDouble()) { double data = scanner.nextDouble(); System.out.println("你输入的是：" + data); sum += data; System.out.println("当前的和是：" + sum); ++count; System.out.println("当前是第" + count + "个数据"); } System.out.println("一共输入了" + count + "个数据"); System.out.println("总和是：" + sum); System.out.println("平均数是：" + sum /count); scanner.close(); ​​