Scanner类

Java5: java.util.Scanner包基础语法：Scanner s = new Scanner(System.in);

package Scanner; import java.util.Scanner; public class Demo01 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("使用next方法接收："); if (scanner.hasNext()){ String str = scanner.next(); System.out.println("输入的内容为:" + str); } // 凡是属于IO流的类，如果不关闭会一直占用资源，养成良好的习惯。 scanner.close(); } } package Scanner; import java.util.Scanner; public class Demo02 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("使用nextLine方法接收："); if (scanner.hasNextLine()){ String str = new String(); str = scanner.nextLine(); System.out.println("输入的内容为:" + str); } scanner.close(); } }

package Scanner; import java.util.Scanner; public class Demo04 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); int i = 0; float f = 0.0f; System.out.println("请输入整数："); if(scanner.hasNextInt()){ i = scanner.nextInt(); System.out.println("整数数据："+i); }else{ System.out.println("输入的不是整数数据。"); } System.out.println("请输入小数："); if(scanner.hasNextFloat()){ f = scanner.nextFloat(); System.out.println("小数数据："+f); }else{ System.out.println("输入的不是浮点数据。"); } } } package Scanner; import java.util.Scanner; public class Demo05 { public static void main(String[] args) { // 输入多个数字，求和和平均数 Scanner scanner = new Scanner(System.in); double sum = 0; int n = 0; while(scanner.hasNextDouble()){ double x = scanner.nextDouble(); n++; sum += x; } System.out.println("总和："+ sum); System.out.println("平均数:"+ (sum /n)); System.out.println(); scanner.close(); } }