java.util.Scanner 总结

 java.util.Scanner 用来取得用户的输入：

Scanner scan=new Scanner(System.in);//System.in in表示inputStream
int a=scan.nextInt();

String a=scan.nextLine();

double a=scan.nextDouble();

java.util.Scanner的总结
//构造方法(常用的三个)
//Scanner(File source)
//Scanner(InputStream source)
//Scanner(String source)

//对比两种方式的比较
//Scanner sc=new Scanner(System.in); 
//BufferedReader br=new BufferedReader(new InputStreamReader(System.in)) 

//方法
//useDelimiter(Pattern pattern)改变token的分割方式,默认的是空格,传Pattern对象
//useDelimiter(String pattern)改变token的分割方式,默认的是空格,传String

//hasNext();查看是否有token的分割段
//hasNextInt();查看是否有int类型的token的分割段
//nextInt();返回下一个int的数值
//nextLine();返回一行

//hasNext(Pattern pattern);返回下一个pattern类型的token

public class ScannerTest {
    public static void main(String[] args){
        String str = "1.1 22.2 s 4 5.3 6 7.5 8 9";
        Scanner scanner = new Scanner(str);
        //scanner.useDelimiter("\\.");
        while(scanner.hasNext()){
            if(scanner.hasNext(Pattern.compile("\\d\\.\\d"))){
                System.out.println(scanner.next());
            }else{
                scanner.next();//要调用一下next()相关的方法才会到下一个token
            }
        }            
    }
}

结果：
1.1
5.3
7.5


public class ScannerTest {
    public static void main(String[] args){
        String str = "1.2 s.4 5 6.7 8 9";
        Scanner scanner = new Scanner(str);
                  //token以.分割
        scanner.useDelimiter("\\.");
        while(scanner.hasNext()){
            System.out.println(scanner.next());
        }            
    }
}

The main use of java.util.Scanner is to read values from System.in or a file.

Many Scanner methods fit a simple pattern: nextXYZ() scans and returns a value of type XYZ.hasNextXYZ() returns true if something of type XYZ is available to be read next.

 scanner.close() close the inputStream.

参考：

http://www.leepoint.net/notes-java/summaries/summary-scanner.html