JavaSE --- --- get to interact with the user keyboard input

1 Overview

　　　　1.1 JDK provided Scanner class for obtaining the keyboard input ;

　　　　1.2　　Scanner class is based on a regular expression is a text scanner , a file may be parsed from the input stream, the basic character string type value, a string value;

　　　　1.3　　Scanner class provides a plurality of different constructors , you can accept the file input stream, string as the data source, for parsing the data from the file input stream, string;

public final class Scanner implements Iterator<String>, Closeable {

    =====构造器
    private Scanner(Readable source, Pattern pattern) {
        assert source != null : "source should not be null";
        assert pattern != null : "pattern should not be null";
        this.source = source;
        delimPattern = pattern;
        buf = CharBuffer.allocate(BUFFER_SIZE);
        buf.limit(0);
        matcher = delimPattern.matcher(buf);
        matcher.useTransparentBounds(true);
        matcher.useAnchoringBounds(false);
        useLocale(Locale.getDefault(Locale.Category.FORMAT));
    }
   
    public Scanner(File source) throws FileNotFoundException {
        this((ReadableByteChannel)(new FileInputStream(source).getChannel()));
    }

    public Scanner(String source) {
        this(new StringReader(source), WHITESPACE_PATTERN);
    }

    public Scanner(InputStream source) {
        this(new InputStreamReader(source), WHITESPACE_PATTERN);
    }
}

　　　　1.4　　Scanner class method provides:

　　　　　　　　　hasNextXX () : Are there next;

　　　　　　　　　nextXX () : Get the next one;

import java.util.Scanner;

public class TestScanner {

    public static void main(String[] args){
        boolean flag=true;
        while (flag){
            //System.in标准输入，即键盘输入
            Scanner scanner=new Scanner(System.in);
            String inputContent=scanner.next();
            if (inputContent.equals("exit")){
                flag=false;
            }
            System.out.println(inputContent);
        }
    }
}

　　　　　　　　hasNextLine () : Is there a next line;

　　　　　　　　nextLine () : Gets the next row;