java.util包學習之Scanner類

Scanner類常用的場景爲：1.控制檯輸入；2.字符串分割；3.文本整行讀取。

示例代碼如下：

package test.java.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Scanner;

/**
 * Scanner類的常用方法彙總
 * @author Lukas
 *
 */
public class ScannerTest {

	public static void main(String[] args) {
//		consoleInput();
//		splitString();
//		readFileByLine();
	}

	/**
	 * 1：控制檯輸入輸出
	 */
	private static void consoleInput() {
		Scanner in = new Scanner(System.in);
		while(in.hasNext()){
			Object input = in.nextLine();
			System.out.println("input ==> " + input);
			closeSacnner(in, input);
		}
	}

	/**
	 * 2：按字符分割字符串（默認按照空格分隔）
	 */
	private static void splitString() {
		String inputStr = "123 456,abc.def...張三|李四";
		Scanner in = new Scanner(inputStr);
		in.useDelimiter(" |,|\\.|\\|");
		while(in.hasNext()){
			String input = in.next();
			System.out.println("input ==> " + input);
		}
		in.close();
	}

	/**
	 * 3：按行讀取文件
	 */
	private static void readFileByLine() {
		InputStream is = null;
		try {
			is = new FileInputStream(new File("src/test/java/util/HelloWorld.java"));
			Scanner in = new Scanner(is);
			while(in.hasNextLine()){
				String input = in.nextLine();
				System.out.println("input ==> " + input);
			}
			in.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} finally {
			try {
				is.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	/**
	 * 關閉Scanner流
	 * @param in
	 * @param input
	 */
	private static void closeSacnner(Scanner in, Object input) {
		if("bye".equalsIgnoreCase(input.toString())){
			System.out.println("bye");
			in.close();
			System.exit(0);
		}
	}
}