Java课后题第十二章：12.11（删除文本）

目录

1、使用编译器调用

2、使用Command line调用

3、运行示例

import java.util.Scanner;

public class DeleteTxt {
    public static void main(String[] args) throws IOException {
        File sourceFile = new File("John.txt");
        File targetFile = new File("John1.txt");
        try (Scanner input = new Scanner(sourceFile);
             PrintWriter output = new PrintWriter(targetFile))
        {
            while (input.hasNext()) {
                String s1 = input.nextLine();
                String s2 = s1.replace("John", " ");
                output.println(s2);
            }
        }
    }
}

2、使用Command line调用

        1）改args.length!=3        2）原args[3]替换为空字符串

// command line
java ReplaceText.java John.txt NewJohn1.txt John

import java.io.File;
import java.io.PrintWriter;
import java.util.Scanner;

public class ReplaceText {
    public static void main(String[] args) throws Exception {
        if (args.length != 3) {  
            System.out.println("Usage:java ReplaceText sourceFile targetFile oldStr newStr");
            System.exit(1);
        }
        File sourceFile = new File(args[0]);
        if (!sourceFile.exists()) {
            System.out.println("Source file" + args[0] + "does not exist");
            System.exit(2);
        }
        File targetFile = new File(args[1]);
        if (targetFile.exists()) {
            System.out.println("Target file " + args[1] + " already exists");
            System.exit(3);
        }
        try (
                Scanner input = new Scanner(sourceFile);
                PrintWriter output = new PrintWriter(targetFile)) {
            while (input.hasNext()) {
                String s1 = input.nextLine();
                String s2 = s1.replaceAll(args[2], ""); 
                output.println(s2);
            }
        }
    }
}

3、运行示例

John.txt-记事本
John is a good man.
John is a good man.

NewJohn.txt-记事本
 is a good man.
 is a good man.