Java String replace()、replaceFirst() 和 replaceAll() 方法
javaobject oriented programmingprogramming
replace() 方法
String 类的 replace() 方法接受两个字符串值 −
一个表示要替换的字符串部分(子字符串)。
另一个表示需要替换指定子字符串的字符串。
使用此方法，您可以替换 java 中字符串的一部分。
示例
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class ReplaceExample {
public static void main(String args[]) throws FileNotFoundException {
String filePath = "D://input.txt";
Scanner sc = new Scanner(new File(filePath));
StringBuffer sb = new StringBuffer();
String input;
while (sc.hasNextLine()) {
input = sc.nextLine();
sb.append(input);
}
String content = sb.toString();
System.out.println(" 文件内容:\n"+contents);
System.out.println(" ");
//用所需单词替换单词
content = content.replace("Tutorialspoint", "TP");
System.out.println(" 替换所需单词后的文件内容:\n"+contents);
}
}
输出
Contents of the file: Hello how are you welcome to Tutorialspoint. At Tutorialspoint provide hundreds of technical tutorials for free. Contents of the file after replacing the desired word: Hello how are you welcome to TP. At TP provide hundreds of technical tutorials for free.
此方法的另一种变体也接受两个字符，分别代表现有字符和一个字符(以相同的顺序)，并用整个字符串中的新字符替换旧字符。
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class ReplaceExample {
public static void main(String args[]) throws FileNotFoundException {
String filePath = "D://input.txt";
Scanner sc = new Scanner(new File(filePath));
StringBuffer sb = new StringBuffer();
String input;
while (sc.hasNextLine()) {
input = sc.nextLine();
sb.append(input);
}
String content = sb.toString();
System.out.println(" ");
//用所需单词替换该单词
content = content.replace('T', '#');
System.out.println("替换所需单词后的文件内容:\n"+contents);
}
}
输出
Contents of the file: Hello how are you welcome to Tutorialspoint. At Tutorialspoint provide hundreds of technical tutorials for free. Contents of the file after replacing the desired word: Hello how are you welcome to #utorialspoint. At #utorialspoint provide hundreds of technical tutorials for free.
replaceAll() 方法
String 类的 replaceAll() 方法接受两个字符串(表示正则表达式和替换模式/字符串)，并用指定的模式/字符串替换匹配的值。
示例
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class replaceAllExample {
public static void main(String args[]) throws FileNotFoundException {
String filePath = "D://input.txt";
Scanner sc = new Scanner(new File(filePath));
StringBuffer sb = new StringBuffer();
String input;
while (sc.hasNextLine()) {
input = sc.nextLine();
sb.append(input);
}
String content = sb.toString();
System.out.println("文件内容:\n"+contents);
System.out.println();
//用所需单词替换该单词
content = content.replaceAll("\bTutorialspoint\b", "TP");
System.out.println("替换所需单词后的文件内容:\n"+contents);
}
}
输出
Contents of the file: Hello how are you welcome to Tutorialspoint. At Tutorialspoint provide hundreds of technical tutorials for free. Contents of the file after replacing the desired word: Hello how are you welcome to TP. At TP provide hundreds of technical tutorials for free.
replaceFirst() 方法
String 类的 replaceFirst() 方法 replaceFirst (也) 接受两个表示正则表达式和替换字符串的字符串，并用替换字符串替换第一个匹配项。
示例
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class ReplaceExample {
public static void main(String args[]) throws FileNotFoundException {
String filePath = "D://input.txt";
Scanner sc = new Scanner(new File(filePath));
StringBuffer sb = new StringBuffer();
String input;
while (sc.hasNextLine()) {
input = sc.nextLine();
sb.append(input);
}
String content = sb.toString();
System.out.println("文件内容:\n"+contents);
System.out.println(" ");
//用所需单词替换该单词
content = content.replaceFirst("Tutorialspoint", "TP");
System.out.println("替换所需单词后的文件内容:\n"+contents);
}
}
输出
Contents of the file: Hello how are you welcome to Tutorialspoint. At Tutorialspoint provide hundreds of technical tutorials for free. Contents of the file after replacing the desired word: Hello how are you welcome to TP. At Tutorialspoint provide hundreds of technical tutorials for free.
注意 − 所有这些方法都区分大小写。
