Java的String类讲解案例代码（String类使用：创建对象、比较、连接、截取、查找和替换、拆分...）StringBuf

package com.xiaoshan; import java.nio.charset.Charset; public class StringDemo { public static void main(String[] args) { // equalsMethod(); // lengthMethod(); // concatMethod(); // substringMethod(); // findIndexMethod(); // replaceMethod(); // splitMethod(); // splitLimitMethod(); // changeTypeMethod(); // formatMethod(); // judgmentMethod(); // otherMethod(); internMethod(); } public void createString(){ //1、直接赋值 String str1 = "Hello"; //2、构造方法 String str2 = new String("World"); } public static void equalsMethod(){ String str1 = "hello"; String str2 = "Hello"; System.out.println(str1.equals(str2)); System.out.println(str1.equalsIgnoreCase(str2)); System.out.println(str1.compareTo(str2)); } public static void lengthMethod(){ String str = "Hello World"; int length = str.length(); System.out.println(length); } public static void concatMethod(){ String str1 = "Hello"; String str2 = "World"; String result1 = str1 + ", " + str2; String result2 = str1.concat(", ").concat(str2); System.out.println(result1); // Hello, World System.out.println(result2); // Hello, World } public static void substringMethod(){ String str = "Hello World!"; String substr = str.substring(6, 11); String substr2 = str.substring(6); System.out.println(substr); System.out.println(substr2); } public static void findIndexMethod(){ String str = "Hello World"; int index1 = str.indexOf('o'); int index2 = str.indexOf("World"); int lastIndex1 = str.lastIndexOf('o'); int lastIndex2 = str.lastIndexOf("World"); System.out.println(index1); System.out.println(index2); System.out.println(lastIndex1); System.out.println(lastIndex2); char c = str.charAt(0); System.out.println(c); } public static void replaceMethod(){ String str = "Hello World"; String newStr1 = str.replace('l', 'L'); String newStr2 = str.replace("World", "Java"); System.out.println(newStr1); System.out.println(newStr2); String newStr3 = str.replaceFirst("l", "L"); String newStr4 = str.replaceAll("l", "L"); System.out.println(newStr3); System.out.println(newStr4); } public static void splitMethod(){ String str = "Java is a programming language"; String[] splitStr = str.split(" "); for (String s : splitStr) { System.out.println(s); } } public static void splitLimitMethod(){ String str = "Java,is,a,programming,language"; String[] splitStr = str.split(",", 3); for (String s : splitStr) { System.out.println(s); } } public static void changeTypeMethod(){ String str = "Hello, world!"; // 将字符串转换为字符数组 char[] charArray = str.toCharArray(); System.out.println("字符串转换为字符数组："); for (char c : charArray) { System.out.print(c + "、"); } System.out.println(); // 将其他类型转换为字符串 int number = 123; String numberStr = String.valueOf(number); System.out.println("将整数转换为字符串：" + numberStr); double decimal = 3.14; String decimalStr = String.valueOf(decimal); System.out.println("将浮点数转换为字符串：" + decimalStr); boolean bool = true; String boolStr = String.valueOf(bool); System.out.println("将布尔值转换为字符串：" + boolStr); // 使用平台的默认字符集将字符串编码为字节数组 byte[] bytes1 = str.getBytes(); System.out.println("默认字符集下的字节数组："); for (byte b : bytes1) { System.out.print(b + " "); } System.out.println(); // 使用指定字符集将字符串编码为字节数组（UTF-8） byte[] bytes2 = str.getBytes(Charset.forName("UTF-8")); System.out.println("UTF-8字符集下的字节数组："); for (byte b : bytes2) { System.out.print(b + " "); } System.out.println(); // 使用指定字符集将字符串编码为字节数组（GBK） byte[] bytes3 = str.getBytes(Charset.forName("GBK")); System.out.println("GBK字符集下的字节数组："); for (byte b : bytes3) { System.out.print(b + " "); } System.out.println(); } public static void formatMethod(){ int number = 123; double decimal = 3.14; // 使用格式化字符串 String formattedString = String.format("The number is %d and the decimal is %.2f", number, decimal); System.out.println("格式化字符串：" + formattedString); } public static void judgmentMethod(){ String str = "Hello, World!"; // 判断字符串是否包含传进来的字符串 String searchStr1 = "Hello"; boolean containsStr1 = str.contains(searchStr1); System.out.println("字符串 \"" + str + "\" 是否包含 \"" + searchStr1 + "\": " + containsStr1); String searchStr2 = "ChinaAi"; boolean containsStr2 = str.contains(searchStr2); System.out.println("字符串 \"" + str + "\" 是否包含 \"" + searchStr2 + "\": " + containsStr2); // 判断字符串是否以传进来的字符串开头 String prefix1 = "Hello"; boolean startsWithPrefix1 = str.startsWith(prefix1); System.out.println("字符串 \"" + str + "\" 是否以 \"" + prefix1 + "\" 开头: " + startsWithPrefix1); String prefix2 = "Hi"; boolean startsWithPrefix2 = str.startsWith(prefix2); System.out.println("字符串 \"" + str + "\" 是否以 \"" + prefix2 + "\" 开头: " + startsWithPrefix2); // 判断字符串是否以传进来的字符串结尾 String suffix1 = "World!"; boolean endsWithSuffix1 = str.endsWith(suffix1); System.out.println("字符串 \"" + str + "\" 是否以 \"" + suffix1 + "\" 结尾: " + endsWithSuffix1); String suffix2 = "Java"; boolean endsWithSuffix2 = str.endsWith(suffix2); System.out.println("字符串 \"" + str + "\" 是否以 \"" + suffix2 + "\" 结尾: " + endsWithSuffix2); // 判断字符串是否为空 boolean isEmpty = str.isEmpty(); System.out.println("字符串 \"" + str + "\" 是否为空: " + isEmpty); } public static void otherMethod(){ String input = " Hello, World! "; System.out.println("原始字符串: " + input); // 转小写 String lowercase = input.toLowerCase(); System.out.println("转小写后: " + lowercase); // 转大写 String uppercase = input.toUpperCase(); System.out.println("转大写后: " + uppercase); // 去掉左右两边的空格 String trimmed = input.trim(); System.out.println("去掉空格后: " + trimmed); } public static void internMethod(){ // 创建两个不同的字符串对象 String str1 = new String("Hello"); String str2 = new String("Hello"); // 执行intern()方法后，将字符串加入字符串常量池 String internStr1 = str1.intern(); String internStr2 = str2.intern(); // 检查两个字符串是否引用同一个字符串对象