[Java]常用字符串操作

public class T2 {

	public static void main(String[] args) {
		// startsWith, endsWith 判断字符串开头结尾
		String str = "StringMethod02.java";
		if (str.startsWith("String")) {
			System.out.println("string startsWith"+" 'String'");
		}
		if (str.endsWith(".java")) {
			System.out.println("string endsWith"+" '.java'");
		}
		// euqalsIgnoreCase忽略大小写比较字符串
		String strLower = "java";
		String strUpper = "JAVA";
		if (strLower.equalsIgnoreCase(strUpper)) {
			System.out.println("If ignore case, str1==str2");
		}
		// 字符串向字符数组的转化
		// str.toCharArray()
		String strJ = "Java is an object-oriented language";
		char cString[] = strJ.toCharArray();
		for (int i = 0 ; i < strJ.length() ; i++) {
			System.out.print(cString[i]+" ");
		}
		// 字符数组转化回字符串
		// copyValueOf(charArray)
		String strJCopy = String.copyValueOf(cString);
		System.out.println("\n"+strJCopy);
		// 查找字符串
		// indexOf("str") 找到返回下标，否则-1
		System.out.println("'mm' in the"+str+" : "+str.indexOf("lMethod"));
		// 测量字符串长度
		// str.length()
		System.out.println("length of str = "+str.length());
        // 替换字符串
		// replaceAll
		String str1 = str.replaceAll("java", "cpp");
		System.out.println("After replacement str1 = "+str1);
		// 根据指定的正则表达式拆分字符串
        // str.split(regex)
		String str4 = "115.157.200.135";
		String splitedArray [] = str4.split("\\.");
		System.out.println("SplitedArray.length = "+splitedArray.length);
		for (int i = 0 ; i < splitedArray.length ; i++) {
			System.out.print(splitedArray[i]+"\t");
		}
		System.out.println();
		// 截取字符串中的某一段
		// str.substring(startIndex, startIndex+subStr.length)
		String str5 = str4.substring(3, 3+2);
		System.out.println("str5 = "+str5);
		// 字符串大小写转换
		// str.toUpperCase()
		// str.toLowerCase()
		String strLowerCase = "lowerCase";
		System.out.println("strLowerCase = "+strLowerCase.toLowerCase());
		System.out.println("strUpperCase = "+strLowerCase.toUpperCase());
		// 去除开头结尾的空格
		// str.trim()
		String testBlankSpace = "     test str  *   ";
		System.out.println(testBlankSpace.trim());
	}
	
}

输出结果：