//查找字符或字符串		int in = str2.indexOf("d");				System.out.println("ab =" + in);				int la = str2.lastIndexOf("d");//课后				System.out.println("d =" + la);				String newStr = str2.substring(5);				newStr = str2.substring(5,6);				System.out.println("substring(） =" + newStr);				str2 = " ab cdd s ";				//去除前后空格		System.out.println("去空格 =" + str2.trim() + "后面");				//查找替换		System.out.println("查找替换空格 =" + str2.replace(" ", "") + "后面");				str2 = "abc,你好，abcd";				System.out.println("查找替换 =" + str2.replace("abc", "李四") + "");				System.out.println("查找替换 =" + str2.replaceFirst("abc", "张三") + "");				str2 = "abcdef";				//判断字符串开始和结束		System.out.println("判断起始1 =" + str2.startsWith("abc"));				System.out.println("判断起始2 =" + (str2.indexOf("abc") == 0));				System.out.println("判断结束  =" + str2.endsWith("ef") + "\t");