String str = new String("abcdef"); charAt str.charAt(3) == 'd' compareTo compareToIgnoreCase concat str.concat(str) == "abcdefabcdef" contains str.contains("bcd") == TRUE endsWith str.endsWith("ef") == TRUE startsWith str.startsWith("abc") == TRUE equals str.equals(new String("abcdef")) == TRUE equalsIgnoreCase str.equalsIgnoreCase(new String("ABcdEf")) == TRUE indexOf str. isEmpty lastIndexOf length replace split subString format trim toLower toUpper valueOf