Note that the value of strArray1 is null, while the value of strArray2 is. The string array can also be declared as String strArray, but the previously mentioned methods are favoured and recommended. String stringArray2 = new String //declaring with size String stringArray1 //declaring without size A string array is declared by the following methods: How to Declare A String Array In Javaįor implementation ensure you get Java Installed. Now, let’s have a look at the implementation of Java string array. String Array is used to store a fixed number of Strings. java String array works in the same manner. It is considered as immutable object i.e, the value cannot be changed. Strings, on the other hand, is a sequence of character. Also, they are stored in a continuous memory location. You must be aware of Java Arrays, it is an object that contains elements of a similar data type. This article will touch up on following pointers, In this tutorial, l et us dig a bit deeper and understand the concept of String array in Java. A Java String Array is an object that holds a fixed number of String values. It is highly used by programmers due to its efficient and productive nature. If you are using Apache commons library, you can use repeat method to create a masking string of specified length.An array is a fundamental and crucial data structure Java programming language. 2) Mask credit card string using Apache Commons Basically we are replacing the range of characters with the mask string. We concatenate it with the mask string and then again concatenate both of them to the substring starting from index start index + mask length till string’s length. Once we have built the mask string, we take a substring from the original string starting from 0 index to start index. For example, if the start index is 0 and the end index is 4, the mask string will be “****”. We make a string of that length by appending mask character to StringBuilder. Next, we determine how many characters we need to mask by taking the difference of start and end index. The only important condition here is that the start index should not be greater than the end index. If the end index is greater than the string length, we assign string’s length to it. If the start index is less than 0, we make it 0. The maskString method takes input string, start index, end index and mask character as arguments. Check out the String substring method example for more details on how the substring method works. We will use substring method of the String class to do the same as given below. We are going to write a generic method which we can use to mask the character range from the string. 1) Mask credit card string using the substring method How to mask credit card numbers with *?įor masking the credit card number, we are going to assume that the card number is 16 digits long. For example, displaying a credit card number (where only the last four digits are visible while other digits are displayed as an asterisk * character) or displaying an email address where only the first character and domain is displayed while the rest of the characters are displayed as * symbol. Many times we need to mask part of the string with * character before displaying it on the front-end. The example also shows how to hide credit card number or email address with * using various approaches. Mask part of string example shows how to mask part of the String with * asterisk symbol.
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