How do I convert InputStream to String?

By Wayan in Core API, IO 1 Comment

This example will show you how to convert an InputStream into String. In the code snippet below we read a data.txt file, could be from common directory or from inside a jar file.

package org.kodejava.io;

import java.io.*;
import java.nio.charset.StandardCharsets;

public class StreamToString {

    public static void main(String[] args) throws Exception {
        StreamToString demo = new StreamToString();

        // Get input stream of our data file. This file can be in
        // the root of your application folder or inside a jar file
        // if the program is packed as a jar.
        InputStream is = demo.getClass().getResourceAsStream("/student.csv");

        // Call the method to convert the stream to string
        System.out.println(demo.convertStreamToString(is));
    }

    private String convertStreamToString(InputStream stream) throws IOException {
        // To convert the InputStream to String we use the
        // Reader.read(char[] buffer) method. We iterate until the
        // Reader return -1 which means there's no more data to
        // read. We use the StringWriter class to produce the string.
        if (stream != null) {
            Writer writer = new StringWriter();

            char[] buffer = new char[1024];
            try (stream) {
                Reader reader = new BufferedReader(new InputStreamReader(stream,
                        StandardCharsets.UTF_8));
                int length;
                while ((length = reader.read(buffer)) != -1) {
                    writer.write(buffer, 0, length);
                }
            }
            return writer.toString();
        }
        return "";
    }
}

How do I convert string into InputStream?

By Wayan in Core API, IO 0 Comment

Here you will find how to convert string into java.io.InputStream object using java.io.ByteArrayInputStream class.

package org.kodejava.io;

import java.io.*;
import java.nio.charset.StandardCharsets;

public class StringToStream {
    public static void main(String[] args) {
        String text = "Converting String to InputStream Example";

        // Convert String to InputStream using ByteArrayInputStream
        // class. This class constructor takes the string byte array
        // which can be done by calling the getBytes() method.
        InputStream stream = new ByteArrayInputStream(text.getBytes(StandardCharsets.UTF_8));
    }
}

How do I split a string using Scanner class?

By Wayan in Core API, Util Package 0 Comment

Instead of using the StringTokenizer class or the String.split() method we can use the java.util.Scanner class to split a string.

package org.kodejava.util;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class ScannerTokenDemo {
    public static void main(String[] args) {
        // This file contains some data as follows:
        // a, b, c, d
        // e, f, g, h
        // i, j, k, l
        File file = new File("data.txt");
        try {
            // Here we use the Scanner class to read file content line-by-line.
            Scanner scanner = new Scanner(file);
            while (scanner.hasNextLine()) {
                String line = scanner.nextLine();

                // From the above line of code we got a line from the file
                // content. Now we want to split the line with comma as the 
                // character delimiter.
                Scanner lineScanner = new Scanner(line);
                lineScanner.useDelimiter(",");
                while (lineScanner.hasNext()) {
                    // Get each split data from the Scanner object and print
                    // the value.
                    String part = lineScanner.next();
                    System.out.print(part + ", ");
                }                
                System.out.println();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
}

How do I compare string regardless of their case?

By Wayan in Basic, Core API 0 Comment

Here is an example of comparing two strings for equality without considering their case sensitivity. To do this we can use equalsIgnoreCase() method of the String class. Let’s see an example below:

package org.kodejava.basic;

public class EqualsIgnoreCase {
    public static void main(String[] args) {
        String uppercase = "ABCDEFGHI";
        String mixed = "aBCdEFghI";

        // To compare two string equality regarding it case use the
        // String.equalsIgnoreCase method.
        if (uppercase.equalsIgnoreCase(mixed)) {
            System.out.println("Uppercase and Mixed equals.");
        }
    }
}

How do I insert a string in the StringBuilder?

By Wayan in Core API, Lang Package 0 Comment 
package org.kodejava.lang;

public class StringBuilderInsert {
    public static void main(String[] args) {
        StringBuilder alphabets = new StringBuilder("abcdfghopqrstuvwxyz");
        System.out.println("alphabets = " + alphabets);

        //  |a|b|c|d|f|g|h|i|....
        //  0|1|2|3|4|5|6|7|8|...
        //
        // From the above sequence you can see that the index of the string is
        // started from 0, so when we insert a string in the fourth offset it
        // means it will be inserted after the "d" letter. There are other overload
        // version of this method that can be used to insert other type of data
        // such as char, int, long, float, double, Object, etc.
        alphabets.insert(4, "e");
        System.out.println("alphabets = " + alphabets);

        // Here we insert an array of characters to the StringBuilder.
        alphabets.insert(8, new char[] {'i', 'j', 'k', 'l', 'm', 'n'});
        System.out.println("alphabets = " + alphabets);
    }
}

The result of the code snippet above:

alphabets = abcdfghopqrstuvwxyz
alphabets = abcdefghopqrstuvwxyz
alphabets = abcdefghijklmnopqrstuvwxyz