Differences in usage between tostring() and new string()

We do it in our daily work Base6 When encoding and decoding data to string, we often encounter toString() And new String(), Briefly summarize the usage differences between the two .

Take a chestnut

The test case ：

	@Test
	public void myTest1() {
		String value = "01234567012345670123456701234567";

		String base64String = Base64.toBase64String(value.getBytes());
        System.out.println("Base64 code ：" + base64String );

        byte[] decode = Base64.decode(base64String);
        System.out.println("Base64 decode ：" + decode );

	}

Output results ：

Base64 code ：MDEyMzQ1NjcwMTIzNDU2NzAxMjM0NTY3MDEyMzQ1Njc=
Base64 decode ：[[email protected]    

Process the decoded data ：

The test case above is slightly changed ：

	@Test
	public void myTest1() {
		String value = "01234567012345670123456701234567";

		String base64String = Base64.toBase64String(value.getBytes());
        System.out.println("Base64 code ：" + base64String );

        byte[] decode = Base64.decode(base64String);
        System.out.println("Base64 decode ：" + decode );

        String newString = new String(decode);
        System.out.println("newString result ：" + newString );

        String toString = decode.toString();
        System.out.println("toString result ：" + toString );
	}

Output results ：

Base64 code ：MDEyMzQ1NjcwMTIzNDU2NzAxMjM0NTY3MDEyMzQ1Njc=
Base64 decode ：[[email protected]

newString result ：01234567012345670123456701234567
toString result ：[[email protected] 

Compare the findings , Decoded data in the same byte array format , When doing string conversion , The output results are very different , Which usage is correct ？ Why? ？

It should be used here new String() Methods , because Base64 It is an algorithm for converting coding format .

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toString() And new String () Usage difference

• toString()： It's called Object Class toString() Method . Generally, it returns such a String：[class name]@[hashCode], In fact, it is the hash value of the object .

        This can be done from toString() From the source code of the method

Calling this method will get a  String：[class name]@[hashCode]  Such a string object .

• new String(byte[] parameter)： Enter the reference parameter It's an array of bytes , Use java The default encoding format for virtual machines , Decode and convert the input parameter byte array into the corresponding characters . If the default encoding format of the virtual machine is ISO-8859-1, according to ascii The character corresponding to the byte can be obtained from the encoding table .

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If used properly ？

• new String()： When using character transcoding , That is, when the byte array is converted to a string . For example, when encoding and decoding data / When encryption and decryption are converted to binary strings , You can directly use this method for conversion .
• toString()： When printing out objects , Or when you need to get the address of the object