Why java unknown: import org.apache.commons.codec.binary.Base64;?

You need to add the Apache Commons Codec library to your project. You either need to download the *.jar file and add it to the project folder and project configuration or you let your build processor automatically download it. See https://mvnrepository.com/artifact/commons-codec/commons-codec/1.9 Latest is version 1.15 This website provides a download link for the *.jar file as well …

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How to identify object types in java

You forgot the .class: Note that this kind of code is usually the sign of a poor OO design. Also note that comparing the class of an object with a class and using instanceof is not the same thing. For example: is false, whereas is true. Whether one or the other must be used depends on …

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How to decompile a whole Jar file?

2009: JavaDecompiler can do a good job with a jar: since 0.2.5, All files, in JAR files, are displayed. See also the question “How do I “decompile” Java class files?”. The JD-Eclipse doesn’t seem to have changed since late 2009 though (see Changes).So its integration with latest Eclipse (3.8, 4.2+) might be problematic. JD-Core is actively maintained. Both are …

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Will Arrays.sort() increase time complexity and space time complexity?

I am assuming you are talking about Java here. So the loop will cost O(n) time, my question is that will Arrays.sort() cost more time? Yes, Arrays.sort(int[]) in all Java standard library implementations that I know, is an example of a comparison-based sort and thus must have worst-case complexity Ω(n log n). In particular, Oracle Java 7 uses …

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