System Class in Java

Note to myself:

System.arraycopy method:

Copy the content of an array (source) to another array (destination), beginning at the specified position, to the specified position of the destination array.

public static void arraycopy (Object source, int sourcePos, Object destination, int destPos, int length)

For example, the following code uses arraycopy to copy the contents of array1 to array2.

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public class MainClass {
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  public static void main(String[] a) {
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    int[] array1 = { 1, 2, 3, 4 };
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    int[] array2 = new int[array1.length];
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    System.arraycopy(array1, 0, array2, 0, array1.length);
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    for(int i: array2){
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      System.out.println(i);
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    }
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  }
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}

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Output:
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1
3
2
4
3
5
4

Redirect the output of System.out to a file.

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import java.io.File;
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import java.io.IOException;
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import java.io.PrintStream;
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public class MainClass {
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  public static void main(String[] args) {
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    File file = new File("C:\\temp\\debug.txt");
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    try {
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      PrintStream ps = new PrintStream(file);
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      System.setOut(ps);
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    } catch (IOException e) {
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    }
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    System.out.println("To File");
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  }
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}

Loading Native Code

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public class Main {
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  public static void main(String[] argv) throws Exception {
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    System.loadLibrary("libraryName");
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  }
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}