Combining Strategies in a Java Strategy Pattern

Question

Examples below are shamelessly ripped off of java.dzone.com, and modified to suit my needs: Our interface: ``` public interface CompressionStrategy { public void compressFiles(ArrayList files); } ``` Our First Implementation ``` public class GZipCompressionStrategy implements CompressionStrategy { public File compressFiles(ArrayList files) { //using GZIP approach return archive; } } ``` Our Second Implementation: ``` public class TarCompressionStrategy implements CompressionStrategy { public File compressFiles(ArrayList files) { //using TAR approach return archive; } } ``` And this is the use given: ``` public class CompressionContext { private CompressionStrategy strategy; //this can be set at runtime by the application preferences public void setCompressionStrategy(CompressionStrategy strategy) { this.strategy = strategy; } //use the strategy public File createArchive(ArrayList files) { strategy.compressFiles(files); } } ``` Client Class with Main method ```…

Accepted Answer

You could create a `JoinedCompressionStrategy`

```
class JoinedCompressionStrategy implements CompressionStrategy {

private final CompressionStrategy s0;
    private final CompressionStrategy s1;

public JoinedCompressionStrategy(CompressionStrategy s0, CompressionStrategy s1) {
        this.s0 = s0;
        this.s1 = s1;
    }

public File compressFiles(ArrayList<File> files) {
        File archive = s0.compressFiles(files);
        return s1.compressFiles(Arrays.asList(archive));
    }
}
```

Combining Strategies in a Java Strategy Pattern

Solution

Problem