SOLID Java 8

UpsertTask.java

public class UpsertTask {

    private interface Executor {
        void execute() throws TaskExecutionException;
    }

    private Executor executeMethod;
    
    public void prepare() {
        if (/*something*/) {
            executeMethod = this::executeInsert;
        } else {
            executeMethod = this::executeUpdate;
        }
    }
    
    public void execute() throws TaskExecutionException {
        executeMethod.execute();
    }
    
    private void executeInsert() throws TaskExecutionException {
        // ...
    }
    
    private void executeUpdate() throws TaskExecutionException {
        // ...
    }
    
}