Java: Merge Sort 2

MergeSort2.java

package introalgo.chap2;

import java.util.Random;

public class MergeSort2 {
  
  static int[] init( int max ) {
    int[] data = new int[max];
    Random random = new Random();
    for (int i = 0; i < data.length; i++) {
      data[i] = 100 + random.nextInt(900);
    }
    return data;
  }
  
  static void print( int[] data ) {
    for (int i = 0; i < data.length; i++) {
      System.out.printf("%d ", data[i]);
    }
    System.out.println();
  }
  
  static void merge( int[] data , int p , int q , int r ) {
    
    int lenLeft = q - p + 1;
    int lenRight = r - q;
    
    int[] dataLeft = new int[lenLeft];
    int[] dataRight = new int[lenRight];
    
    for (int i = 0; i < lenLeft; i++) {
      dataLeft[i] = data[p + i];
    }
    for (int i = 0; i < lenRight; i++) {
      dataRight[i] = data[1 + q + i];
    }
    
    // System.out.print("l: " + dataLeft.length + ": ");
    // print(dataLeft);
    // System.out.print("r: " + dataRight.length + ": ");
    // print(dataRight);
    
    for (int i = 0, j = 0, k = p; k <= r; k++) {
      
      // System.out.printf("%d %d %d \n", k, i, j);
      
      if ((i < dataLeft.length) && (j < dataRight.length)) {
        
        if (dataLeft[i] <= dataRight[j]) {
          data[k] = dataLeft[i];
          i = i + 1;
        } else {
          data[k] = dataRight[j];
          j = j + 1;
        }
        
      } else {
        
        if (i < dataLeft.length) {
          data[k] = dataLeft[i];
          i = i + 1;
        }
        
        if (j < dataRight.length) {
          data[k] = dataRight[j];
          j = j + 1;
        }
        
      }
      
    } // for (int i = 0, j = 0, k = p; k <= r; k++) {
    
  }
  
  static void mergesort( int[] data , int p , int r ) {
    
    // print(data);
    
    if (p >= r) {
      // stop here
      return;
    }
    
    int q = (p + r) / 2;
    
    mergesort(data, p, q);
    
    mergesort(data, q + 1, r);
    
    System.out.printf("%d,%d,%d: ", p, q, r);
    for (int i = p; i <= r; i++) {
      System.out.printf("%d ", data[i]);
    }
    System.out.print(" -> ");
    
    merge(data, p, q, r);
    
    for (int i = p; i <= r; i++) {
      System.out.printf("%d ", data[i]);
    }
    System.out.println();
    
  }
  
  public static void main( String[] args ) {
    
    int[] data = init(10);
    print(data);
    
    // merge(data, 1, 1, 2);
    // print(data);
    
    // merge(data, 0, 1, 2);
    // print(data);
    
    mergesort(data, 0, data.length - 1);
    print(data);
    
  }
  
}