An output similar to the following code is expressed only by int type.

import java.util.stream.Collectors;
import java.util.stream.stream;
import java.util.stream.stream.Builder;

public class Partitions {
    public static void main(String[]args) {
        partition(7,7,0);
    }

    public static void partition(inti, intn, intr) {
        if(n==0){
            write(r);
            return;
        }

        if(i<n){
            for(int j=i;j>=1;j--){
                partition(j, n-j, push(r,j));
            }
        } else{
            for(int j=n;j>=1;j--){
                partition(j, n-j, push(r,j));
            }
        }
    }

    static void write (inter) {
        String numbers = stream(r).map(String::valueOf).collect(Collectors.joining(","));
        System.out.println("{"+number+"}");
    }

    static int push (intr, intj) {
        return(r<<3)|j;
    }

    static Stream<Integer>stream(inter){
        Builder<Integer>ret=Stream.builder();
        while(r>0){
            intv=r&0x7;
            ret.add(v);
            r=r>>>3;
        }
        return ret.build();
    }
}

import java.util.ArrayList;
import java.util.List;

public class Partitions {
  public static void main(String[]args) {
    partition(7,7).forEach(System.out:println);
  }

  public static List<List<Integer>>partition(inti, intn){
    List<List<Integer>>result=new ArrayList<List<Integer>>();

    if(n==0){
      result.add(new ArrayList<Integer>());
      return result;
    }

    for(int j = Math.min(i,n); j>0;j--){
      for(List<Integer>row:partition(j,n-j)){
        row.add(j);result.add(row);
      }
    }

    return result;
  }
}

// execution result
[7]
[1, 6]
[2, 5]
[1, 1, 5]
[3, 4]
[1, 2, 4]
[1, 1, 1, 4]
[1, 3, 3]
[2, 2, 3]
[1, 1, 2, 3]
[1, 1, 1, 1, 3]
[1, 2, 2, 2]
[1, 1, 1, 2, 2]
[1, 1, 1, 1, 1, 2]
[1, 1, 1, 1, 1, 1, 1]