java中的排序问题

Question

1，2，2，3，4按不同顺序排列，把每个组合输出用java怎么写啊？

Answer 1

采用插入算法实现排列：
[code="java"]
public class Composition {

char [][] insert(char [] a,char b) {
    int row = a.length+1;
    int col = row ;
    int insertPos = 0;//插入位置
    char [][] r = new char[row][col];
    for (int i = 0; i < row; i++) {
        for (int j = 0; j < col; j++) {
            if(j < insertPos) {
                r[i][j] = a[j];
            } else if(j > insertPos ){
                r[i][j] = a[j-1];
            } else {
                r[i][j] = b;
            }
        }
        insertPos++;
    }
    return r;
}

char [][] composition(char [] c) {
    char [][] r = {{c[0]}};
    char [][][] d ;
    int ii;
    for (int i = 1; i < c.length; i++) {
        d = new char[r.length][0][0];
        for (int j = 0; j < r.length; j++) {
            d[j]=insert(r[j],c[i]);
        }
        r = new char[d.length*d[0].length][0];
        ii = 0;
        for (int j = 0; j < d.length; j++) {
            for (int j2 = 0; j2 < d[j].length; j2++) {
                r[ii++] = d[j][j2];
            }
        }
    }
    return r;
}

public static void main(String[] args) {
    Composition com = new Composition();

// new char[]{'1','2','3','4','2','2'}
// new char[]{'1','2','3','4','2','2','2'}
char [][] r = com.composition(new char[]{'1','2','3','4','2'});
Set set = new HashSet();
System.out.println(r.length);
for (int i = 0; i < r.length; i++) {
set.add(new String(r[i]));
// System.out.println(r[i]);

}
System.out.println(set.size());
Iterator it = set.iterator();
while (it.hasNext()) {
System.out.println(it.next());

}
}
}
[/code]
代码就是就是上面的，具体解释等我有时间了给你解释