java实现排列组合

java实现排列组合

String []b=new String[a.length-1];
for(int i=0;i{
b[i]="["+a[i]+","+a[i+1]+"]";

}
for(String s:b)
System.out.println(s);

没看太懂题目意思，是这样吗追问我的意思是要取出1,2,3,4,12,23,34,123,234,1234这种数据追答char[] a={'1','2','3','4'};

for(int i=0;i {
for(int j=0;j {
for(int k=0;k {
System.out.print(a[j+k]);
}
System.out.print(",");
}
System.out.println();
}

2位数排列组合的话，应该不止[1,2],[2,3],[3,4]吧？
代码在下面：
private void pailie(char[] a){
    for(int i = 0; i        for(int j = i+1; j < a.length; j++){
            System.out.print("["+a[i]+","+a[j]+"]");
        }
    }
}

char[] a={'1','2','3','4'};
String b= "";
String c= "";
for (int i = 0; i < a.length-1; i++) {
b="["+a[i]+","+a[i+1]+"]";
c+=b;
}
System.out.println(c);
追问我的意思是要取出1,2,3,4,12,23,34,123,234,1234这种数据追答
一直写数据库好久没写java了 太菜不要介意
char[] a={'1','2','3','4'};
String b= "";
String c= "";
for (int i = 0; i < a.length; i++) {
b=a[i]+",";
c+=b;
}
for (int i = 0; i < a.length-1; i++) {
b=a[i]+""+a[i+1]+",";
c+=b;
}
for (int i = 0; i < a.length-2; i++) {
b=a[i]+""+a[i+1]+""+a[i+2]+",";
c+=b;
}
for (int i = 0; i < a.length-3; i++) {
b=a[i]+""+a[i+1]+""+a[i+2]+""+a[i+3]+"";
c+=b;
}
System.out.println(c);