【数组的使用续篇】

public class Test {
    public static void main(String[] args) {
        int[] array={1,2,3,4,5};
        String ret = Arrays.toString(array);
        //或者这种System.out.println(Arrays.toString(array));
        System.out.println(ret);
    }
}

public class Test {
    public static void main(String[] args) {
        int[] array={7,18,5,27,100};
        System.out.println(Arrays.toString(array));
        Arrays.sort(array);//排序方法
        System.out.println(Arrays.toString(array));
    }
}

public class Test {
    public static void main(String[] args) {
        int[] array = {7, 18, 5, 27, 100};
        System.out.println(myToString(array));
        Arrays.sort(array);//排序方法
        System.out.println(myToString(array));
        int[] array1 = null;//当数组为空时，打印null
        System.out.println(myToString(array1));
        int[] array2={ };//当数组为0时，打印[]
        System.out.println(myToString(array2));
    }
    public static String myToString(int[] array){
        if(array==null){
            return null;
        }
        if(array.length==0 )
        {
            return "[]";
        }
        String ret ="[";
        for (int i = 0; i <array.length ; i++) {
            ret += array[i]+" ";
            if(i != array.length-1){
                ret += ",";
            }
        }
        ret += "]";
        return ret;
    }
}

//冒泡排序
public class Test {
    public static void main(String[] args) {
        int[] array={2,1,8,16,22,7};
        Bubblesort(array);
        Arrays.sort(array);//给数组排序大小
        System.out.println(Arrays.toString(array));
    }
    public static void Bubblesort(int [] array){
        if(array==null){
            return ;
        }
        for (int i = 0; i < array.length; i++) {
            boolean flg =false;//优化代码时间复杂度
            for (int j = 0; j <array.length-1-i ; j++) {
                int tmp = 0;
                if(j>j+1){
                    tmp =array[j] ;
                    array[j] = array[j+1];
                    array[j+1] =tmp;
                    flg =true;
                }
            }
            if(!flg){
                return ;
            }
        }
    }
}

public class Test {
    public static void main(String[] args) {
        int[] array={2,3,4,5};
        reverse(array);
        System.out.println(Arrays.toString(array));
    }
    public static void reverse(int[] array){
        if(array==null){
            return ;
        }
        int i=0;
        int j=array.length-1;
        //当i>=j时说明已经交换完
        //要有条件让交换停下来
       while(i<j){
           int tmp= array[i];
           array[i] = array[j];
           array[j] = tmp;
           i++;
           j--;
       }
    }
}