学java崩溃的第一天

终于觉得自己写了完美的代码，结果一运行排序不对，debug了好几次

public class HelloWorld {
    public static void main(String[] args) {
        int[] a = new int[5];
        System.out.println("原始排序为：");
        for (int  i = 0; i < a.length; i++){
            a[i] = (int) (Math.random()*100);
            System.out.print(a[i] + " ");
        }

        System.out.println("");
        for (int i = 1; i < a.length; i++){
            for (int j = i - 1; j < a.length; j++){
                if (a[i-1] > a[j]){
                    int b = a[i-1];
                    a[i-1] = a[j];
                    a[j] = b;
                }
            }
        }

        for (int i = 0; i < a.length; i++){
            System.out.print(a[i] + " ");
        }
    }
}

结果才发现数组的第一位是a[0]

public class HelloWorld {
    public static void main(String[] args) {
        int[] a = new int[5];
        System.out.println("原始排序为：");
        for (int  i = 0; i < a.length; i++){
            a[i] = (int) (Math.random()*100);
            System.out.print(a[i] + " ");
        }

        System.out.println("");
        for (int i = 1; i < a.length; i++){
            for (int j = i ; j < a.length; j++){
                if (a[i-1] > a[j]){
                    int b = a[i-1];
                    a[i-1] = a[j];
                    a[j] = b;
                }
            }
        }

        for (int i = 0; i < a.length; i++){
            System.out.print(a[i] + " ");
        }
    }
}