排序--[冒泡，Arrays.sort]

冒泡：

public class Test01 {
    public static void main(String[] args){
        int [] a={12,25,3,54,24,69};
        for (int i = 1; i < a.length; i++) {        //若i从0开始，则i<a.length-1；i从1开始，则i<a.length
            for (int j = 0; j < a.length-1; j++) {   //j要比数组的长度少一且必须从0开始，否则当j=a.length-1,
                if (a[j]>a[j+1]) {        //就会有j+1=a.length
                    int temp = a[j];      //导致最后一个a[j+1]会溢出数组，造成数组溢出异常
                    a[j] = a[j+1];
                    a[j+1] = temp;
                }
            }
        }
        for (int i = 0; i < a.length; i++) {
            System.out.print(a[i]+"\t");
        } 
    }
}

------------------------------------------------------------------------

Arrays.sort：

import java.util.Arrays;
public class Test03 {
    public static void main(String[] args){
        int [] a={12,25,3,54,24,69};
        Arrays.sort(a);
        System.out.print(Arrays.toString(a));
    }
}