Arrays.toString方法

源码如下 

public static String toString(int[] a) {
        if (a == null)
            return "null";
	int iMax = a.length - 1;
	if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0; ; i++) {
            b.append(a[i]);
	    if (i == iMax)
		return b.append(']').toString();
            b.append(", ");
        }
    }

当直接输出数组的时候输出的是地址，而调用Arrays.toString方法后可以输出数组

package com.zh;

import java.util.Arrays;

public class Exampel {
	public static void main(String[] args){
		int[] a = {1,2,3};
		System.out.println(a);
		System.out.println(Arrays.toString(a));
}
}

输出结果为

[I@7150bd4d
[1, 2, 3]