打印 Java 数组的最简单方法是什么? [英] What's the simplest way to print a Java array?

查看:52
本文介绍了打印 Java 数组的最简单方法是什么?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

在 Java 中,数组不会覆盖 toString(),所以如果你尝试直接打印一个,你会得到 className + '@' + 的十六进制数组的 hashCode,由 定义Object.toString():

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the hashCode of the array, as defined by Object.toString():

int[] intArray = new int[] {1, 2, 3, 4, 5};
System.out.println(intArray);     // prints something like '[I@3343c8b3'

但通常,我们实际上想要更像 [1, 2, 3, 4, 5] 的东西.最简单的方法是什么?以下是一些示例输入和输出:

But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:

// Array of primitives:
int[] intArray = new int[] {1, 2, 3, 4, 5};
//output: [1, 2, 3, 4, 5]

// Array of object references:
String[] strArray = new String[] {"John", "Mary", "Bob"};
//output: [John, Mary, Bob]

推荐答案

从 Java 5 开始,您可以使用 Arrays.toString(arr)Arrays.deepToString(arr)对于数组中的数组.请注意,Object[] 版本对数组中的每个对象调用 .toString().输出甚至按照您要求的方式进行修饰.

Since Java 5 you can use Arrays.toString(arr) or Arrays.deepToString(arr) for arrays within arrays. Note that the Object[] version calls .toString() on each object in the array. The output is even decorated in the exact way you're asking.

示例:

  • 简单数组:

String[] array = new String[] {"John", "Mary", "Bob"};
System.out.println(Arrays.toString(array));

输出:

[John, Mary, Bob]

  • 嵌套数组:

    String[][] deepArray = new String[][] {{"John", "Mary"}, {"Alice", "Bob"}};
    System.out.println(Arrays.toString(deepArray));
    //output: [[Ljava.lang.String;@106d69c, [Ljava.lang.String;@52e922]
    System.out.println(Arrays.deepToString(deepArray));
    

    输出:

    [[John, Mary], [Alice, Bob]]
    

  • double 数组:

    double[] doubleArray = { 7.0, 9.0, 5.0, 1.0, 3.0 };
    System.out.println(Arrays.toString(doubleArray));
    

    输出:

    [7.0, 9.0, 5.0, 1.0, 3.0 ]
    

  • int 数组:

    int[] intArray = { 7, 9, 5, 1, 3 };
    System.out.println(Arrays.toString(intArray));
    

    输出:

    [7, 9, 5, 1, 3 ]
    

  • 这篇关于打印 Java 数组的最简单方法是什么?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!

    查看全文
    登录 关闭
    扫码关注1秒登录
    发送“验证码”获取 | 15天全站免登陆