How to print arrays in Java development-javaTutorial-php.cn

How to print arrays in Java development

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Release： 2018-07-23 11:14:54

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Question

Because there is no toString() method in Java arrays, if I directly call the array toStrign() method, I will only get its memory address. Like this, it doesn't seem user-friendly:

int[] intArray = new int[] {1, 2, 3, 4, 5};
System.out.println(intArray);     // 有时候会输出 &#39;[I@3343c8b3&#39;

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So what is the simplest way to output an array? The effect I want is

// 数字数组:
int[] intArray = new int[] {1, 2, 3, 4, 5};
//输出: [1, 2, 3, 4, 5]

// 对象数组:
String[] strArray = new String[] {"John", "Mary", "Bob"};
//输出: [John, Mary, Bob]

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Answer

Use Arrays.toString(arr) or Arrays.deepToString(arr) to print (output) an array in Java 5 and above.

Don’t forget to introduce import java.util.Arrays;

package packageName;
import java.util.Arrays;

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int[] intArray = new int[] {1, 2, 3, 4, 5};
System.out.println(Arrays.toString(intArray));
//输出: [1, 2, 3, 4, 5]

String[] strArray = new String[] {"John", "Mary", "Bob"};
System.out.println(Arrays.deepToString(strArray));
*//输出: [John, Mary, Bob]

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The difference between Arrays.deepToString and Arrays.toString is that Arrays.deepToString is more suitable for printing multi-dimensional arrays
For example:

String[][] b = new String[3][4];
        for (int i = 0; i < 3; i++)
        {
            for (int j = 0; j < 4; j++)
            {
                b[i][j] = "A" + j;
            }
        } 
        System.out.println(Arrays.toString(b));
        //输出[[Ljava.lang.String;@55e6cb2a, [Ljava.lang.String;@23245e75, [Ljava.lang.String;@28b56559]
        System.out.println(Arrays.deepToString(b));
        //输出[[A0, A1, A2, A3], [A0, A1, A2, A3], [A0, A1, A2, A3]]

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