java 打印数组中所有元素的通用方法
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generic method to print all elements in an array
提问by user685275
I wanna a method that would loop any type array and print them, I have written the following:
我想要一个可以循环任何类型数组并打印它们的方法，我写了以下内容：
public static <T> void printArray(T[] arr){
for(T t: arr){
System.out.print(t+" ");
}
System.out.println("");
}
but this one only works for class arrays, what if I have a char[]instead of a Character[], or a int[]instead of an Integer[], or is there a way to cast them before hand? Thanks
但是这个只适用于类数组，如果我用 achar[]代替 a Character[]，或者用 aint[]代替 an Integer[]，或者有没有办法事先投射它们呢？谢谢
回答by Bozho
java.util.Arrays.toString(array)should do.
java.util.Arrays.toString(array)应该做。
- commons-langalso have that -
ArrayUtils.toString(array)(but prefer the JDK one) - commons-langallows for custom separator -
StringUtils.join(array, ',') - guavaalso allows a separator, and has the option to skip null values:
Joiner.on(',').skipNulls().join(array)
- commons-lang也有 -
ArrayUtils.toString(array)（但更喜欢 JDK 之一） - commons-lang允许自定义分隔符 -
StringUtils.join(array, ',') - 番石榴还允许使用分隔符，并且可以选择跳过空值：
Joiner.on(',').skipNulls().join(array)
All of these return a String, which you can then System.out.println(..)or logger.debug(..). Note that these will give you meaningful input if the elements of the array have implemented toString()in a meaningful way.
所有这些都返回 a String，然后您可以使用System.out.println(..)或logger.debug(..)。请注意，如果数组的元素toString()以有意义的方式实现，这些将为您提供有意义的输入。
The last two options, alas, don't have support for primitive arrays, but are nice options to know.
最后两个选项，唉，不支持原始数组，但知道是不错的选择。
回答by Aravindan R
You cant write a generic definition for primitive arrays. Instead, you can use method overloading and write a method for each primitive array type like this,
您不能为原始数组编写通用定义。相反，您可以使用方法重载并为每个基本数组类型编写一个方法，如下所示，
public static void printArray(int[] arr)
public static void printArray(short[] arr)
public static void printArray(long[] arr)
public static void printArray(double[] arr)
public static void printArray(float[] arr)
public static void printArray(char[] arr)
public static void printArray(byte[] arr)
public static void printArray(boolean[] arr)
回答by Pradeep C
private static void printArray(Object arr) {
// TODO Auto-generated method stub
String arrayClassName=arr.getClass().getSimpleName();
if (arrayClassName.equals("int[]"))
System.out.println(java.util.Arrays.toString((int[]) arr));
if (arrayClassName.equals("char[]"))
System.out.println(java.util.Arrays.toString((char[]) arr));
}
回答by Kal
You can't pass primitive arrays to the printArray() method
您不能将原始数组传递给 printArray() 方法
