Java中的 Charset canEncode() 方法及示例

canEncode() 方法是Java.nio.charset的内置方法，用于检查特定字符集是否支持编码。除了少数之外，几乎每个字符集都可以编码。

语法：

public boolean canEncode()

参数：该函数不接受任何参数。

返回值：该函数返回一个布尔值。如果它支持编码，则返回 true，否则返回 false。

下面是上述函数的实现：

方案一：

// Java program to demonstrate
// the above function
  
import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.Map;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // Creates a map of charsets
        Map charsets
            = Charset.availableCharsets();
  
        // Iterator to store the type
        Iterator iterator
            = charsets.values().iterator();
  
        // Iterate till we get all the charsets
        while (iterator.hasNext()) {
  
            // Get the next
            Charset all = (Charset)iterator.next();
  
            // Print all the charset which cannot encode
            if (all.canEncode() == false)
                System.out.println(all.displayName());
        }
    }
}

输出：

ISO-2022-CN
x-JISAutoDetect

方案二：

// Java program to demonstrate
// the above function
  
import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.Map;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // Creates a map of charsets
        Map charsets
            = Charset.availableCharsets();
  
        // Iterator to store the type
        Iterator iterator
            = charsets.values().iterator();
  
        // Iterate till we get all the charsets
        while (iterator.hasNext()) {
  
            // Get the next
            Charset all = (Charset)iterator.next();
  
            // Print all the charset which can encode
            if (all.canEncode() == true)
                System.out.print(all.displayName() + " ");
        }
    }
}

输出：

Big5 Big5-HKSCS CESU-8 EUC-JP EUC-KR GB18030 GB2312 GBK IBM-Thai IBM00858 IBM01140 IBM01141 IBM01142 IBM01143 IBM01144 IBM01145 IBM01146 IBM01147 IBM01148 IBM01149 IBM037 IBM1026 IBM1047 IBM273 IBM277 IBM278 IBM280 IBM284 IBM285 IBM290 IBM297 IBM420 IBM424 IBM437 IBM500 IBM775 IBM850 IBM852 IBM855 IBM857 IBM860 IBM861 IBM862 IBM863 IBM864 IBM865 IBM866 IBM868 IBM869 IBM870 IBM871 IBM918 ISO-2022-JP ISO-2022-JP-2 ISO-2022-KR ISO-8859-1 ISO-8859-13 ISO-8859-15 ISO-8859-2 ISO-8859-3 ISO-8859-4 ISO-8859-5 ISO-8859-6 ISO-8859-7 ISO-8859-8 ISO-8859-9 JIS_X0201 JIS_X0212-1990 KOI8-R KOI8-U Shift_JIS TIS-620 US-ASCII UTF-16 UTF-16BE UTF-16LE UTF-32 UTF-32BE UTF-32LE UTF-8 windows-1250 windows-1251 windows-1252 windows-1253 windows-1254 windows-1255 windows-1256 windows-1257 windows-1258 windows-31j x-Big5-HKSCS-2001 x-Big5-Solaris x-COMPOUND_TEXT x-euc-jp-linux x-EUC-TW x-eucJP-Open x-IBM1006 x-IBM1025 x-IBM1046 x-IBM1097 x-IBM1098 x-IBM1112 x-IBM1122 x-IBM1123 x-IBM1124 x-IBM1166 x-IBM1364 x-IBM1381 x-IBM1383 x-IBM300 x-IBM33722 x-IBM737 x-IBM833 x-IBM834 x-IBM856 x-IBM874 x-IBM875 x-IBM921 x-IBM922 x-IBM930 x-IBM933 x-IBM935 x-IBM937 x-IBM939 x-IBM942 x-IBM942C x-IBM943 x-IBM943C x-IBM948 x-IBM949 x-IBM949C x-IBM950 x-IBM964 x-IBM970 x-ISCII91 x-ISO-2022-CN-CNS x-ISO-2022-CN-GB x-iso-8859-11 x-JIS0208 x-Johab x-MacArabic x-MacCentralEurope x-MacCroatian x-MacCyrillic x-MacDingbat x-MacGreek x-MacHebrew x-MacIceland x-MacRoman x-MacRomania x-MacSymbol x-MacThai x-MacTurkish x-MacUkraine x-MS932_0213 x-MS950-HKSCS x-MS950-HKSCS-XP x-mswin-936 x-PCK x-SJIS_0213 x-UTF-16LE-BOM X-UTF-32BE-BOM X-UTF-32LE-BOM x-windows-50220 x-windows-50221 x-windows-874 x-windows-949 x-windows-950 x-windows-iso2022jp

参考： https://docs.oracle.com/javase/9/docs/api/ Java/nio/charset/Charset.html#canEncode–