今天同事遇到的split的有趣情況
測試原始碼如下:

import org.junit.Test;
 @Test
    public void StringSplit(){
        System.out.println("雙引號之間是被split的字元");
        System.out.println();

        String str1 = "";
        String[] strArr1  =  str1.split(",");
        System.out.println(" 0個逗號: ");
        System.out.println
 
(" \""+str1+"\".split(\",\").length="+strArr1.length);
        System.out.println();


        String str2 = ",,,,";
        String[] strArr2  =  str2.split(",");
        System.out.println(" N(N>0)個純逗號:");
        System.out.println("\""+str2+"\".split(\",\").length="+strArr2.length);
        System.
 
out.println();

        String str3 = ",A,,A,";
        String[] strArr3  =  str3.split(",");
        System.out.println(" 4個純逗號,最後一個字元在最後一個逗號之前,最後逗號後是空字元:");
        System.out.println("\""+str3+"\".split(\",\").length="+strArr3.length);
        System.out.println();
        
        String str4 = ",,,,A"
 
;
        String[] strArr4  =  str4.split(",");
        System.out.println(" 4個逗號結尾是字元(本例是A)");
        System.out.println(":\""+str4+"\".split(\",\").length="+strArr4.length);
        System.out.println();


        String str5 =",,A,,A,,";
        String[] strArr5  =  str5.split(",");
        System.out.println(" 6個純逗號,最後一個字元在倒數第二個逗號之前,最後逗號後是空字元");
        System.out.println("\""+str5+"\".split(\",\").length="+strArr5.length);
        System.out.println();

        String str7 =",,,A,,,A, , ,, ";
        String[] strArr7  =  str7.split(",");
        System.out.println(" 10個逗號,最終結尾是空格:");
        System.out.println("\""+str7+"\".split(\",\").length="+strArr7.length);
        System.out.println();

        String str8 =",,,,,,,,,, ";
        String[] strArr8  =  str8.split(",");
        System.out.println(" 10個逗號,最終結尾是空格:");
        System.out.println("\""+str8+"\".split(\",\").length="+strArr8.length);
    }

輸出結果:
0個逗號:
“”.split(",").length=1

N(N>0)個純逗號:
“,”.split(",").length=0

4個純逗號,最後一個字元在最後一個逗號之前,最後逗號後是空字元:
“,A,A,”.split(",").length=4

4個逗號結尾是字元(本例是A)
:",A".split(",").length=5

6個純逗號,最後一個字元在倒數第二個逗號之前,最後逗號後是空字元
“,A,A,”.split(",").length=5

10個逗號,最終結尾是空格:
“,A,A, , , “.split(”,”).length=11

10個逗號,最終結尾是空格:
“, “.split(”,”).length=11

結論:如果想要獲得逗號+1數量的陣列,最後一個逗號後一定要有字元,空格也可以.