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[BUG] Transcompiling error to iOS #2922

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jsfan3 opened this issue Sep 14, 2019 · 3 comments
Closed

[BUG] Transcompiling error to iOS #2922

jsfan3 opened this issue Sep 14, 2019 · 3 comments
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@jsfan3
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@jsfan3 jsfan3 commented Sep 14, 2019

I have the suspect that the following test case demonstrates a transcompiling error from Java to the iOS native language. The following code works as expected on Android and on Simulator, but it fails with a NullPointerException on iOS because of the line result[0] += character;.
Maybe my split code is not the best, but it should be valid: please correct me if I'm wrong.

public void start() {
        if(current != null){
            current.show();
            return;
        }
        Form hi = new Form("Test Split", BoxLayout.y());
        String text = "Abc-123456-7890";
        String[] tokens = split(text, '-');
        hi.add(new Label("Original string: " + text));
        hi.add(new Label("Token 1: " + tokens[0]));
        hi.add(new Label("Token 2: " + tokens[1]));
        hi.show();
    }
    /**
     * Similar to tokenize, but in this case it splits the string always in two
     * tokens, according to the first occurence of the given separator.
     *
     * @param text
     * @param separator
     * @return a string array of two tokens: if the saparator is not found, the
     * first token is equal to the given text and the second token is an empty
     * string
     */
    public static String[] split(String text, Character separator) {
        String[] result = {"", ""};
        boolean separatorFound = false;
        for (Character character : text.toCharArray()) {
            if (!separatorFound && character.equals(separator)) {
                separatorFound = true;
                continue;
            }
            if (!separatorFound) {
                result[0] += character;
            } else {
                result[1] += character;
            }
        }
        return result;
    }

Android screenshot:
Screenshot_20190914-105504

iOS crash report log:

[EDT] 0:0:0,4 - Codename One revisions: 7dd4e7d08b3442d90959477ee52a5ae8c4361b29

[EDT] 0:0:0,8 - Exception: java.lang.NullPointerException - null
java.lang.NullPointerException
    at net_informaticalibera_tests_MyApplication.split:93
    at net_informaticalibera_tests_MyApplication.start:56
    at net_informaticalibera_tests_MyApplicationStub.run:31
    at com_codename1_ui_Display.processSerialCalls:1298
    at com_codename1_ui_Display.mainEDTLoop:1093
    at com_codename1_ui_RunnableWrapper.run:120
    at com_codename1_impl_CodenameOneThread.run:176
    at java_lang_Thread.runImpl:153
[EDT] 0:0:0,9 - Exception in TestSplit version 1.0
[EDT] 0:0:0,9 - OS ios
[EDT] 0:0:0,9 - Error java.lang.NullPointerException: null
[EDT] 0:0:0,9 - Before the first form!
[EDT] 0:0:0,10 - Exception: java.lang.NullPointerException - null
java.lang.NullPointerException
    at net_informaticalibera_tests_MyApplication.split:93
    at net_informaticalibera_tests_MyApplication.start:56
    at net_informaticalibera_tests_MyApplicationStub.run:31
    at com_codename1_ui_Display.processSerialCalls:1298
    at com_codename1_ui_Display.mainEDTLoop:1093
    at com_codename1_ui_RunnableWrapper.run:120
    at com_codename1_impl_CodenameOneThread.run:176
    at java_lang_Thread.runImpl:153
[Network Thread] 0:0:0,447 - Failed to parse expires date sun 13-sep-20 08:45:20 gmt for cookie
@ramsestom

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@ramsestom ramsestom commented Sep 14, 2019

String[] result = new String[] {"", ""};

@jsfan3

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@jsfan3 jsfan3 commented Sep 14, 2019

@ramsestom Thank you for the suggestion, but in Java 8 String[] result = new String[] {"", ""}; and String[] result = {"", ""}; is exactly the same thing, without any difference. To demonstrate that, I checked that in both cases the bytecode produced by the compiler is the same, that is the following.

(Note the nice optimization of the compiler that makes my split method a lot more efficient replacing my += operator between strings with the use of StringBuilder)

  public static java.lang.String[] split(java.lang.String, java.lang.Character);
    Code:
       0: iconst_2
       1: anewarray     #32                 // class java/lang/String
       4: dup
       5: iconst_0
       6: ldc           #33                 // String
       8: aastore
       9: dup
      10: iconst_1
      11: ldc           #33                 // String
      13: aastore
      14: astore_2
      15: iconst_0
      16: istore_3
      17: aload_0
      18: invokevirtual #34                 // Method java/lang/String.toCharArray:()[C
      21: astore        4
      23: aload         4
      25: arraylength
      26: istore        5
      28: iconst_0
      29: istore        6
      31: iload         6
      33: iload         5
      35: if_icmpge     125
      38: aload         4
      40: iload         6
      42: caload
      43: invokestatic  #17                 // Method java/lang/Character.valueOf:(C)Ljava/lang/Character;
      46: astore        7
      48: iload_3
      49: ifne          66
      52: aload         7
      54: aload_1
      55: invokevirtual #35                 // Method java/lang/Character.equals:(Ljava/lang/Object;)Z
      58: ifeq          66
      61: iconst_1
      62: istore_3
      63: goto          119
      66: iload_3
      67: ifne          96
      70: new           #20                 // class java/lang/StringBuilder
      73: dup
      74: invokespecial #21                 // Method java/lang/StringBuilder."<init>":()V
      77: aload_2
      78: iconst_0
      79: dup2_x1
      80: aaload
      81: invokevirtual #23                 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      84: aload         7
      86: invokevirtual #36                 // Method java/lang/StringBuilder.append:(Ljava/lang/Object;)Ljava/lang/StringBuilder;
      89: invokevirtual #24                 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
      92: aastore
      93: goto          119
      96: new           #20                 // class java/lang/StringBuilder
      99: dup
     100: invokespecial #21                 // Method java/lang/StringBuilder."<init>":()V
     103: aload_2
     104: iconst_1
     105: dup2_x1
     106: aaload
     107: invokevirtual #23                 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
     110: aload         7
     112: invokevirtual #36                 // Method java/lang/StringBuilder.append:(Ljava/lang/Object;)Ljava/lang/StringBuilder;
     115: invokevirtual #24                 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
     118: aastore
     119: iinc          6, 1
     122: goto          31
     125: aload_2
     126: areturn
@codenameone codenameone added this to the Version 7.0 milestone Sep 15, 2019
@shannah shannah closed this in 50443a5 Sep 16, 2019
@jsfan3

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@jsfan3 jsfan3 commented Sep 16, 2019

@shannah Thank you!

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