parseInt returns double in rhino

Question

I have this JavaScript file (Rhino 1.7R4).

importPackage(java.io);
importPackage(java.lang);
importPackage(java.util);

var reader = new BufferedReader( new InputStreamReader(System['in']) );

var line = reader.readLine();
var tok = new java.util.StringTokenizer(line);

var A = Integer.parseInt(tok.nextToken());
var B = Integer.parseInt(tok.nextToken());
var C = Integer.parseInt(tok.nextToken());

// System.out.printf( "A=%d, B=%d, C=%d\n", A, B, C );
System.out.printf( "A=%f, B=%f, C=%f\n", A, B, C );

When I uncomment first printf - I'm getting

A=Exception in thread "main" org.mozilla.javascript.WrappedException: Wrapped java.util.IllegalFormatConversionException: d != java.lang.Double
        at org.mozilla.javascript.Context.throwAsScriptRuntimeEx(Context.java:1754)
        at org.mozilla.javascript.MemberBox.invoke(MemberBox.java:148)
        at org.mozilla.javascript.NativeJavaMethod.call(NativeJavaMethod.java:225)
        at org.mozilla.javascript.optimizer.OptRuntime.callN(OptRuntime.java:52)
        at test._c_script_0(Unknown Source)
        at test.call(Unknown Source)
        at org.mozilla.javascript.ContextFactory.doTopCall(ContextFactory.java:394)
        at org.mozilla.javascript.ScriptRuntime.doTopCall(ScriptRuntime.java:3091)
        at test.call(Unknown Source)
        at test.exec(Unknown Source)
        at org.mozilla.javascript.optimizer.OptRuntime$1.run(OptRuntime.java:218)
        at org.mozilla.javascript.Context.call(Context.java:489)
        at org.mozilla.javascript.ContextFactory.call(ContextFactory.java:504)
        at org.mozilla.javascript.optimizer.OptRuntime.main(OptRuntime.java:206)
        at test.main(Unknown Source)
Caused by: java.util.IllegalFormatConversionException: d != java.lang.Double
        at java.util.Formatter$FormatSpecifier.failConversion(Unknown Source)
        at java.util.Formatter$FormatSpecifier.printInteger(Unknown Source)
        at java.util.Formatter$FormatSpecifier.print(Unknown Source)
        at java.util.Formatter.format(Unknown Source)
        at java.io.PrintStream.format(Unknown Source)
        at java.io.PrintStream.printf(Unknown Source)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at org.mozilla.javascript.MemberBox.invoke(MemberBox.java:126)
        ... 13 more

score 3 · Accepted Answer · answered Apr 30 '14 at 00:22

3

That's a reault of the JavaScript type system. All numbers in JavaScript are doubles, so while `Integer.parseInt("4.5") returns 4, it needs to be converted to 4.0 for JavaScript.

Fortunately, 64-bit doubles have enough precision to represent any 32-bit int exactly, so on the JavaScript side you typically don't need to worry about it. But the Java object behind the value is always a Double and gets converted automatically when it needs to be. But since System.out.printf takes arguments of type Object it has to be passed as is.

answered Apr 30 '14 at 00:22

Matthew Crumley

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So I have to handle int arithmetic, for example integer division by my own? let say A is 5 B is 2, so I would expect that 5/2 is 2 and not 2.5 – Betlista Apr 30 '14 at 06:12
Ok, thanks I didn't expect that - here is the question about the division - http://stackoverflow.com/questions/4228356/integer-division-in-javascript – Betlista Apr 30 '14 at 06:18
1

Right, all division in JavaScript is floating point (really everything except the bit-wise and, or, complement, and xor operators which convert their operands to 32-bit ints first). – Matthew Crumley Apr 30 '14 at 13:18

parseInt returns double in rhino

1 Answers1