JDK-5015676 : (reflect) Concrete Type classes could define toString()
  • Type: Enhancement
  • Component: core-libs
  • Sub-Component: java.lang:reflect
  • Affected Version: 5.0
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2004-03-18
  • Updated: 2012-09-28
  • Resolved: 2004-04-16
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Resolved: Release in which this issue/RFE has been resolved.
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Other
5.0 b48Fixed
Related Reports
Duplicate :  
JDK-5026430 - ParameterizedTypeImpl should override toString
Relates :  
JDK-6298888 - Add toGenericString to j.l.Class and getTypeName to j.l.reflect.Type
Description
The Type instances that you get back from e.g. Method.getGenericReturnType() could define useful toString() methods.  At the moment you get the default string, such as "sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl@1e0be38".  Existing reflection classes do define useful toString() methods, e.g. Method.toString() which may return "public abstract java.util.Set T.stringSet()".  Having a useful toString() makes it much easier to produce meaningful exception messages in code that uses reflection ("Could not map " + parameterizedType + " to a factory").

Incidentally Method.toString() could then use getGenericReturnType() and getGenericParameterTypes() instead of getReturnType() and getParameterTypes().
Comments
CONVERTED DATA BugTraq+ Release Management Values COMMIT TO FIX: tiger-beta2 FIXED IN: tiger-beta2 INTEGRATED IN: tiger-b48 tiger-beta2
14-06-2004
WORK AROUND Roll your own, e.g. (incomplete): private static String toString(Type t) { if (t instanceof Class) return ((Class) t).getName(); else if (t instanceof ParameterizedType) { ParameterizedType pt = (ParameterizedType) t; StringBuilder b = new StringBuilder(); b.append(toString(pt.getRaw())).append("<"); Type[] actuals = pt.getActualTypes(); for (int i = 0; i < actuals.length; i++) { if (i > 0) b.append(", "); b.append(toString(actuals[i])); } return b.append(">").toString(); } else return t.toString(); } (The initial version of this workaround contained bugs.)
11-06-2004
PUBLIC COMMENTS The Type instances that you get back from e.g. Method.getGenericReturnType() could define useful toString() methods. At the moment you get the default string, such as "sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl@1e0be38". Existing reflection classes do define useful toString() methods, e.g. Method.toString() which may return "public abstract java.util.Set T.stringSet()". Having a useful toString() makes it much easier to produce meaningful exception messages in code that uses reflection ("Could not map " + parameterizedType + " to a factory").
10-06-2004
SUGGESTED FIX src/share/classes/sun/reflect/generics/reflectiveObjects>sccs sccsdiff -r1.2 -r1.3 ParameterizedTypeImpl.java ------- ParameterizedTypeImpl.java ------- 134a135,174 > > public String toString() { > StringBuilder sb = new StringBuilder(); > > if (ownerType != null) { > if (ownerType instanceof Class) > sb.append(((Class)ownerType).getName()); > else > sb.append(ownerType.toString()); > > sb.append("."); > > if (ownerType instanceof ParameterizedTypeImpl) { > // Find simple name of nested type by removing the > // shared prefix with owner. > sb.append(rawType.getName().replace( ((ParameterizedTypeImpl)ownerType).rawType.getName() + "$", > "")); > } else > sb.append(rawType.getName()); > } else > sb.append(rawType.getName()); > > if (actualTypeArguments != null && > actualTypeArguments.length > 0) { > sb.append("<"); > boolean first = true; > for(Type t: actualTypeArguments) { > if (!first) > sb.append(", "); > if (t instanceof Class) > sb.append(((Class)t).getName()); > else > sb.append(t.toString()); > first = false; > } > sb.append(">"); > } > > return sb.toString(); > } src/share/classes/sun/reflect/generics/reflectiveObjects>sccs sccsdiff -r1.3 -r1.4 TypeVariableImpl.java ------- TypeVariableImpl.java ------- 136a137 > public String toString() {return getName();} src/share/classes/sun/reflect/generics/reflectiveObjects>sccs sccsdiff -r1.3 -r1.4 WildcardTypeImpl.java ------- WildcardTypeImpl.java ------- 104a105 > 161a163,194 > > public String toString() { > Type[] lowerBounds = getLowerBounds(); > Type[] bounds = lowerBounds; > StringBuilder sb = new StringBuilder(); > > if (lowerBounds.length > 0) > sb.append("? super "); > else { > Type[] upperBounds = getUpperBounds(); > if (upperBounds.length > 0 && !upperBounds[0].equals(Object.class) ) { > bounds = upperBounds; > sb.append("? extends "); > } else > return "?"; > } > > assert bounds.length > 0; > > boolean first = true; > for(Type bound: bounds) { > if (!first) > sb.append(" & "); > > first = false; > if (bound instanceof Class) > sb.append(((Class)bound).getName() ); > else > sb.append(bound.toString()); > } > return sb.toString(); > } src/share/classes/sun/reflect/generics/reflectiveObjects>sccs sccsdiff -r1.2 -r1.3 GenericArrayTypeImpl.java ------- GenericArrayTypeImpl.java ------- 47a48,59 > > public String toString() { > Type componentType = getGenericComponentType(); > StringBuilder sb = new StringBuilder(); > > if (componentType instanceof Class) > sb.append(((Class)componentType).getName() ); > else > sb.append(componentType.toString()); > sb.append("[]"); > return sb.toString(); > } ###@###.### 2004-04-12
12-04-2004
EVALUATION A reasonable request; will try to address this for Tiger. ###@###.### 2004-03-18
18-03-2004