feat(java): support for Java.NoSuchElementException

Author: nedpals

error_templates/java/java.go

@@ -16,6 +16,7 @@ func LoadErrorTemplates(errorTemplates *lib.ErrorTemplates) {
 	errorTemplates.MustAdd(java.Language, ArithmeticException)
 	errorTemplates.MustAdd(java.Language, NegativeArraySizeException)
 	errorTemplates.MustAdd(java.Language, StringIndexOutOfBoundsException)
+	errorTemplates.MustAdd(java.Language, NoSuchElementException)
 
 	// Compile time
 	errorTemplates.MustAdd(java.Language, PublicClassFilenameMismatchError)

error_templates/java/no_such_element_exception.go

@@ -0,0 +1,91 @@
+package java
+
+import (
+	"fmt"
+
+	lib "github.com/nedpals/errgoengine"
+)
+
+type noSuchElementExceptionCtx struct {
+	parentNode      lib.SyntaxNode
+	grandParentNode lib.SyntaxNode
+}
+
+var NoSuchElementException = lib.ErrorTemplate{
+	Name:    "NoSuchElementException",
+	Pattern: runtimeErrorPattern("java.util.NoSuchElementException", ""),
+	OnAnalyzeErrorFn: func(cd *lib.ContextData, m *lib.MainError) {
+		ctx := noSuchElementExceptionCtx{}
+		query := `(method_invocation object: (_) name: (identifier) @fn-name arguments: (argument_list) (#eq? @fn-name "next")) @call`
+		for q := m.Nearest.Query(query); q.Next(); {
+			if q.CurrentTagName() != "fn-name" {
+				continue
+			}
+
+			node := q.CurrentNode()
+			// nCtx.ArrayExprNode = node
+			// m.Nearest = node.ChildByFieldName("dimensions").NamedChild(0)
+			m.Nearest = node
+		}
+
+		ctx.parentNode = m.Nearest.Parent() // expr -> method_invocation
+
+		// get grandparent node
+		ctx.grandParentNode = ctx.parentNode.Parent()
+		if !ctx.grandParentNode.IsNull() {
+			if ctx.grandParentNode.Type() == "expression_statement" || ctx.grandParentNode.Type() == "variable_declarator" {
+				ctx.grandParentNode = ctx.grandParentNode.Parent()
+			}
+		}
+
+		m.Context = ctx
+	},
+	OnGenExplainFn: func(cd *lib.ContextData, gen *lib.ExplainGenerator) {
+		gen.Add("This error occurs when attempting to retrieve an element from an empty collection using an iterator.")
+	},
+	OnGenBugFixFn: func(cd *lib.ContextData, gen *lib.BugFixGenerator) {
+		ctx := cd.MainError.Context.(noSuchElementExceptionCtx)
+		// TODO: detect the statements that are using the variable to expand the position range of the if statement
+
+		gen.Add("Check if the iterator has next elements before calling `next()`", func(s *lib.BugFixSuggestion) {
+			step := s.AddStep("Ensure that the iterator has elements before attempting to retrieve the next one.")
+			gpLocation := ctx.grandParentNode.Location()
+			parentName := ctx.parentNode.ChildByFieldName("object").Text()
+			// TODO: detect the statements that are using the variable to expand the position range of the if statement
+			wrapWithCondStatement(
+				step,
+				cd.MainError.Document,
+				"if",
+				fmt.Sprintf("%s.hasNext()", parentName),
+				gpLocation,
+				false,
+			)
+
+			wrapWithCondStatement(
+				step,
+				cd.MainError.Document,
+				"else",
+				"",
+				lib.Location{
+					StartPos: gpLocation.EndPos,
+					EndPos:   gpLocation.EndPos,
+				},
+				true,
+			)
+
+			space := getSpace(
+				cd.MainError.Document,
+				gpLocation.StartPos.Line, 0, gpLocation.StartPos.Column, true)
+
+			step.AddFix(lib.FixSuggestion{
+				NewText: indentSpace(space, 1) + `System.out.println("No elements in the list.")`,
+				StartPosition: lib.Position{
+					Line: gpLocation.EndPos.Line - 2,
+				},
+				EndPosition: lib.Position{
+					Line: gpLocation.EndPos.Line - 2,
+				},
+			})
+		})
+	},
+}

error_templates/java/test_files/no_such_element_exception/Main.java

@@ -0,0 +1,11 @@
+import java.util.*;
+
+public class Main {
+    public static void main(String[] args) {
+        List<String> myList = new ArrayList<>();
+        Iterator<String> iterator = myList.iterator();
+        // Attempting to get an element from an empty list
+        String element = iterator.next();
+        System.out.println(element);
+    }
+}

error_templates/java/test_files/no_such_element_exception/test.txt

@@ -0,0 +1,33 @@
+template: "Java.NoSuchElementException"
+---
+Exception in thread "main" java.util.NoSuchElementException
+	at java.base/java.util.ArrayList$Itr.next(ArrayList.java:1052)
+	at Main.main(Main.java:8)
+===
+template: "Java.NoSuchElementException"
+---
+# NoSuchElementException
+This error occurs when attempting to retrieve an element from an empty collection using an iterator.
+```
+        // Attempting to get an element from an empty list
+        String element = iterator.next();
+                                  ^^^^
+        System.out.println(element);
+    }
+```
+## Steps to fix
+### Check if the iterator has next elements before calling `next()`
+Ensure that the iterator has elements before attempting to retrieve the next one.
+```diff
+        Iterator<String> iterator = myList.iterator();
+        // Attempting to get an element from an empty list
+-         String element = iterator.next();
++         if (iterator.hasNext()) {
++             String element = iterator.next();
++         } else {
++             System.out.println("No elements in the list.")
++         }
++
+        System.out.println(element);
+    }
+```