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WIP: Fix PMD rule LiteralsFirstInComparisons for compareTo* and contentEquals #448

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WIP: Fix PMD rule LiteralsFirstInComparisons for compareTo* and contentEquals #448

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1f33b73
Use new `J.SwitchExpression` constructor
knutwannheden Jan 23, 2025
b38ff0a
Use new `J.SwitchExpression` constructor
knutwannheden Jan 23, 2025
3725b4a
Merge remote-tracking branch 'f/Fix-PMD-rule-LiteralsFirstInCompariso…
Jan 25, 2025
52676bf
tmp fix invertConditional_compareToIgnoreCase
Jan 25, 2025
883f9cf
wip
Jan 25, 2025
1d3c8de
tmp fix
Jan 25, 2025
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32 changes: 16 additions & 16 deletions src/main/java/org/openrewrite/staticanalysis/EqualsAvoidsNull.java
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
*/
package org.openrewrite.staticanalysis;

import org.apache.commons.lang3.ObjectUtils;
import org.jspecify.annotations.Nullable;
import org.openrewrite.*;
import org.openrewrite.java.JavaIsoVisitor;
Expand Down Expand Up @@ -54,24 +55,23 @@ public Duration getEstimatedEffortPerOccurrence() {

@Override
public TreeVisitor<?, ExecutionContext> getVisitor() {
JavaIsoVisitor<ExecutionContext> replacementVisitor = new JavaIsoVisitor<ExecutionContext>() {
@Override
public J visit(@Nullable Tree tree, ExecutionContext ctx) {
if (tree instanceof JavaSourceFile) {
JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
EqualsAvoidsNullStyle style = cu.getStyle(EqualsAvoidsNullStyle.class);
if (style == null) {
style = Checkstyle.equalsAvoidsNull();
return Preconditions.check(
// new UsesMethod<>("java.lang.String *quals*(..)"),
new UsesMethod<>("java.lang.String *(..)"),
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Hi @timtebeek,
I need help finding a better regex for equals and compareTo. The current one is just a temporary fix—it might work, but it's inefficient.

new JavaIsoVisitor<ExecutionContext>() {
@Override
public J visit(@Nullable Tree tree, ExecutionContext ctx) {
if (tree instanceof JavaSourceFile) {
JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
return new EqualsAvoidsNullVisitor<>(
ObjectUtils.defaultIfNull(cu.getStyle(EqualsAvoidsNullStyle.class),
Checkstyle.equalsAvoidsNull()))
.visitNonNull(cu, ctx);
}
//noinspection DataFlowIssue
return (J) tree;
}
return new EqualsAvoidsNullVisitor<>(style).visitNonNull(cu, ctx);
}
//noinspection DataFlowIssue
return (J) tree;
}
};
return Preconditions.check(
new UsesMethod<>("java.lang.String *quals*(..)"),
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I noticed this by accident while wondering why the recipe wasn’t applied. I think it would be better to prioritize a functional approach—putting the most important things first. In a functional style, it’s easier to see and understand the flow right away.

Thanks for considering this!

replacementVisitor
);
}
}
9 changes: 7 additions & 2 deletions src/main/java/org/openrewrite/staticanalysis/EqualsAvoidsNullVisitor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -49,15 +49,18 @@ public class EqualsAvoidsNullVisitor<P> extends JavaVisitor<P> {
private static final String JAVA_LANG_STRING = "java.lang.String ";
private static final MethodMatcher EQUALS = new MethodMatcher(JAVA_LANG_STRING + "equals(java.lang.Object)");
private static final MethodMatcher EQUALS_IGNORE_CASE = new MethodMatcher(JAVA_LANG_STRING + "equalsIgnoreCase(java.lang.String)");
private static final MethodMatcher COMPARE_TO = new MethodMatcher(JAVA_LANG_STRING + "compareTo(java.lang.String)");
private static final MethodMatcher COMPARE_TO_IGNORE_CASE = new MethodMatcher(JAVA_LANG_STRING + "compareToIgnoreCase(java.lang.String)");
private static final MethodMatcher CONTENT_EQUALS = new MethodMatcher(JAVA_LANG_STRING + "contentEquals(java.lang.CharSequence)");

EqualsAvoidsNullStyle style;

@Override
public J visitMethodInvocation(J.MethodInvocation method, P p) {
J.MethodInvocation m = (J.MethodInvocation) super.visitMethodInvocation(method, p);
boolean stringComparisonMethod = isStringComparisonMethod(m);
if (m.getSelect() != null && !(m.getSelect() instanceof J.Literal) &&
isStringComparisonMethod(m) && hasCompatibleArgument(m)) {
stringComparisonMethod && hasCompatibleArgument(m)) {

maybeHandleParentBinary(m);

Expand Down Expand Up @@ -90,7 +93,9 @@ private boolean hasCompatibleArgument(J.MethodInvocation m) {
private boolean isStringComparisonMethod(J.MethodInvocation methodInvocation) {
return EQUALS.matches(methodInvocation) ||
(!style.getIgnoreEqualsIgnoreCase() && EQUALS_IGNORE_CASE.matches(methodInvocation)) ||
CONTENT_EQUALS.matches(methodInvocation);
CONTENT_EQUALS.matches(methodInvocation) ||
COMPARE_TO.matches(methodInvocation) ||
COMPARE_TO_IGNORE_CASE.matches(methodInvocation);
}

private void maybeHandleParentBinary(J.MethodInvocation m) {
Expand Down
61 changes: 61 additions & 0 deletions src/test/java/org/openrewrite/staticanalysis/EqualsAvoidsNullTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,58 @@ public class A {
);
}

@DocumentExample
@Test
void invertConditional_compareTo() {
rewriteRun(
//language=java
java(
"""
public class A {
{
String s = null;
if(s.compareTo("test")) {}
}
}
""",
"""
public class A {
{
String s = null;
if("test".compareTo(s)) {}
}
}
"""
)
);
}

@DocumentExample
@Test
void invertConditional_compareToIgnoreCase() {
rewriteRun(
//language=java
java(
"""
public class A {
{
String s = null;
if(s.compareToIgnoreCase("test")) {}
}
}
""",
"""
public class A {
{
String s = null;
if("test".compareToIgnoreCase(s)) {}
}
}
"""
)
);
}

@Test
void removeUnnecessaryNullCheck() {
rewriteRun(
Expand Down Expand Up @@ -447,6 +499,15 @@ public class A {
System.out.println(s.compareToIgnoreCase("test"));
}
}
""",
"""
public class A {
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I’m not sure why we don’t have a second comparison method here—you guys probably know better. Looking at the code, it seems like the goal is to avoid an NPE.

This test was the only one failing, which caught my attention, so I decided to conclude it and ask the team for their thoughts.

Thanks!

{
String s = null;
System.out.println("test".compareTo(s));
System.out.println("test".compareToIgnoreCase(s));
}
}
"""
)
);
Expand Down
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