Fix an NPE (#579)

When mainParameter is null (which is the default), calling getMainParameterValue()/getMainParameterDescription() throws an NPE because it tries to access a field on a null object. Co-authored-by: Markus KARG <[email protected]>
cbeust · Apr 11, 2024 · 35e8bd6 · 35e8bd6
1 parent 38acef9
commit 35e8bd6
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Showing 2 changed files with 18 additions and 3 deletions.
diff --git a/src/main/java/com/beust/jcommander/JCommander.java b/src/main/java/com/beust/jcommander/JCommander.java
@@ -1036,8 +1036,9 @@ private void initMainParameterValue(String arg) {
 
     public String getMainParameterDescription() {
         if (descriptions == null) createDescriptions();
-        return mainParameter.annotation != null ? mainParameter.annotation.description()
-                : null;
+    return mainParameter == null
+        ? null
+        : mainParameter.annotation != null ? mainParameter.annotation.description() : null;
     }
 
     /**
@@ -1322,7 +1323,7 @@ public List<ParameterDescription> getParameters() {
      * @return the main parameter description or null if none is defined.
      */
     public ParameterDescription getMainParameterValue() {
-        return mainParameter.description;
+        return mainParameter == null ? null : mainParameter.description;
     }
 
     private void p(String string) {

diff --git a/src/test/java/com/beust/jcommander/JCommanderTest.java b/src/test/java/com/beust/jcommander/JCommanderTest.java
@@ -1438,6 +1438,20 @@ class Args {
                 .build();
     }
 
+    @Test
+    public void noMainParameter() {
+        class Args {
+            @Parameter(names = "-f")
+            private int f;
+        }
+        Args args = new Args();
+        JCommander jcommander =
+            JCommander.newBuilder().addObject(args).args(new String[] {"-f", "1"}).build();
+        Assert.assertNull(jcommander.getMainParameter());
+        Assert.assertNull(jcommander.getMainParameterDescription());
+        Assert.assertNull(jcommander.getMainParameterValue());
+    }
+
     @Test
     public void mainWithConverter() {