JAVA.CLASS.CAST : Risky Class Cast (Java)

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CodeSonar^® 9.2p0

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JAVA.CLASS.CAST : Risky Class Cast (Java)

要旨

Java checks explicit type downcasts at runtime. If they do not hold, a runtime exception is thrown. This checker verifies that casts will be satisfied at runtime, so that they will never throw an exception.

プロパティ

例

public class TestCasts {
  private Object f;
  private Object g = "hi";

  public void m1(Object o) {
    if (((String) o).startsWith("hello"))       // "Risky Class Cast (Java)" warning issued here
      System.out.println("nice to meet you");
  }

  public void m2(String s, Object o) {
    if (((String) o).startsWith("hello"))       // "Risky Class Cast (Java)" warning issued here
      System.out.println("nice to meet you");
  }

  public void m3(String s, Object o) {
    if (((String) wrap(o)).startsWith("hello")) // "Risky Class Cast (Java)" warning issued here if JAVA_ANALYSIS_PEDANTIC_MODE=Yes
      System.out.println("nice to meet you");
  }

  public void m4() {
    if (((String) f).startsWith("hello"))       // "Risky Class Cast (Java)" warning issued here if JAVA_ANALYSIS_PEDANTIC_MODE=Yes
      System.out.println("nice to meet you");
  }

  public void m5() {
    if (((String) g).startsWith("hello"))                    // ok: safe cast
      System.out.println("nice to meet you");
  }

  private Object wrap(Object o) {
    return o;
  }

  public void caller1() {
    m1("hi");
    m1(this);
  }

  public void caller2() {
    m2("ciao", "hello");
    m2("come stai", "how are you?");
  }

  public void caller3() {
    m3("ciao", "hello");
    m3("come stai", f = new Object());
  }
}

解決法

For each classcast warning, verify that all types that will ever reach that program point are assignable to the type used for the cast.

関連のある設定ファイルパラメータ

設定ファイルの以下のパラメータがこのワーニングクラスのチェックに影響します。