public class IdentifyProblemsInCode {
public void howToDoInJava_method3() {
System.out.println("how to do");
if (true) {
return;
}
System.out.println("in java");
}
}
<Block BeginColumn="41" BeginLine="4" EndColumn="5" EndLine="10" FindBoundary="false" Image="" SingleLine="false" containsComment="false">
<BlockStatement Allocation="false" BeginColumn="9" BeginLine="5" EndColumn="40" EndLine="5" FindBoundary="false" Image="" SingleLine="true">
<Statement BeginColumn="9" BeginLine="5" EndColumn="40" EndLine="5" FindBoundary="false" Image="" SingleLine="true">
<StatementExpression BeginColumn="9" BeginLine="5" EndColumn="39" EndLine="5" FindBoundary="false" Image="" SingleLine="true">
<PrimaryExpression BeginColumn="9" BeginLine="5" EndColumn="39" EndLine="5" FindBoundary="false" Image="" SingleLine="true">
<PrimaryPrefix BeginColumn="9" BeginLine="5" EndColumn="26" EndLine="5" FindBoundary="false" Image="" SingleLine="true" SuperModifier="false" ThisModifier="false">
<Name BeginColumn="9" BeginLine="5" EndColumn="26" EndLine="5" FindBoundary="false" Image="System.out.println" SingleLine="true"/>
</PrimaryPrefix>
<PrimarySuffix ArgumentCount="1" Arguments="true" ArrayDereference="false" BeginColumn="27" BeginLine="5" EndColumn="39" EndLine="5" FindBoundary="false" Image="" SingleLine="true">
<Arguments ArgumentCount="1" BeginColumn="27" BeginLine="5" EndColumn="39" EndLine="5" FindBoundary="false" Image="" SingleLine="true">
<ArgumentList BeginColumn="28" BeginLine="5" EndColumn="38" EndLine="5" FindBoundary="false" Image="" SingleLine="true">
<Expression BeginColumn="28" BeginLine="5" EndColumn="38" EndLine="5" FindBoundary="false" Image="" SingleLine="true">
<PrimaryExpression BeginColumn="28" BeginLine="5" EndColumn="38" EndLine="5" FindBoundary="false" Image="" SingleLine="true">
<PrimaryPrefix BeginColumn="28" BeginLine="5" EndColumn="38" EndLine="5" FindBoundary="false" Image="" SingleLine="true" SuperModifier="false" ThisModifier="false">
<Literal BeginColumn="28" BeginLine="5" CharLiteral="false" EndColumn="38" EndLine="5" FindBoundary="false" FloatLiteral="false" Image=""how to do"" IntLiteral="false" SingleCharacterStringLiteral="false" SingleLine="true" StringLiteral="true"/>
</PrimaryPrefix>
</PrimaryExpression>
</Expression>
</ArgumentList>
</Arguments>
</PrimarySuffix>
</PrimaryExpression>
</StatementExpression>
</Statement>
</BlockStatement>
<BlockStatement Allocation="false" BeginColumn="9" BeginLine="6" EndColumn="9" EndLine="8" FindBoundary="false" Image="" SingleLine="false">
<Statement BeginColumn="9" BeginLine="6" EndColumn="9" EndLine="8" FindBoundary="false" Image="" SingleLine="false">
<IfStatement BeginColumn="9" BeginLine="6" Else="false" EndColumn="9" EndLine="8" FindBoundary="false" Image="" SingleLine="false">
<Expression BeginColumn="13" BeginLine="6" EndColumn="16" EndLine="6" FindBoundary="false" Image="" SingleLine="true">
<PrimaryExpression BeginColumn="13" BeginLine="6" EndColumn="16" EndLine="6" FindBoundary="false" Image="" SingleLine="true">
<PrimaryPrefix BeginColumn="13" BeginLine="6" EndColumn="16" EndLine="6" FindBoundary="false" Image="" SingleLine="true" SuperModifier="false" ThisModifier="false">
<Literal BeginColumn="13" BeginLine="6" CharLiteral="false" EndColumn="16" EndLine="6" FindBoundary="false" FloatLiteral="false" Image="" IntLiteral="false" SingleCharacterStringLiteral="false" SingleLine="true" StringLiteral="false">
<BooleanLiteral BeginColumn="13" BeginLine="6" EndColumn="16" EndLine="6" FindBoundary="false" Image="" SingleLine="true" True="true"/>
</Literal>
</PrimaryPrefix>
</PrimaryExpression>
</Expression>
<Statement BeginColumn="19" BeginLine="6" EndColumn="9" EndLine="8" FindBoundary="false" Image="" SingleLine="false">
<Block BeginColumn="19" BeginLine="6" EndColumn="9" EndLine="8" FindBoundary="false" Image="" SingleLine="false" containsComment="false">
<BlockStatement Allocation="false" BeginColumn="13" BeginLine="7" EndColumn="19" EndLine="7" FindBoundary="false" Image="" SingleLine="true">
<Statement BeginColumn="13" BeginLine="7" EndColumn="19" EndLine="7" FindBoundary="false" Image="" SingleLine="true">
<ReturnStatement BeginColumn="13" BeginLine="7" EndColumn="19" EndLine="7" FindBoundary="false" Image="" SingleLine="true"/>
</Statement>
</BlockStatement>
</Block>
</Statement>
</IfStatement>
</Statement>
</BlockStatement>
<BlockStatement Allocation="false" BeginColumn="9" BeginLine="9" EndColumn="38" EndLine="9" FindBoundary="false" Image="" SingleLine="true">
<Statement BeginColumn="9" BeginLine="9" EndColumn="38" EndLine="9" FindBoundary="false" Image="" SingleLine="true">
<StatementExpression BeginColumn="9" BeginLine="9" EndColumn="37" EndLine="9" FindBoundary="false" Image="" SingleLine="true">
<PrimaryExpression BeginColumn="9" BeginLine="9" EndColumn="37" EndLine="9" FindBoundary="false" Image="" SingleLine="true">
<PrimaryPrefix BeginColumn="9" BeginLine="9" EndColumn="26" EndLine="9" FindBoundary="false" Image="" SingleLine="true" SuperModifier="false" ThisModifier="false">
<Name BeginColumn="9" BeginLine="9" EndColumn="26" EndLine="9" FindBoundary="false" Image="System.out.println" SingleLine="true"/>
</PrimaryPrefix>
<PrimarySuffix ArgumentCount="1" Arguments="true" ArrayDereference="false" BeginColumn="27" BeginLine="9" EndColumn="37" EndLine="9" FindBoundary="false" Image="" SingleLine="true">
<Arguments ArgumentCount="1" BeginColumn="27" BeginLine="9" EndColumn="37" EndLine="9" FindBoundary="false" Image="" SingleLine="true">
<ArgumentList BeginColumn="28" BeginLine="9" EndColumn="36" EndLine="9" FindBoundary="false" Image="" SingleLine="true">
<Expression BeginColumn="28" BeginLine="9" EndColumn="36" EndLine="9" FindBoundary="false" Image="" SingleLine="true">
<PrimaryExpression BeginColumn="28" BeginLine="9" EndColumn="36" EndLine="9" FindBoundary="false" Image="" SingleLine="true">
<PrimaryPrefix BeginColumn="28" BeginLine="9" EndColumn="36" EndLine="9" FindBoundary="false" Image="" SingleLine="true" SuperModifier="false" ThisModifier="false">
<Literal BeginColumn="28" BeginLine="9" CharLiteral="false" EndColumn="36" EndLine="9" FindBoundary="false" FloatLiteral="false" Image=""in java"" IntLiteral="false" SingleCharacterStringLiteral="false" SingleLine="true" StringLiteral="true"/>
</PrimaryPrefix>
</PrimaryExpression>
</Expression>
</ArgumentList>
</Arguments>
</PrimarySuffix>
</PrimaryExpression>
</StatementExpression>
</Statement>
</BlockStatement>
</Block>
Xpath表达式：
// MethodDeclaration [count（ResultType）= 1] / Block [（。// BlockStatement / Statement / IfStatement / Expression / PrimaryExpression / PrimaryPrefix / Literal / BooleanLiteral / @ True）=＆＃39; true＆＃39;和 （.// BlockStatement/Statement/IfStatement/Statement/Block/BlockStatement/Statement/ReturnStatement/@SingleLine）=＆＃39; true＆＃39;] / BlockStatement [last（）]
如何编写xpath表达式来查找死代码
在上面的代码System.out.println("in java");中，此行是死代码，如何使用xpath表达式找到此块
答案 0 :(得分：3)
XPath用于选择XML。这是用于解析Java或任何其他编程语言的错误工具。此外，死代码确定需要可达性计算，通常被认为是语义分析，而不仅仅是语法分析。你甚至不能在XPath中做到这一点。
更新：您现在已在PDM中以XML格式发布了abstract syntax tree。这比让XPath违反原始Java代码更好，但它仍然不足以进行完全可达性分析。您需要PDM的内容是control flow graph，这似乎不是PDM的功能。