如何在Java 9中调试JShell?
JShell 是一种 REPL 工具,允许运行代码片段,而无需将它们放入类中。此工具提供了一种在 Java 中评估声明、语句和表达式的方法,无需创建 main() strong> 方法来测试代码的某些部分。
命令"/debug"可用于显示调试信息 JShell工具实现。一旦我们输入“/debug”命令,调试模式就会开启。启用调试模式并输入诸如简单加法或简单字符串之类的内容后,它将打印如下。
Example-1
<strong>jshell> /debug | Debugging on</strong> <strong>jshell> 5+3 Compiling: 5+3 Kind: EXPRESSION_STATEMENT -- 5 + 3; compileAndLoad [Unit($1)] ++setCompilationInfo() Snippet:VariableKey($1)#11-5+3 package REPL; import java.io.*;import java.math.*;import java.net.*;import java.nio.file.*;import java.util.*; import java.util.concurrent.*;import java.util.function.*;import java.util.prefs.*; import java.util.regex.*;import java.util.stream.*;class $JShell $11 { public static int $1; public static Object do_it$() throws Throwable { return $1 = 5+3; } } -- diags: [] setStatus() Snippet:VariableKey($1)#11-5+3 - status: VALID compileAndLoad ins = [Unit($1)] -- legit = [Unit($1)] Compiler generating class REPL.$JShell$11 compileAndLoad [Unit($1)] -- deps: [] success: true recordCompilation: Snippet:VariableKey($1)#11-5+3 -- status VALID, unresolved [] $1 ==> 8</strong>
示例 2
<strong>jshell> /debug | Debugging on jshell> String s = "Adithya" Compiling: String s = "Adithya"; Kind: VARIABLE -- String s = "Adithya" compileAndLoad [Unit(s)] ++setCompilationInfo() Snippet:VariableKey(s)#12-String s = "Adithya"; package REPL; import java.io.*;import java.math.*;import java.net.*;import java.nio.file.*;import java.util.*; import java.util.concurrent.*;import java.util.function.*;import java.util.prefs.*; import java.util.regex.*;import java.util.stream.*;import static REPL.$JShell$11.$1; class $JShell$12 { public static String s; public static Object do_it$() throws Throwable { String s_ = "Adithya"; return s = s_; } } -- diags: [] setStatus() Snippet:VariableKey(s)#12-String s = "Adithya"; - status: VALID compileAndLoad ins = [Unit(s)] -- legit = [Unit(s)] Compiler generating class REPL.$JShell$12 compileAndLoad [Unit(s)] -- deps: [] success: true recordCompilation: Snippet:VariableKey(s)#12-String s = "Adithya"; -- status VALID, unresolved [] s ==> "Adithya"</strong>
如果我们想要“关闭”调试模式,请再次键入” /debug”同一会话的命令。
<strong>jshell> /debug | Debugging off</strong>
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