diff --git a/src/main/java/haidnor/jvm/core/JavaExecutionEngine.java b/src/main/java/haidnor/jvm/core/JavaExecutionEngine.java
index 904c6ec..4dfb713 100644
--- a/src/main/java/haidnor/jvm/core/JavaExecutionEngine.java
+++ b/src/main/java/haidnor/jvm/core/JavaExecutionEngine.java
@@ -26,10 +26,19 @@ import java.util.Map;
 @Slf4j
 public class JavaExecutionEngine {
 
+    /**
+     * 执行  public static void main(String[] args) 方法
+     */
     public static void callMainMethod(KlassMethod klassMethod) {
         callMethod(null, klassMethod);
     }
 
+    /**
+     * 执行普通方法
+     *
+     * @param lastFrame   方法调用者的栈帧
+     * @param klassMethod 方法元信息
+     */
     public static void callMethod(Frame lastFrame, KlassMethod klassMethod) {
         JVMThread jvmThread = JvmThreadHolder.get();
         Frame newFrame = new Frame(jvmThread, klassMethod);
@@ -80,26 +89,28 @@ public class JavaExecutionEngine {
         CodeStream codeStream = frame.getCodeStream();
         while (codeStream.available() > 0) {
             Instruction instruction = InstructionFactory.creatInstruction(codeStream);
-            log.debug("{}│> {}", blank, instruction);
             instructionMap.put(instruction.index(), instruction);
+            log.debug("{}│> {}", blank, instruction);
         }
 
         log.debug("{}├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌", blank);
 
-        // 执行方法中的字节码指令 tip:(int pc, 相当于程序计数器, 记录当前执行到的字节码指令的”行号“)
+        // 执行方法中的字节码指令
+        // 提示: 变量 pc 相当于程序计数器, 记录当前执行到的字节码指令的"行号"
         for (int pc = 0; pc < frame.getCodeLength(); ) {
             Instruction instruction = instructionMap.get(pc);
             log.debug("{}│ {}", blank, instruction);
             try {
-                // 执行栈帧
+                // 执行字节码指令
                 instruction.execute(frame);
+                // 若为 return 系列指令则结束当前栈帧
                 if (instruction instanceof RETURN || instruction instanceof ARETURN || instruction instanceof DRETURN || instruction instanceof FRETURN || instruction instanceof IRETURN) {
                     break;
                 }
                 // 程序计数器值增加. 指向下一次执行的字节码行号
                 pc += instruction.offSet();
             }
-            // 捕获执行栈帧运行抛出的异常
+            // 捕获执行字节码指令抛出的异常
             catch (Exception exception) {
                 // 从类元信息中获取异常表
                 CodeException[] exceptionTable = frame.getMethod().getCode().getExceptionTable();
@@ -107,9 +118,9 @@ public class JavaExecutionEngine {
                 // handlerPC 是从异常表中获取的处理异常的字节码行号 (如果查询不到就会一直为 null. 代表方法无异常处理代码)
                 Integer handlerPC = null;
                 for (CodeException codeException : exceptionTable) {
-                    if (codeException.getStartPC() <= pc & pc <= codeException.getEndPC()) {
+                    if (codeException.getStartPC() <= pc && pc <= codeException.getEndPC()) {
+                        // 异常类型 (0 代表捕获所有类型的异常)
                         int catchType = codeException.getCatchType();
-                        // catchType == 0 代表捕获所有类型的异常
                         if (catchType == 0) {
                             frame.push(new StackValue(Const.T_OBJECT, exception));
                             handlerPC = codeException.getHandlerPC();
@@ -128,7 +139,7 @@ public class JavaExecutionEngine {
                     // 将程序计数器跳转到处理异常的字节码指令上
                     pc = handlerPC;
                 } else {
-                    // 方法无异常处理. 异常退出.结束栈帧
+                    // 方法无异常处理,结束栈帧. 将异常抛给调用者处理
                     log.debug("{}└──────────────────[{}] No Exception Handler Return!", blank, stackSize);
                     throw exception;
                 }
@@ -141,9 +152,9 @@ public class JavaExecutionEngine {
 
     /**
      * 计算绘画 jvm 线程栈 debug 日志信息的空格
-     * 用于表现栈的调用关系.
+     * 用于表现栈的调用关系
      *
-     * @param stackSize 当前 JVM 栈的深度
+     * @param stackSize 当前 JVM 线程栈的栈帧数量
      */
     private static String getDebugStackInfoBlank(int stackSize) {
         StringBuilder blank = new StringBuilder();
diff --git a/src/main/java/haidnor/jvm/instruction/Instruction.java b/src/main/java/haidnor/jvm/instruction/Instruction.java
index 98cca0d..7007ffd 100644
--- a/src/main/java/haidnor/jvm/instruction/Instruction.java
+++ b/src/main/java/haidnor/jvm/instruction/Instruction.java
@@ -8,7 +8,7 @@ import haidnor.jvm.util.CodeStream;
  */
 public abstract class Instruction {
     /**
-     * 指令坐在 code 数组中的索引下标
+     * 指令在字节码 code 数组中的索引下标 (可以理解为指令的行号)
      */
     private final int index;
 
@@ -21,6 +21,11 @@ public abstract class Instruction {
         this.index = codeStream.index();
     }
 
+    /**
+     * 执行执行
+     *
+     * @param frame 当前 JVM 线程栈的栈帧
+     */
     public abstract void execute(Frame frame);
 
     public int index() {
diff --git a/src/main/java/haidnor/jvm/runtime/JVMThread.java b/src/main/java/haidnor/jvm/runtime/JVMThread.java
index 9b50eac..573b78b 100644
--- a/src/main/java/haidnor/jvm/runtime/JVMThread.java
+++ b/src/main/java/haidnor/jvm/runtime/JVMThread.java
@@ -26,6 +26,9 @@ public class JVMThread extends Thread {
         this.stack.pop();
     }
 
+    /**
+     * 获取 JVM 线程栈的栈帧数量
+     */
     public int stackSize() {
         return this.stack.size();
     }