Java抽象語法樹AST，JCTree 分析

JCTree簡要分析

JCAnnotatedType

被註解的泛型：（註解的Target爲ElementType.TYPE_USE時可註解泛型）

public static class A<T extends @Reality String> {
    
}

• JCAnnotatedType @Reality() String
• annotations (List<JCTree.JCAnnotation>) [0] = (JCAnnotation) @Reality()
• underlyingType (JCExpression) = (JCIdent) String

protected JCAnnotatedType(List<JCTree.JCAnnotation> var1, JCTree.JCExpression var2) {
    Assert.check(var1 != null && var1.nonEmpty());
    this.annotations = var1;
    this.underlyingType = var2;
}

JCAnnotation

註解：@annotationType(args) 例子：@Reality(callSuper = false)

• JCAnnotation @Reality(callSuper = false)
• annotationType (JCTree) = (JCIdent) Reality
• args (List<JCExpression>) = callSuper = false
• attribute (Compound) = @com.juno.annotations.Reality(callSuper=false)

protected JCAnnotation(JCTree.Tag var1, JCTree var2, List<JCTree.JCExpression> var3) {
    this.tag = var1;
    this.annotationType = var2;
    this.args = var3;
}

JCArrayAccess

數組訪問：a[0] = “123”

• index (JCExpression) = 0 (JCLiteral)
• indexed (JCExpression) = a (JCIdent)

protected JCArrayAccess(JCTree.JCExpression var1, JCTree.JCExpression var2) {
    this.indexed = var1;
    this.index = var2;
}

JCArrayTypeTree

數組類型：String[] a = new String[2] 中表達式的右邊：

• elemtype (JCExpression) = String (JCIdent)

二維數組：String[][] a = new String[1][2]解析爲：

• JCArrayTypeTree String[]
• JCIdent String

protected JCArrayTypeTree(JCTree.JCExpression var1) {
    this.elemtype = var1;
}

JCAssert

assert斷言：assert cond : detail

protected JCAssert(JCTree.JCExpression var1, JCTree.JCExpression var2) {
    this.cond = var1;
    this.detail = var2;
}

JCAssign

賦值：lhs = rhs 例如 i = 1

protected JCAssign(JCTree.JCExpression var1, JCTree.JCExpression var2) {
    this.lhs = var1; //左表達式
    this.rhs = var2; //右表達式
}

JCAssignOp

賦值：lhs opcode rhs 例如 i += 1

protected JCAssignOp(JCTree.Tag var1, JCTree var2, JCTree var3, Symbol var4) {
    this.opcode = var1;
    this.lhs = (JCTree.JCExpression)var2;
    this.rhs = (JCTree.JCExpression)var3;
    this.operator = var4;
}

賦值符號opcode的可取值：

/** Assignment operators, of type Assignop.
 */
BITOR_ASG(BITOR),                // |=
BITXOR_ASG(BITXOR),              // ^=
BITAND_ASG(BITAND),              // &=

SL_ASG(SL),                      // <<=
SR_ASG(SR),                      // >>=
USR_ASG(USR),                    // >>>=
PLUS_ASG(PLUS),                  // +=
MINUS_ASG(MINUS),                // -=
MUL_ASG(MUL),                    // *=
DIV_ASG(DIV),                    // /=
MOD_ASG(MOD),                    // %=

JCBinary

將語句分爲二叉結構，例如double i = d + i * f 中第一個JCBinary爲：

• lhs = d
• rhs = i * f
• operator = null
• opcode = PLUS

第二個JCBinary爲：

• lhs = i
• rhs = f
• operator = null
• opcode = MUL

protected JCBinary(JCTree.Tag var1, JCTree.JCExpression var2, JCTree.JCExpression var3, Symbol var4) {
    this.opcode = var1;
    this.lhs = var2;
    this.rhs = var3;
    this.operator = var4;
}

二元運算符opcode的可取值：

/** Binary operators, of type Binary.
 */
OR,                              // ||
AND,                             // &&
BITOR,                           // |
BITXOR,                          // ^
BITAND,                          // &
EQ,                              // ==
NE,                              // !=
LT,                              // <
GT,                              // >
LE,                              // <=
GE,                              // >=
SL,                              // <<
SR,                              // >>
USR,                             // >>>
PLUS,                            // +
MINUS,                           // -
MUL,                             // *
DIV,                             // /
MOD,                             // %

JCBlock

語句塊：{stats} 或 static{stats}（flags = 8L時）

protected JCBlock(long var1, List<JCTree.JCStatement> var3) {
    this.stats = var3;
    this.flags = var1;
}

JCBreak

break語句：break:label

• label 爲標籤名
• target 爲跳轉目標

protected JCBreak(Name var1, JCTree var2) {
    this.label = var1;
    this.target = var2;
}

JCCase

case語句：case pat : stats

protected JCCase(JCTree.JCExpression var1, List<JCTree.JCStatement> var2) {
    this.pat = var1;
    this.stats = var2;
}

JCCatch

catch捕捉異常：catch(param) body

• param 定義異常變量 Exception e
• body 代碼塊

protected JCCatch(JCTree.JCVariableDecl var1, JCTree.JCBlock var2) {
    this.param = var1;
    this.body = var2;
}

JCClassDecl

類的定義：

例子：

@Reality
public class MainActivity extends AppCompatActivity {

    private int kk = 1;

    static {
        kk = 2;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

}

• mods (JCModifiers) = public
• name (Name) = (NameImpl) MainActivity
• extending (JCExpression) = (JCIdent) AppCompatActivity
• implementing (JCExpression) 實現的接口
• defs (List<JCTree>) ：
• defs(1) : JCMethodDecl

  public <init>() {
      super();
  }
  

• defs(2) : JCBlock

  static {
      kk = 2;
  }
  

• defs(3) : JCVariableDecl

  private int kk = 1
  

• defs(4) : JCMethodDecl

  @Override()
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      TextView textView = findViewById(R.id.text);
      Random random = new Random();
  }
  

• sym (ClassSymbol) = com.juno.utils.MainActivity

protected JCClassDecl(JCTree.JCModifiers var1, Name var2, List<JCTree.JCTypeParameter> var3, JCTree.JCExpression var4, List<JCTree.JCExpression> var5, List<JCTree> var6, ClassSymbol var7) {
    this.mods = var1;
    this.name = var2;
    this.typarams = var3;
    this.extending = var4;
    this.implementing = var5;
    this.defs = var6;
    this.sym = var7;
}

JCCompilationUnit

/**
 * Everything in one source file is kept in a TopLevel structure.
 * @param pid The tree representing the package clause. 
 * @param sourcefile The source file name.
 * @param defs All definitions in this file (ClassDef,Import,and Ski
 * @param packge The package it belongs to.
 * @param namedImportScope A scope for all named imports.
 * @param starImportScope A scope for all import-on-demands.
 * @param linelMap Line starting positions,defined only if option-g is set.
 * @param docComments A hashtable that stores all documentation comments indexed by the tree nodes they refer to.defined only if option-s is set.
 * @param endPositions A hashtable that stores ending positions of source ranges indexed by the tree nodes they belong to. Defined only if option-Xjcov is set.
 */
public static class JCCompilationUnit extends JCTree implements CompilationUnitTre{
    public List<JCAnnotation>packageAnnotations:
    public JCExpression pid:
    public List<JCTree>defs:
    public JavaFileObject sourcefile:
    public Package Symbol packge:
    public ImportScope namedImportScope:
    public StarImportScope starImportScope:
    public long flags:
    public Position.LinelMap linelMap=null:
    public Map<JCTree,String>docComments=null:
    public Map<JCTree,Integer>endPositions=null:
    
    protected JCCompilationUnit(List<JCAnnotation>packageAnnotations,
        JCExpression pid,
        List<JCTree>defs,
        JavaFileObject sourcefile,
        Pack ageSymbol packge,
        ImportScope namedImportScope,
        Star ImportScope starImportScope){
            this.packageAnnotations =packageAnnotations:
            this.pid=pid:
            this.defs=defs:
            this.sourcefile=sourcefile:
            this.packge=packge:
            this.namedImportScope=namedImportScope:
            this.starImportScope=starImportScope:
        }
}

JCConditional

三目運算符：cond ? truepart : falsepart 例如 a ? 1 : 3

protected JCConditional(JCTree.JCExpression var1, JCTree.JCExpression var2, JCTree.JCExpression var3) {
    this.cond = var1;
    this.truepart = var2;
    this.falsepart = var3;
}

JCContinue

continue跳過一次循環，與break相似：continue label

protected JCContinue(Name var1, JCTree var2) {
    this.label = var1;
    this.target = var2;
}

JCDoWhileLoop

do-while循環：do{body}while(cond)

protected JCDoWhileLoop(JCTree.JCStatement var1, JCTree.JCExpression var2) {
    this.body = var1;
    this.cond = var2;
}

JCEnhancedForLoop

增強循環：for(var : expr) body

例如：

for (String s : list) {
    print(s);
}

• JCVariableDecl String s 定義字符串變量s
• JCIdent list 遍歷的容器
• JCBlock { print(s); } 遍歷塊

protected JCEnhancedForLoop(JCTree.JCVariableDecl var1, JCTree.JCExpression var2, JCTree.JCStatement var3) {
    this.var = var1;
    this.expr = var2;
    this.body = var3;
}

JCErroneous

Error trees

JCExpression

表達式，賦值、調用方法等都算一個表達式，凡是繼承JCExpression都算一個表達式

JCExpressionStatement

內部封裝了JCExpression，實際上還是個表達式

protected JCExpressionStatement(JCTree.JCExpression var1) {
    this.expr = var1;
}

JCFieldAccess

訪問父類、其他類的方法、變量時：super.onCreate()

• selected (JCIdent) = super
• name (NameImpl) = onCreate

protected JCFieldAccess(JCTree.JCExpression var1, Name var2, Symbol var3) {
    this.selected = var1;
    this.name = var2;
    this.sym = var3;
}

JCForloop

for循環：

• for (init; cond; step) {body}（body爲JCBlock）
• for (init; cond; step) body（body爲JCExpressionStatement）

protected JCForLoop(List<JCTree.JCStatement> var1, JCTree.JCExpression var2, List<JCTree.JCExpressionStatement> var3, JCTree.JCStatement var4) {
    this.init = var1;
    this.cond = var2;
    this.step = var3;
    this.body = var4;
}

JCFunctionalExpression

函數式表達式：lambda(JCLambda)和method reference(JCMemberReference)繼承於JCFunctionalExpression

JCIdent

出現在表達式中的變量名、調用的方法名以及類名等，例子如下（按順序）：

• Reality 類（註解）
• AppCompatActivity 類
• String 類
• Override 類
• Bundle 類
• super super和this都是一個JcIdent
• savedInstanceState 調用變量的名字
• setContentView 方法
• R 類
• textView 調用變量的名字
• findViewById 方法
• R類

@Reality //JCIdent Reality ClassSymbol com.juno.annotations.Reality
//JCIdent AppCompatActivity ClassSymbol android.support.v7.app.AppCompatActivity
public class MainActivity extends AppCompatActivity  {

    //JCIdent String ClassSymbol java.lang.String
    private static final String TAG = "MainActivity";
    
    private int kk = 1;

    @Override //JCIdent Override ClassSymbol java.lang.Override
    //JCIdent Bundle ClassSymbol android.os.Bundle
    protected void onCreate(Bundle savedInstanceState) {
    
        //JCIdent super
        //JCIdent savedInstanceState
        super.onCreate(savedInstanceState);
        
        //JCIdent setContentView 
        //JCIdent R
        setContentView(R.layout.activity_main);
        
        TextView textView;
        //JCIdent textView
        //JCIdent findViewById
        //JCIdent R
        textView = findViewById(R.id.text);

        int i = 0;
        int j = 1;
        
        //JCIdent i
        //JCIdent j
        i = j * 3 + 2;
        
        //JCIdent this
        this.kk = 0;
    }

}

其中TextView textView;這一句是變量定義語句（JCVariableDecl），該語句的vartype屬性實際上也是個JCIdent：

• JCVariableDecl TextView textView
• name (Name) = textView (NameImpl)
• vartype (JCExpression) = TextView (JCIdent)

JCIf

if判斷語句：if(condition) {thenpart} else {elsepart}

protected JCIf(JCTree.JCExpression var1, JCTree.JCStatement var2, JCTree.JCStatement var3) {
    this.cond = var1;
    this.thenpart = var2;
    this.elsepart = var3;
}

JCImport

import語句：

• import qulid
• static (if staticImport) import qulid

protected JCImport(JCTree var1, boolean var2) {
    this.qualid = var1;
    this.staticImport = var2;
}

JCinstanceOf

instanceof語句：expr instanceof clazz，例如textView instanceof View：

• JCInstanceOf textView instanceof View
• clazz (JCTree) = (JCIdent) View
• expr (JCExpression) = (JCIdent) textView

protected JCInstanceOf(JCTree.JCExpression var1, JCTree var2) {
    this.expr = var1;
    this.clazz = var2;
}

JCLabeledStatement

帶有標籤的語句：label : body

protected JCLabeledStatement(Name var1, JCTree.JCStatement var2) {
    this.label = var1;
    this.body = var2;
}

JCLambda

lambda表達式：此處表達式主體只有一句表達式

textView.setOnClickListener(v -> v.setVisibility(View.INVISIBLE));

• JCLambda (v)->v.setVisibility(View.INVISIBLE) （表達式整體）
• params (List<JCTree.JCVariableDecl>) = (List) /*missing*/ v （參數定義列表）
• body (JCTree) = (JCMethodInvocation) v.setVisibility(View.INVISIBLE) （主體）
• canCompleteNormally (Boolean) = true （未知）
• paramKind (ParameterKind) = IMPLICIT （參數類型隱形/明確）
• getBodyKind() (BodyKind) = EXPRESSION （主體是表達式還是塊）

當主體變爲語句塊時：

textView.setOnClickListener(v -> {
    v.setVisibility(View.VISIBLE);
});

• body (JCTree) = (JCBlock) {v.setVisibility(View.VISIBLE);}
• getBodyKind() (BodyKind) = STATEMENT

當參數v指明類型爲View時：

textView.setOnClickListener((View v) -> v.setVisibility(View.INVISIBLE));

• paramKind (ParameterKind) = IMPLICIT （參數類型明確）

JCLiteral

表示常量：int a = 1

• typetag (TypeTag) = INT
• value (Object) = (Integer) 1

protected JCLiteral(TypeTag var1, Object var2) {
    this.typetag = var1;
    this.value = var2;
}

typetag的可選值有：

INT : int
LONG : long
FLOAT : float
DOUBLE : double
CHAR : char
CLASS : String
BOT : null

JCMemberReference

lambda表達式中的方法引用：expr::name

例子：new B(“123”).setObjectUtil(ObjectUtil::new);

• JCMemberReference ObjectUtil::new
• mode (ReferenceMode) = NEW
• name (Name) = (NameImpl)
• expr (JCExpression) = (JCIdent) ObjectUtil

例子：new B(“123”).setObjectUtil(this::util);

• JCMemberReference this::util
• mode (ReferenceMode) = INVOKE
• name (Name) = (NameImpl) util
• expr (JCExpression) = (JCIdent) this

protected JCMemberReference(ReferenceMode var1, Name var2, JCTree.JCExpression var3, List<JCTree.JCExpression> var4) {
    this.mode = var1;
    this.name = var2;
    this.expr = var3;
    this.typeargs = var4;
}

JCMethodDecl

方法的定義：

例子：

@Reality
private static <T extends String> int print(@NonNull final String s) throws RuntimeException {
    Log.e(TAG, s);
    return 1;
}

• mods (JCModifiers) = @Reality() private static
• name (Name) = (NameImpl) print
• restype (JCExpression) = (JCPrimitiveTypeTree) int
• typarams (JCTypeParameter) = T extends String
• recvparam = null
• params (List<JCVariableDecl>) [0] = @NonNull() final String s
• thrown (JCExpression) = (JCIdent) RuntimeException
• body (JCBlock) = {
  Log.e(TAG, s);
  return 1;
  }
• defaultVaule (JCExpression) = null
• sym (MethodSymbol) = print(java.lang.String)

例子：

@Reality
@interface B {
    int value() default 1;
}

• name (Name) = (NameImpl) value
• restype (JCExpression) = (JCPrimitiveTypeTree) int
• typarams (JCTypeParameter) 泛型列表爲空
• recvparam = null
• params (List<JCVariableDecl>) 參數定義爲空
• thrown (JCExpression) 拋出列表爲空
• body (JCBlock) 方法體爲空
• defaultVaule (JCExpression) = (JCLiteral) 1
• sym (MethodSymbol) = value()

protected JCMethodDecl(JCTree.JCModifiers var1, Name var2, JCTree.JCExpression var3, List<JCTree.JCTypeParameter> var4, JCTree.JCVariableDecl var5, List<JCTree.JCVariableDecl> var6, List<JCTree.JCExpression> var7, JCTree.JCBlock var8, JCTree.JCExpression var9, MethodSymbol var10) {
    this.mods = var1;
    this.name = var2;
    this.restype = var3;
    this.typarams = var4;
    this.params = var6;
    this.recvparam = var5;
    this.thrown = var7;
    this.body = var8;
    this.defaultValue = var9;
    this.sym = var10;
}

JCMethodinvocation

方法執行語句： meth(args)

例子：notNull(before)

• meth (JCExpression) = (JCIdent) notNull
• args (List<JCExpression>) = (JCIdent) before

例子：proxy.invoke(target, method, args)

• meth (JCExpression) = (JCFieldAccess) proxy.invoke
• args (List<JCExpression>) = (JCIdent) target, method, args

protected JCMethodInvocation(List<JCTree.JCExpression> var1, JCTree.JCExpression var2, List<JCTree.JCExpression> var3) {
    this.typeargs = var1 == null ? List.nil() : var1;
    this.meth = var2;
    this.args = var3;
}

JCModifiers

類、變量、方法等的修飾符和註解：例如：

@Reality private static final String TAG = "MainActivity";

• flags (long) = 26L （2L | 8L | 16L）
• annotations (List<JCTree.JCAnnotation>) = @Reality()

protected JCModifiers(long var1, List<JCTree.JCAnnotation> var3) {
    this.flags = var1;
    this.annotations = var3;
}

flags的可取值：

1L : public
2L : private
4L : protected
8L : static
16L : final
32L : synchronized
64L : volatile
128L : transient
256L : native
1024L : abstract
2048L : strictfp
8589934592L : default

方法默認flags不爲default，而是0L

JCNewArray

new數組：

例子：String[] s = new String[]{“123”,“456”};

• JCNewArray new String[]{“123”, “456”}
• elemtype (JCExpression) = (JCIdent) String
• dims (List<JCTree.JCExpression>) 空
• elems (List<JCTree.JCExpression>) [0] = (JCLiteral) “123”
• elems (List<JCTree.JCExpression>) [1] = (JCLiteral) “456”

例子：B[][] b = new B[3][4];

• JCNewArray new B[3][4]
• elemtype (JCExpression) = (JCIdent) B
• dims (List<JCTree.JCExpression>) [0] = (JCLiteral) 3
• dims (List<JCTree.JCExpression>) [1] = (JCLiteral) 4
• elems (List<JCTree.JCExpression>) 空

protected JCNewArray(JCTree.JCExpression var1, List<JCTree.JCExpression> var2, List<JCTree.JCExpression> var3) {
    this.elemtype = var1;
    this.dims = var2;
    this.annotations = List.nil();
    this.dimAnnotations = List.nil();
    this.elems = var3;
}

JCNewClass

new一個對象：

例子：new B(“123”)

• JCNewClass new B(“123”)
• clazz (JCExpression) = (JCTypeApply) B
• args (List<JCTree.JCExpression>) [0] = (JCLiteral) “123”

protected JCNewClass(JCTree.JCExpression var1, List<JCTree.JCExpression> var2, JCTree.JCExpression var3, List<JCTree.JCExpression> var4, JCTree.JCClassDecl var5) {
    this.encl = var1;
    this.typeargs = var2 == null ? List.nil() : var2;
    this.clazz = var3;
    this.args = var4;
    this.def = var5;
}

JCParens

括號：(expr) 存在於if、計算式、synchronized中

protected JCParens(JCTree.JCExpression var1) {
    this.expr = var1;
}

JCPrimitiveTypeTree

基本類型：

基本類型的賦值：int i = 0 ：

• typetag = INT

方法的返回值：void print(String s) {Log.e(TAG, s);}

• typetag = VOID

protected JCPrimitiveTypeTree(TypeTag var1) {
    this.typetag = var1;
}

typetag可選值：

INT : int
LONG : long
FLOAT : float
DOUBLE : double
DOOLEAN : boolean
CHAR : char
BYTE : byte
short : short
VOID : void

JCReturn

return語句：return expr

protected JCReturn(JCTree.JCExpression var1) {
    this.expr = var1;
}

JCSkip

空操作，即一個無效的分號 “;”

JCStatement

聲明：凡是繼承JCStatement都是一個聲明，在JCBlock中拿到的都是JCStatement，想在JCBlock中拿到JCExpression就用JCExpressionStatement

JCSWitch

switch語句：switch(selector) {cases}

protected JCSwitch(JCTree.JCExpression var1, List<JCTree.JCCase> var2) {
    this.selector = var1;
    this.cases = var2;
}

JCSynchronized

synchronized同步鎖：synchronized(lock){block}

protected JCSynchronized(JCTree.JCExpression var1, JCTree.JCBlock var2) {
    this.lock = var1;
    this.body = var2;
}

JCThrow

拋出異常：throw expr

protected JCThrow(JCTree.JCExpression var1) {
    this.expr = var1;
}

JCTry

try塊：try body catchers finally finalizer

protected JCTry(List<JCTree> var1, JCTree.JCBlock var2, List<JCTree.JCCatch> var3, JCTree.JCBlock var4) {
    this.body = var2;
    this.catchers = var3;
    this.finalizer = var4;
    this.resources = var1;
}

resources不知道是什麼

JCTypeApply

泛型參數：List list = new ArrayList<>()

對於List list：

• clazz (JCExpression) = (JCIdent) List
• arguments (List<JCTree.JCExpression>) [0] = (JCIdent) String

對於new ArrayList<>()：

• clazz (JCExpression) = (JCIdent) ArrayList
• arguments (List<JCTree.JCExpression>) = empty

protected JCTypeApply(JCTree.JCExpression var1, List<JCTree.JCExpression> var2) {
    this.clazz = var1;
    this.arguments = var2;
}

JCTypeCast

類型轉換：(clazz)expr

例子：View textView = ((TextView) findViewById(R.id.text));

• JCTypeCast (TextView)findViewById(R.id.text)
• clazz (JCTree) = (JCIdent) TextView
• expr (JCExpression) = (JCMethodInvocation) findViewById(R.id.text)

例子：TextView t = (TextView) textView;

• JCTypeCast (TextView)textView
• clazz (JCTree) = (JCIdent) TextView
• expr (JCExpression) = (JCIdent) textView

protected JCTypeCast(JCTree var1, JCTree.JCExpression var2) {
    this.clazz = var1;
    this.expr = var2;
}

JCTypelntersection

unknown

泛型交叉：

public static class A<T extends String & Runnable> {

}

protected JCTypeIntersection(List<JCTree.JCExpression> var1) {
    this.bounds = var1;
}

JCTypeParameter

類的泛型定義：class

• JCTypeParameter @Anno() T extends View
• name (Name) = (NameImpl) T
• bounds (List<JCTree.JCExpression>) [0] = (JCIdent) View
  JCAnnotation @MainActivity.A()

protected JCTypeParameter(Name var1, List<JCTree.JCExpression> var2, List<JCTree.JCAnnotation> var3) {
    this.name = var1;
    this.bounds = var2;
    this.annotations = var3;
}

JCTypeUnion

catch塊中異常的或定義：T1 | T2 | … Tn

try{
    ...
}catch (ClassCastException | ArrayIndexOutOfBoundsException e){
    ...
}

• JCTypeUnion ClassCastException | ArrayIndexOutOfBoundsException
• alternatives (List<JCTree.JCExpression>) [0] = (JCIdent) ClassCastException
• alternatives (List<JCTree.JCExpression>) [1] = (JCIdent) ArrayIndexOutOfBoundsException

protected JCTypeUnion(List<JCTree.JCExpression> var1) {
    this.alternatives = var1;
}

JCUnary

一元運算語句：i++中

• opcode = POSTINC
• arg = i （實際是JCIdent類型）

protected JCUnary(JCTree.Tag var1, JCTree.JCExpression var2) {
    this.opcode = var1;
    this.arg = var2;
}

/** Unary operators, of type Unary.
 */
POS,                             // +
NEG,                             // -
NOT,                             // !
COMPL,                           // ~
PREINC,                          // ++ _
PREDEC,                          // -- _
POSTINC,                         // _ ++
POSTDEC,                         // _ --

JCVariableDecl

定義變量： mods vartype name = init

例子：final TextView textView = findViewById(R.id.text);

• JCVariableDecl final TextView textView = findViewById(R.id.text)
• mods (JCModifiers) = final
• name (Name) = (NameImpl) textView
• vartype (JCExpression) = (JCIdent) TextView
• init (JCExpression) = (JCMethodInvocation) findViewById(R.id.text)

例子：double i = 1 + 2 * 3;

• JCVariableDecl double i = 1 + 2 * 3
• name (Name) = (NameImpl) i
• vartype (JCExpression) = （JCPrimitiveTypeTree) double
• init (JCExpression) = (JCBinary) 1 + 2 * 3

例子：int k = cond ? 0 : 1;

• JCVariableDecl int k = cond ? 0 : 1
• init (JCExpression) = (JCConditional) cond ? 0 : 1

protected JCVariableDecl(JCTree.JCModifiers var1, Name var2, JCTree.JCExpression var3, JCTree.JCExpression var4, VarSymbol var5) {
    this.mods = var1;
    this.name = var2;
    this.vartype = var3;
    this.init = var4;
    this.sym = var5;
}

JCWhileLoop

while循環：while(cond){body}

爲什麼body不是Statement List或Block？

protected JCWhileLoop(JCTree.JCExpression var1, JCTree.JCStatement var2) {
    this.cond = var1;
    this.body = var2;
}

JCWildcard

泛型中的"?"通配符：Class<? super String> c;

• JCWildcard ? super String
• kind (TypeBoundKind) = ? super
• inner (JCTree) = (JCIdent) String

protected JCWildcard(JCTree.TypeBoundKind var1, JCTree var2) {
    var1.getClass();
    this.kind = var1;
    this.inner = var2;
}