edu.umd.cs.findbugs.detect
Class StringConcatenation

java.lang.Object
  extended by edu.umd.cs.findbugs.visitclass.BetterVisitor
      extended by edu.umd.cs.findbugs.visitclass.PreorderVisitor
          extended by edu.umd.cs.findbugs.visitclass.DismantleBytecode
              extended by edu.umd.cs.findbugs.BytecodeScanningDetector
                  extended by edu.umd.cs.findbugs.detect.StringConcatenation
All Implemented Interfaces:
Detector, Constants2, org.apache.bcel.classfile.Visitor, org.apache.bcel.Constants

public class StringConcatenation
extends BytecodeScanningDetector
implements Constants2

Find occurrences of using the String "+" or "+=" operators within a loop. This is much less efficient than creating a dedicated StringBuffer object outside the loop, and then appending to it.

Author:
Dave Brosius, William Pugh

Field Summary
private  BugReporter bugReporter
           
(package private) static int CONSTRUCTED_STRING_ON_STACK
           
private  int createPC
           
private static boolean DEBUG
           
(package private) static int POSSIBLE_CASE
           
private  int registerOnStack
           
private  boolean reportedThisMethod
           
(package private) static int SEEN_APPEND1
           
(package private) static int SEEN_APPEND2
           
(package private) static int SEEN_NEW
           
(package private) static int SEEN_NOTHING
           
private  int state
           
private  int stringSource
           
 
Fields inherited from class edu.umd.cs.findbugs.visitclass.DismantleBytecode
codeBytes, lineNumberTable, M_BR, M_CP, M_INT, M_PAD, M_R, M_UINT, R_DOUBLE, R_FLOAT, R_INT, R_LONG, R_REF, registerKind
 
Fields inherited from interface org.apache.bcel.Constants
AALOAD, AASTORE, ACC_ABSTRACT, ACC_FINAL, ACC_INTERFACE, ACC_NATIVE, ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC, ACC_STATIC, ACC_STRICT, ACC_SUPER, ACC_SYNCHRONIZED, ACC_TRANSIENT, ACC_VOLATILE, ACCESS_NAMES, ACONST_NULL, ALOAD, ALOAD_0, ALOAD_1, ALOAD_2, ALOAD_3, ANEWARRAY, ANEWARRAY_QUICK, ARETURN, ARRAYLENGTH, ASTORE, ASTORE_0, ASTORE_1, ASTORE_2, ASTORE_3, ATHROW, ATTR_CODE, ATTR_CONSTANT_VALUE, ATTR_DEPRECATED, ATTR_EXCEPTIONS, ATTR_INNER_CLASSES, ATTR_LINE_NUMBER_TABLE, ATTR_LOCAL_VARIABLE_TABLE, ATTR_PMG, ATTR_SIGNATURE, ATTR_SOURCE_FILE, ATTR_STACK_MAP, ATTR_SYNTHETIC, ATTR_UNKNOWN, ATTRIBUTE_NAMES, BALOAD, BASTORE, BIPUSH, BREAKPOINT, CALOAD, CASTORE, CHECKCAST, CHECKCAST_QUICK, CLASS_TYPE_NAMES, CONSTANT_Class, CONSTANT_Double, CONSTANT_Fieldref, CONSTANT_Float, CONSTANT_Integer, CONSTANT_InterfaceMethodref, CONSTANT_Long, CONSTANT_Methodref, CONSTANT_NameAndType, CONSTANT_NAMES, CONSTANT_String, CONSTANT_Utf8, CONSTRUCTOR_NAME, CONSUME_STACK, D2F, D2I, D2L, DADD, DALOAD, DASTORE, DCMPG, DCMPL, DCONST_0, DCONST_1, DDIV, DLOAD, DLOAD_0, DLOAD_1, DLOAD_2, DLOAD_3, DMUL, DNEG, DREM, DRETURN, DSTORE, DSTORE_0, DSTORE_1, DSTORE_2, DSTORE_3, DSUB, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, F2D, F2I, F2L, FADD, FALOAD, FASTORE, FCMPG, FCMPL, FCONST_0, FCONST_1, FCONST_2, FDIV, FLOAD, FLOAD_0, FLOAD_1, FLOAD_2, FLOAD_3, FMUL, FNEG, FREM, FRETURN, FSTORE, FSTORE_0, FSTORE_1, FSTORE_2, FSTORE_3, FSUB, GETFIELD, GETFIELD_QUICK, GETFIELD_QUICK_W, GETFIELD2_QUICK, GETSTATIC, GETSTATIC_QUICK, GETSTATIC2_QUICK, GOTO, GOTO_W, I2B, I2C, I2D, I2F, I2L, I2S, IADD, IALOAD, IAND, IASTORE, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, ICONST_M1, IDIV, IF_ACMPEQ, IF_ACMPNE, IF_ICMPEQ, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ICMPLT, IF_ICMPNE, IFEQ, IFGE, IFGT, IFLE, IFLT, IFNE, IFNONNULL, IFNULL, IINC, ILLEGAL_OPCODE, ILLEGAL_TYPE, ILOAD, ILOAD_0, ILOAD_1, ILOAD_2, ILOAD_3, IMPDEP1, IMPDEP2, IMUL, INEG, INSTANCEOF, INSTANCEOF_QUICK, INT2BYTE, INT2CHAR, INT2SHORT, INTERFACES_IMPLEMENTED_BY_ARRAYS, INVOKEINTERFACE, INVOKEINTERFACE_QUICK, INVOKENONVIRTUAL, INVOKENONVIRTUAL_QUICK, INVOKESPECIAL, INVOKESTATIC, INVOKESTATIC_QUICK, INVOKESUPER_QUICK, INVOKEVIRTUAL, INVOKEVIRTUAL_QUICK, INVOKEVIRTUAL_QUICK_W, INVOKEVIRTUALOBJECT_QUICK, IOR, IREM, IRETURN, ISHL, ISHR, ISTORE, ISTORE_0, ISTORE_1, ISTORE_2, ISTORE_3, ISUB, ITEM_Bogus, ITEM_Double, ITEM_Float, ITEM_InitObject, ITEM_Integer, ITEM_Long, ITEM_NAMES, ITEM_NewObject, ITEM_Null, ITEM_Object, IUSHR, IXOR, JSR, JSR_W, KNOWN_ATTRIBUTES, L2D, L2F, L2I, LADD, LALOAD, LAND, LASTORE, LCMP, LCONST_0, LCONST_1, LDC, LDC_QUICK, LDC_W, LDC_W_QUICK, LDC2_W, LDC2_W_QUICK, LDIV, LLOAD, LLOAD_0, LLOAD_1, LLOAD_2, LLOAD_3, LMUL, LNEG, LOOKUPSWITCH, LOR, LREM, LRETURN, LSHL, LSHR, LSTORE, LSTORE_0, LSTORE_1, LSTORE_2, LSTORE_3, LSUB, LUSHR, LXOR, MAJOR, MAJOR_1_1, MAJOR_1_2, MAJOR_1_3, MAX_ACC_FLAG, MAX_BYTE, MAX_CODE_SIZE, MAX_CP_ENTRIES, MAX_SHORT, MINOR, MINOR_1_1, MINOR_1_2, MINOR_1_3, MONITORENTER, MONITOREXIT, MULTIANEWARRAY, MULTIANEWARRAY_QUICK, NEW, NEW_QUICK, NEWARRAY, NO_OF_OPERANDS, NOP, OPCODE_NAMES, POP, POP2, PRODUCE_STACK, PUSH, PUTFIELD, PUTFIELD_QUICK, PUTFIELD_QUICK_W, PUTFIELD2_QUICK, PUTSTATIC, PUTSTATIC_QUICK, PUTSTATIC2_QUICK, RESERVED, RET, RETURN, SALOAD, SASTORE, SHORT_TYPE_NAMES, SIPUSH, STATIC_INITIALIZER_NAME, SWAP, SWITCH, T_ADDRESS, T_ARRAY, T_BOOLEAN, T_BYTE, T_CHAR, T_DOUBLE, T_FLOAT, T_INT, T_LONG, T_OBJECT, T_REFERENCE, T_SHORT, T_UNKNOWN, T_VOID, TABLESWITCH, TYPE_NAMES, TYPE_OF_OPERANDS, UNDEFINED, UNPREDICTABLE, WIDE
 
Fields inherited from interface edu.umd.cs.findbugs.Detector
EXP_PRIORITY, HIGH_PRIORITY, LOW_PRIORITY, NORMAL_PRIORITY
 
Constructor Summary
StringConcatenation(BugReporter bugReporter)
           
 
Method Summary
private  void reset()
           
 void sawOpcode(int seen)
           
private  boolean storeIntoRegister(int seen, int reg)
           
 void visit(org.apache.bcel.classfile.Method obj)
           
 
Methods inherited from class edu.umd.cs.findbugs.BytecodeScanningDetector
getAnalysisContext, getClassContext, report, setAnalysisContext, visitClassContext
 
Methods inherited from class edu.umd.cs.findbugs.visitclass.DismantleBytecode
getBranchFallThrough, getBranchOffset, getBranchTarget, getClassConstantOperand, getConstantRefOperand, getDefaultSwitchOffset, getDottedClassConstantOperand, getDottedSigConstantOperand, getIntConstant, getNameConstantOperand, getPC, getRefConstantOperand, getRefFieldIsStatic, getRegisterOperand, getSigConstantOperand, getStringConstantOperand, getSwitchLabels, getSwitchOffsets, sawClass, sawDouble, sawField, sawFloat, sawIMethod, sawInt, sawLong, sawMethod, sawOffset, sawRegister, sawString, visit
 
Methods inherited from class edu.umd.cs.findbugs.visitclass.PreorderVisitor
asUnsignedByte, getClassName, getConstantPool, getDottedClassName, getDottedFieldSig, getDottedMethodSig, getDottedSuperclassName, getFieldIsStatic, getFieldName, getFieldSig, getFullyQualifiedFieldName, getFullyQualifiedMethodName, getMethod, getMethodName, getMethodSig, getPackageName, getSourceFile, getStringFromIndex, getSuperclassName, getThisClass, visitAfter, visitCode, visitConstantPool, visitingField, visitingMethod, visitInnerClasses, visitJavaClass, visitLineNumberTable, visitLocalVariableTable
 
Methods inherited from class edu.umd.cs.findbugs.visitclass.BetterVisitor
report, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visitCodeException, visitConstantClass, visitConstantDouble, visitConstantFieldref, visitConstantFloat, visitConstantInteger, visitConstantInterfaceMethodref, visitConstantLong, visitConstantMethodref, visitConstantNameAndType, visitConstantString, visitConstantUtf8, visitConstantValue, visitDeprecated, visitExceptionTable, visitField, visitInnerClass, visitLineNumber, visitLocalVariable, visitMethod, visitSignature, visitSourceFile, visitStackMap, visitStackMapEntry, visitSynthetic, visitUnknown
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

DEBUG

private static final boolean DEBUG

SEEN_NOTHING

static final int SEEN_NOTHING
See Also:
Constant Field Values

SEEN_NEW

static final int SEEN_NEW
See Also:
Constant Field Values

SEEN_APPEND1

static final int SEEN_APPEND1
See Also:
Constant Field Values

SEEN_APPEND2

static final int SEEN_APPEND2
See Also:
Constant Field Values

CONSTRUCTED_STRING_ON_STACK

static final int CONSTRUCTED_STRING_ON_STACK
See Also:
Constant Field Values

POSSIBLE_CASE

static final int POSSIBLE_CASE
See Also:
Constant Field Values

bugReporter

private BugReporter bugReporter

reportedThisMethod

private boolean reportedThisMethod

registerOnStack

private int registerOnStack

stringSource

private int stringSource

createPC

private int createPC

state

private int state
Constructor Detail

StringConcatenation

public StringConcatenation(BugReporter bugReporter)
Method Detail

visit

public void visit(org.apache.bcel.classfile.Method obj)
Overrides:
visit in class BetterVisitor

reset

private void reset()

storeIntoRegister

private boolean storeIntoRegister(int seen,
                                  int reg)

sawOpcode

public void sawOpcode(int seen)
Overrides:
sawOpcode in class DismantleBytecode