如何解决嵌套五个条件运算符
| 是否可以在Java中嵌套5个以上的“条件运算符”。我问是因为似乎在尝试编译此代码时会导致编译器异常：public Object getValue() {
return
number != null ? number :
string != null ? string :
bool != null ? bool :
date != null ? date :
list != null ? list :
null;
}
public Object getValue() {
return
number != null ? number :
string != null ? string :
bool != null ? bool :
date != null ? date :
// list != null ? list :
null;
}
解决方法
我转载了您的错误（在Mac上使用Sun JDK 1.6.0_24）。我将您的课程简化为：
import java.util.ArrayList;
import java.util.Date;
public class Test3 {
private Number number;
private String string;
private Boolean bool; // Replace Boolean with Object,and it compiles!
private Date date;
private ArrayList<String> list; // Replace ArrayList with List,and it
// compiles!
public Object getValue() {
return number != null ? number :
string != null ? string :
bool != null ? bool :
date != null ? date :
list != null ? list :
null;
}
}
An exception has occurred in the compiler (1.6.0_24). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.AssertionError
at com.sun.tools.javac.jvm.Code$State.forceStackTop(Code.java:1688)
at com.sun.tools.javac.jvm.Gen.visitConditional(Gen.java:1679)
at com.sun.tools.javac.tree.JCTree$JCConditional.accept(JCTree.java:1021)
at com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:818)
at com.sun.tools.javac.jvm.Gen.visitConditional(Gen.java:1678)
at com.sun.tools.javac.tree.JCTree$JCConditional.accept(JCTree.java:1021)
at com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:818)
at com.sun.tools.javac.jvm.Gen.visitConditional(Gen.java:1678)
at com.sun.tools.javac.tree.JCTree$JCConditional.accept(JCTree.java:1021)
at com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:818)
at com.sun.tools.javac.jvm.Gen.visitReturn(Gen.java:1626)
at com.sun.tools.javac.tree.JCTree$JCReturn.accept(JCTree.java:1138)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:665)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:700)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:686)
at com.sun.tools.javac.jvm.Gen.genStats(Gen.java:737)
at com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:1013)
at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:665)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:700)
at com.sun.tools.javac.jvm.Gen.genMethod(Gen.java:893)
at com.sun.tools.javac.jvm.Gen.visitMethodDef(Gen.java:866)
at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:639)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:665)
at com.sun.tools.javac.jvm.Gen.genClass(Gen.java:2198)
at com.sun.tools.javac.main.JavaCompiler.genCode(JavaCompiler.java:617)
at com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1289)
at com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1259)
at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:765)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:730)
at com.sun.tools.javac.main.Main.compile(Main.java:353)
at com.sun.tools.javac.main.Main.compile(Main.java:279)
at com.sun.tools.javac.main.Main.compile(Main.java:270)
at com.sun.tools.javac.Main.compile(Main.java:69)
at com.sun.tools.javac.Main.main(Main.java:54)
public class Test {
Object number=null,string=null,bool=null,date=null,list=null;
public Object getValue() {
return
number != null ? number :
string != null ? string :
bool != null ? bool :
date != null ? date :
list != null ? list :
null;
}
}
public static void main (String[] args) throws java.lang.Exception
{
Object number = null;
Object string = null;
Object list = null;
Object bool = null;
Object date = null;
Object o =
number != null ? number :
string != null ? string :
bool != null ? bool :
date != null ? date :
list != null ? list :
null;
}
public class Holder implements Serializable {
Serializable value;
public void setValue(Number value) {
this.value = value;
}
public void setValue(String value) {
this.value = value;
}
public void setValue(Boolean value) {
this.value = value;
}
public void setValue(Date value) {
this.value = value;
}
public <L extends List & Serializable> void setValue(L value) {
this.value = value;
}
public Serializable getValue() {
return value;
}
}
public class TestHit
{
protected final String fSymbol;
protected final long fTime;
protected final USDollars fBasePrice;
public TestHit(String aSymbol,long aTime,int aBasePrice)
{
fSymbol = aSymbol;
fTime = aTime;
fBasePrice = new USDollars(aBasePrice);
}
public Object field(int aIndex)
{
return (aIndex == 0)? fSymbol
: (aIndex == 1)? fTime
: (aIndex == 2)? fBasePrice
: (aIndex == 3)? new Integer(4) // comment out this line and it compiles
: \"?\";
}
}
final class USDollars
implements Comparable<USDollars> // comment out this line and it compiles
{
private int cents;
public USDollars() { this(0); }
public USDollars(int cents) { this.cents = cents; }
public USDollars(int dollars,int cents) { this(cents + 100*dollars); }
public int cents() { return cents; }
// @Override
public int compareTo(USDollars other) { return this.cents - other.cents; }
}
public Object field(int aIndex)
{
if (aIndex == 2)
return fBasePrice;
return (aIndex == 0)? fSymbol
: (aIndex == 1)? fTime
: (aIndex == 3)? new Integer(4) // comment out this line and it compiles
: \"?\";
}
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