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<li>String conversions
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There are five <i>conversion contexts</i> in which conversion expressions can occur. Each context allows conversions in some of the above-named categories but not others. The conversion contexts are:<p>
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<li>Assignment conversion <a href="Concepts.doc.html#19674">(&#167;2.6.6)</a>, which converts the type of an expression to the type of a specified variable. The conversions permitted for assignment are limited in such a way that assignment conversion never causes an exception.
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<li>Method invocation conversion <a href="Concepts.doc.html#19685">(&#167;2.6.7)</a>, which is applied to each argument in a method or constructor invocation, and, except in one case, performs the same conversions that assignment conversion does. Method invocation conversion never causes an exception.
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<li>Casting conversion <a href="Concepts.doc.html#18168">(&#167;2.6.8)</a>, which converts the type of an expression to a type explicitly specified by a cast operator. It is more inclusive than assignment or method invocation conversion, allowing any specific conversion other than a string conversion, but certain casts to a reference type may cause an exception at run time.
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<li>String conversion, which allows any type to be converted to type <code>String</code> <a href="Concepts.doc.html#25486">(&#167;2.4.7)</a>.
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<li>Numeric promotion, which brings the operands of a numeric operator to a common type so that an operation can be performed.
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<i>String conversion</i> only applies to operands of the binary <code>+</code> operator when one of the arguments is a <code>String</code>; it will not be covered further. <p>
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<h3>2.6.1	 Identity Conversions</h3>
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A conversion from a type to that same type is permitted for any type.
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<h3>2.6.2	 Widening Primitive Conversions</h3>
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The following conversions on primitive types are called the <i>widening primitive 
conversions</i>:
<p><ul><a name="19694"></a>
<li><code>byte</code> to <code>short</code>, <code>int</code>, <code>long</code>, <code>float</code>, or <code>double</code>
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<li><code>short</code> to <code>int</code>, <code>long</code>, <code>float</code>, or <code>double</code>
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<li><code>char</code> to <code>int</code>, <code>long</code>, <code>float</code>, or <code>double</code>
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<li><code>int</code> to <code>long</code>, <code>float</code>, or <code>double</code>
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<li><code>long</code> to <code>float</code> or <code>double</code>
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<li><code>float</code> to <code>double</code>
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Widening conversions do not lose information about the sign or order of magnitude of a numeric value. Conversions widening from an integral type to another integral type and from <code>float</code> to <code>double</code> do not lose any information at all; the numeric value is preserved exactly. Conversion of an <code>int</code> or a <code>long</code> value to <code>float</code>, or of a <code>long</code> value to <code>double</code>, may lose precision, that is, the result may lose some of the least significant bits of the value; the resulting floating-point value is a correctly rounded version of the integer value, using IEEE 754 round-to-nearest mode <a href="Concepts.doc.html#17889">(&#167;2.4.3)</a>.<p>
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According to this rule, a widening conversion of a signed integer value to an integral type simply sign-extends the two's-complement representation of the integer value to fill the wider format. A widening conversion of a value of type <code>char</code> to an integral type zero-extends the representation of the character value to fill the wider format.<p>
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Despite the fact that loss of precision may occur, widening conversions among primitive types never result in a runtime exception <a href="Concepts.doc.html#22727">(&#167;2.15)</a>.<p>
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<h3>2.6.3	 Narrowing Primitive Conversions</h3>
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The following conversions on primitive types are called <i>narrowing primitive conversions</i>:
<p><ul><a name="19767"></a>
<li><code>byte</code> to <code>char</code>
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<li><code>short</code> to <code>byte</code> or <code>char</code>
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<li><code>char</code> to <code>byte</code> or <code>short</code>
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<li><code>int</code> to <code>byte</code>, <code>short</code>, or <code>char</code>
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<li><code>long</code> to <code>byte</code>, <code>short</code>, <code>char</code>, or <code>int</code>
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<li><code>float</code> to <code>byte</code>, <code>short</code>, <code>char</code>, <code>int</code>, or <code>long</code>
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<li><code>double</code> to <code>byte</code>, <code>short</code>, <code>char</code>, <code>int</code>, <code>long</code>, or <code>float</code>
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Narrowing conversions may lose information about the sign or order of magnitude, or both, of a numeric value (for example, narrowing an <code>int</code> value <code>32763</code> to type <code>byte</code> produces the value <code>-5</code>). Narrowing conversions may also lose precision.<p>
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A narrowing conversion of a signed integer to an integral type simply discards all but the <i>n</i> lowest-order bits, where <i>n</i> is the number of bits used to represent the type. This may cause the resulting value to have a different sign than the input value.<p>
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A narrowing conversion of a character to an integral type likewise simply discards all but the <i>n</i> lowest bits, where <i>n</i> is the number of bits used to represent the type. This may cause the resulting value to be a negative number, even though characters represent 16-bit unsigned integer values.<p>
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In a narrowing conversion of a floating-point number to an integral type, if the floating-point number is <code></code>NaN, the result of the conversion is <code>0</code> of the appropriate type. If the floating-point number is too large to be represented by the integral type, or is positive infinity, the result is the largest representable value of the integral type. If the floating-point number is too small to be represented, or is negative infinity, the result is the smallest representable value of the integral type. Otherwise, the result is the floating-point number rounded towards zero to an integer value using IEEE 754 round-towards-zero mode <a href="Concepts.doc.html#17889">(&#167;2.4.3)</a><p>
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A narrowing conversion from <code>double</code> to <code>float</code> behaves in accordance with IEEE 754. The result is correctly rounded using IEEE 754 round-to-nearest mode <a href="Concepts.doc.html#17889">(&#167;2.4.3)</a>. A value too small to be represented as a <code>float</code> is converted to a positive or negative zero; a value too large to be represented as a <code>float</code> is converted to a positive or negative infinity. A <code>double</code> <code></code>NaN is always converted to a <code>float</code> <code></code>NaN.<p>
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Despite the fact that overflow, underflow, or loss of precision may occur, narrowing conversions among primitive types never result in a runtime exception.<p>
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<h3>2.6.4	 Widening Reference Conversions</h3>
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<em>Widening reference conversions</em> never require a special action at run time and 
therefore never throw an exception at run time. Because they do not affect the Java 
Virtual Machine, they will not be considered further.
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<h3>2.6.5	 Narrowing Reference Conversions</h3>
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The following permitted conversions are called the <i>narrowing reference conversions</i>:
<p><ul><a name="25687"></a>
<li>From any class type S<i></i> to any class type T<i></i>, provided that S<i></i> is a superclass of T<i></i>. (An important special case is that there is a narrowing conversion from the class type <code>Object</code> to any other class type.)
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<li>From any class type S<i></i> to any interface type K<i></i>, provided that S<i></i> is not <code>final</code> and does not implement K<i></i>. (An important special case is that there is a narrowing conversion from the class type <code>Object</code> to any interface type.)
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<li>From type <code>Object</code> to any array type.
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<li>From type <code>Object</code> to any interface type.
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<li>From any interface type J<i></i> to any class type T<i></i> that is not <code>final</code>.
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<li>From any interface type J<i></i> to any class type T<i></i> that is <code>final</code>, provided that T<i></i> implements J<i></i>.
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<li>From any interface type J<i></i> to any interface type K<i></i>, provided that J<i></i> is not a subinterface of K<i></i> and there is no method name m<i></i> such that J<i></i> and K<i></i> both declare a method named m<i></i> with the same signature but different return types.
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<li>From any array type SC<code>[]</code> to any array type TC<code>[]</code>, provided that SC<i></i> and TC<i></i> are reference types and there is a permitted narrowing conversion from SC<i></i> to TC<i></i>.
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Such conversions require a test at run time to find out whether the actual reference 
value is a legitimate value of the new type. If it is not, the Java Virtual Machine 
throws a <code>ClassCastException</code>.
<p><a name="19674"></a>
<h3>2.6.6	 Assignment Conversion</h3>
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<i>Assignment conversion</i> occurs when the value of an expression is assigned to a 
variable: the type of the expression must be converted to the type of the variable. 
Assignment contexts allow the use of an identity conversion <a href="Concepts.doc.html#19691">(&#167;2.6.1)</a>, a widening 
primitive conversion <a href="Concepts.doc.html#23435">(&#167;2.6.2)</a>, or a widening reference conversion <a href="Concepts.doc.html#25679">(&#167;2.6.4)</a>. In 
addition, a narrowing primitive conversion <a href="Concepts.doc.html#26142">(&#167;2.6.3)</a> may be used if all of the following conditions are satisfied:
<p><ul><a name="25751"></a>
<li>The expression is a constant expression of type <code>int</code>.
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<li>The type of the variable is <code>byte</code>, <code>short</code>, or <code>char</code>. 
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<li>The value of the expression is representable in the type of the variable.
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If the type of the expression can be converted to the type of a variable by assignment conversion, we say the expression (or its value) is <i>assignable</i> to the variable or, equivalently, that the type of the expression is <i>assignment compatible</i> with the type of the variable.<p>
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An assignment conversion never causes an exception. A value of primitive type must not be assigned to a variable of reference type. A value of reference type must not be assigned to a variable of primitive type. A value of type <code>boolean</code> can be assigned only to a variable to type <code>boolean</code>. A value of the null type may be assigned to any reference type.<p>
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Assignment of a value of compile-time reference type S (source) to a variable of compile-time reference type T (target) is permitted:<p>
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<li>If S is a class type:
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<li>If T is a class type, then S must be the same class as T, or S must be a subclass of T.
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<li>If T is an interface type, then S must implement interface T.
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<li>If S is an interface type:
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