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wangScore是一个int类型的数据并且进行了初始化赋值80.而zhangScore仅仅只是定32313133353236313431303231363533e4b893e5b19e31333330343938义了一个int类型的变量,并没有初始化赋值.因此zhangScore=wangScore这句相当于是对zhangScore进行初始化赋值.wangScore已经是初始化过的所以可以把它的值赋给zhangScore.但是zhangScore并没有初始化赋值,因此不能去赋值给wangScore.这就是为什么它俩不能颠倒.如果你一开始就对zhangScore进行初始化赋值,那么它俩颠倒就没事了,因为那样就是两个都初始化过的值再进行赋值了.

"张萌的成绩是:"这是一个String类型的字符串,会按照原样输出.后面的int变量在输出的时候也是转化成String类型输出,所以你要打印的是两个字符串,java默认的就是使用+作为拼接的连接符号.其实+就是调用了一个方法.

附赠源码:

/**

* Prints an integer. The string produced by {@link

* java.lang.String#valueOf(int)} is translated into bytes

* according to the platform's default character encoding, and these bytes

* are written in exactly the manner of the

* {@link #write(int)} method.

*

* @param i The int to be printed

* @see java.lang.Integer#toString(int)

*/

public void print(int i) {

write(String.valueOf(i));

}

以上是打印int类型的方法,以下是字符串拼接的方法

/**

* The String class represents character strings. All

* string literals in Java programs, such as "abc", are

* implemented as instances of this class.

*

* Strings are constant; their values cannot be changed after they

* are created. String buffers support mutable strings.

* Because String objects are immutable they can be shared. For example:

*

* String str = "abc";

*

* is equivalent to:

*

* char data[] = {'a', 'b', 'c'};

* String str = new String(data);

*

* Here are some more examples of how strings can be used:

*

* System.out.println("abc");

* String cde = "cde";

* System.out.println("abc" + cde);

* String c = "abc".substring(2,3);

* String d = cde.substring(1, 2);

*

*

* The class String includes methods for examining

* individual characters of the sequence, for comparing strings, for

* searching strings, for extracting substrings, and for creating a

* copy of a string with all characters translated to uppercase or to

* lowercase. Case mapping is based on the Unicode Standard version

* specified by the {@link java.lang.Character Character} class.

*

* The Java language provides special support for the string

* concatenation operator ( + ), and for conversion of

* other objects to strings. String concatenation is implemented

* through the StringBuilder(or StringBuffer)

* class and its append method.

* String conversions are implemented through the method

* toString, defined by Object and

* inherited by all classes in Java. For additional information on

* string concatenation and conversion, see Gosling, Joy, and Steele,

* The Java Language Specification.

*

*

Unless otherwise noted, passing a null argument to a constructor

* or method in this class will cause a {@link NullPointerException} to be

* thrown.

*

*

A String represents a string in the UTF-16 format

* in which supplementary characters are represented by surrogate

* pairs (see the section Unicode

* Character Representations in the Character class for

* more information).

* Index values refer to char code units, so a supplementary

* character uses two positions in a String.

*

The String class provides methods for dealing with

* Unicode code points (i.e., characters), in addition to those for

* dealing with Unicode code units (i.e., char values).

*

* @author Lee Boynton

* @author Arthur van Hoff

* @version 1.204, 06/09/06

* @see java.lang.Object#toString()

* @see java.lang.StringBuffer

* @see java.lang.StringBuilder

* @see java.nio.charset.Charset

* @since JDK1.0

*/

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谢谢 能做个朋友吗？ 呵呵 高手啊

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