text: (window.webpackJsonp=window.webpackJsonp||[]).push([[199],{548:function(t,s,a){"use strict";a.r(s);var n=a(42),e=Object(n.a)({},(function(){var t=this,s=t.$createElement,a=t._self._c||s;return a("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[a("h1",{attrs:{id:"java-方法"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#java-方法"}},[t._v("#")]),t._v(" Java 方法")]),t._v(" "),a("h2",{attrs:{id:"概述"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#概述"}},[t._v("#")]),t._v(" 概述")]),t._v(" "),a("p",[t._v("在前面几个章节中我们经常使用到System.out.println()，那么它是什么呢？")]),t._v(" "),a("p",[t._v("println()是一个方法(Method)，而System是系统类(Class)，out是标准输出对象(Object)。这句话的用法是调用系统类System中的标准输出对象out中的方法println()。")]),t._v(" "),a("h3",{attrs:{id:"那么什么是方法呢？"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#那么什么是方法呢？"}},[t._v("#")]),t._v(" 那么什么是方法呢？")]),t._v(" "),a("p",[t._v("Java方法是语句的集合，它们在一起执行一个功能。")]),t._v(" "),a("ul",[a("li",[t._v("方法是解决一类问题的步骤的有序组合")]),t._v(" "),a("li",[t._v("方法包含于类或对象中")]),t._v(" "),a("li",[t._v("方法在程序中被创建，在其他地方被引用")])]),t._v(" "),a("h2",{attrs:{id:"方法的定义"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#方法的定义"}},[t._v("#")]),t._v(" 方法的定义")]),t._v(" "),a("p",[t._v("一般情况下，定义一个方法包含以下语法：")]),t._v(" "),a("div",{staticClass:"language- extra-class"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("修饰符 返回值类型 方法名 (参数类型 参数名){\n    ...\n    方法体\n    ...\n    return 返回值;\n}\n")])])]),a("p",[t._v("方法包含一个方法头和一个方法体。下面是一个方法的所有部分：")]),t._v(" "),a("ul",[a("li",[t._v("修饰符：修饰符，这是可选的，告诉编译器如何调用该方法。定义了该方法的访问类型。")]),t._v(" "),a("li",[t._v("返回值类型 ：方法可能会返回值。returnValueType是方法返回值的数据类型。有些方法执行所需的操作，但没有返回值。在这种情况下，returnValueType是关键字void。")]),t._v(" "),a("li",[t._v("方法名：是方法的实际名称。方法名和参数表共同构成方法签名。")]),t._v(" "),a("li",[t._v("参数类型：参数像是一个占位符。当方法被调用时，传递值给参数。这个值被称为实参或变量。参数列表是指方法的参数类型、顺序和参数的个数。参数是可选的，方法可以不包含任何参数。")]),t._v(" "),a("li",[t._v("方法体：方法体包含具体的语句，定义该方法的功能。")])]),t._v(" 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"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n         "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("out"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("println")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v("'D'")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("else")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n         "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token 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"),a("h2",{attrs:{id:"通过值传递参数"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#通过值传递参数"}},[t._v("#")]),t._v(" 通过值传递参数")]),t._v(" "),a("p",[t._v("调用一个方法时候需要提供参数，你必须按照参数列表指定的顺序提供。")]),t._v(" "),a("p",[t._v("例如，下面的方法连续n次打印一个消息：")]),t._v(" "),a("div",{staticClass:"language-java extra-class"},[a("pre",{pre:!0,attrs:{class:"language-java"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("static")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("void")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("nPrintln")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("String")]),t._v(" message"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" n"),a("span",{pre:!0,attrs:{class:"token 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string"}},[t._v('" and num2 is "')]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" num2"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n\n      "),a("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 调用swap方法")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("swap")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("num1"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" num2"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("out"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token 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"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("void")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("swap")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" n1"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" n2"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("out"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("println")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"\\tInside the swap method"')]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("out"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("println")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"\\t\\tBefore swapping n1 is "')]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" n1\n                           "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('" n2 is "')]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" n2"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 交换 n1 与 n2的值")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" temp "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" n1"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n      n1 "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" n2"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n      n2 "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" temp"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n\n      "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("out"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("println")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"\\t\\tAfter swapping n1 is "')]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" n1\n                           "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('" n2 is "')]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" n2"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n")])])]),a("p",[t._v("以上实例编译运行结果如下：")]),t._v(" "),a("div",{staticClass:"language- extra-class"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("Before swap method, num1 is 1 and num2 is 2\n        Inside the swap method\n                Before swapping n1 is 1 n2 is 2\n                After swapping n1 is 2 n2 is 1\nAfter swap method, num1 is 1 and num2 is 2\n")])])]),a("p",[t._v("传递两个参数调用swap方法。有趣的是，方法被调用后，实参的值并没有改变。")]),t._v(" "),a("h2",{attrs:{id:"方法的重载"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#方法的重载"}},[t._v("#")]),t._v(" 方法的重载")]),t._v(" "),a("p",[t._v("上面使用的max方法仅仅适用于int型数据。但如果你想得到两个浮点类型数据的最大值呢？")]),t._v(" "),a("p",[t._v("解决方法是创建另一个有相同名字但参数不同的方法，如下面代码所示：")]),t._v(" "),a("div",{staticClass:"language-java extra-class"},[a("pre",{pre:!0,attrs:{class:"language-java"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("static")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("double")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("max")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("double")]),t._v(" num1"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(",")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("double")]),t._v(" num2"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("if")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),t._v("num1 "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v(">")]),t._v(" num2"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v("\n    "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("return")]),t._v(" num1"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n  "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("else")]),t._v("\n    "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("return")]),t._v(" num2"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n")])])]),a("p",[t._v("如果你调用max方法时传递的是int型参数，则 int型参数的max方法就会被调用；")]),t._v(" "),a("p",[t._v("如果传递的是double型参数，则double类型的max方法体会被调用，这叫做方法重载；")]),t._v(" "),a("p",[t._v("就是说一个类的两个方法拥有相同的名字，但是有不同的参数列表。")]),t._v(" "),a("p",[t._v("Java编译器根据方法签名判断哪个方法应该被调用。")]),t._v(" "),a("p",[t._v("方法重载可以让程序更清晰易读。执行密切相关任务的方法应该使用相同的名字。")]),t._v(" "),a("p",[t._v("重载的方法必须拥有不同的参数列表。你不能仅仅依据修饰符或者返回类型的不同来重载方法。")]),t._v(" "),a("h2",{attrs:{id:"变量作用域"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#变量作用域"}},[t._v("#")]),t._v(" 变量作用域")]),t._v(" "),a("p",[t._v("变量的范围是程序中该变量可以被引用的部分。")]),t._v(" "),a("p",[t._v("方法内定义的变量被称为局部变量。")]),t._v(" "),a("p",[t._v("局部变量的作用范围从声明开始，直到包含它的块结束。")]),t._v(" "),a("p",[t._v("局部变量必须声明才可以使用。")]),t._v(" "),a("p",[t._v("方法的参数范围涵盖整个方法。参数实际上是一个局部变量。")]),t._v(" "),a("p",[t._v("for循环的初始化部分声明的变量，其作用范围在整个循环。")]),t._v(" "),a("p",[t._v("但循环体内声明的变量其适用范围是从它声明到循环体结束。它包含如下所示的变量声明：\n")]),a("div",{attrs:{align:"center"}},[a("img",{attrs:{src:"http://ww1.sinaimg.cn/large/007Rnr4nly1g8w8id715bj30by060glk.jpg"}})]),t._v("\n你可以在一个方法里，不同的非嵌套块中多次声明一个具有相同的名称局部变量，但你不能在嵌套块内两次声明局部变量。"),a("p"),t._v(" "),a("h2",{attrs:{id:"命令行参数的使用"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#命令行参数的使用"}},[t._v("#")]),t._v(" 命令行参数的使用")]),t._v(" "),a("p",[t._v("有时候你希望运行一个程序时候再传递给它消息。这要靠传递命令行参数给main()函数实现。")]),t._v(" "),a("p",[t._v("命令行参数是在执行程序时候紧跟在程序名字后面的信息。")]),t._v(" "),a("p",[t._v("实例\n下面的程序打印所有的命令行参数：")]),t._v(" "),a("div",{staticClass:"language-java extra-class"},[a("pre",{pre:!0,attrs:{class:"language-java"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("class")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("CommandLine")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n\n   "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("static")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("void")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("main")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("String")]),t._v(" args"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v(" \n      "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("for")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" i"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),a("span",{pre:!0,attrs:{class:"token number"}},[t._v("0")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" i"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("<")]),t._v("args"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("length"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v(" i"),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("++")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("          "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("out"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("println")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"args["')]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" i "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token string"}},[t._v('"]: "')]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("+")]),t._v("                                            args"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),t._v("i"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("       "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("    "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n")])])]),a("p",[t._v("如下所示，运行这个程序：")]),t._v(" "),a("div",{staticClass:"language- extra-class"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("java CommandLine this is a command line 200 -100\n")])])]),a("p",[t._v("运行结果如下：")]),t._v(" "),a("div",{staticClass:"language- extra-class"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("args[0]: this\nargs[1]: is\nargs[2]: a\nargs[3]: command\nargs[4]: line\nargs[5]: 200\nargs[6]: -100\n")])])]),a("h2",{attrs:{id:"构造方法"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#构造方法"}},[t._v("#")]),t._v(" 构造方法")]),t._v(" "),a("p",[t._v("当一个对象被创建时候，构造方法用来初始化该对象。构造方法和它所在类的名字相同，但构造方法没有返回值。")]),t._v(" "),a("p",[t._v("通常会使用构造方法给一个类的实例变量赋初值，或者执行其它必要的步骤来创建一个完整的对象。")]),t._v(" "),a("p",[t._v("不管你与否自定义构造方法，所有的类都有构造方法，因为Java自动提供了一个默认构造方法，它把所有成员初始化为0。")]),t._v(" "),a("p",[t._v("一旦你定义了自己的构造方法，默认构造方法就会失效。")]),t._v(" "),a("p",[t._v("实例")]),t._v(" "),a("p",[t._v("下面是一个使用构造方法的例子：")]),t._v(" "),a("div",{staticClass:"language-java extra-class"},[a("pre",{pre:!0,attrs:{class:"language-java"}},[a("code",[a("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 一个简单的构造函数")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("class")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("MyClass")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" x"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n   \n   "),a("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 以下是构造函数")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("MyClass")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n      x "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token number"}},[t._v("10")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("}")]),t._v("\n")])])]),a("p",[t._v("你可以像下面这样调用构造方法来初始化一个对象：")]),t._v(" "),a("div",{staticClass:"language-java extra-class"},[a("pre",{pre:!0,attrs:{class:"language-java"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("class")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("ConsDemo")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n\n   "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("static")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("void")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("main")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("String")]),t._v(" args"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("MyClass")]),t._v(" t1 "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("new")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("MyClass")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("MyClass")]),t._v(" t2 "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("new")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("MyClass")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("out"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),a("span",{pre:!0,attrs:{class:"token function"}},[t._v("println")]),a("span",{pre:!0,attrs:{class:"token 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一个简单的构造函数")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("class")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("MyClass")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" x"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n   \n   "),a("span",{pre:!0,attrs:{class:"token comment"}},[t._v("// 以下是构造函数")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("MyClass")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("(")]),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("int")]),t._v(" i "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(")")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n      x "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" i"),a("span",{pre:!0,attrs:{class:"token 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"),a("p",[t._v("方法的可变参数的声明如下所示：")]),t._v(" "),a("div",{staticClass:"language- extra-class"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("typeName... parameterName\n")])])]),a("p",[t._v("在方法声明中，在指定参数类型后加一个省略号(...) 。")]),t._v(" "),a("p",[t._v("一个方法中只能指定一个可变参数，它必须是方法的最后一个参数。任何普通的参数必须在它之前声明。")]),t._v(" "),a("p",[t._v("实例")]),t._v(" "),a("div",{staticClass:"language-java extra-class"},[a("pre",{pre:!0,attrs:{class:"language-java"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("class")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("VarargsDemo")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n\n   "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("static")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("void")]),t._v(" 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"),a("div",{staticClass:"language- extra-class"},[a("pre",{pre:!0,attrs:{class:"language-text"}},[a("code",[t._v("C:\\1>java FinalizationDemo  \nCake Object 1is created  \nCake Object 2is created  \nCake Object 3is created  \nCake Object 3is disposed  \nCake Object 2is disposed\n")])])])])}),[],!1,null,null,null);s.default=e.exports}}]);