Java 父类的公共方法和字段
父类的公共方法和字段
实例源码：
源代码：
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/*from N o w J a v a . c o m*/2
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public class AlphaTwo extends Alpha {4
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public static void main(String[] args) {6
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Alpha a = new Alpha();8
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//a.privateMethod(); //illegal10
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//a.packageMethod(); //illegal12
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//a.protectedMethod(); //illegal14
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a.publicMethod(); //legal16
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//System.out.format("privateVariable: %2d%n",19
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// a.privateVariable); //illegal21
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//System.out.format("packageVariable: %2d%n",23
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// a.packageVariable); //illegal25
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//System.out.format("protectedVariable: %2d%n",27
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// a.protectedVariable); //illegal29
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System.out.format("publicVariable: %2d%n", a.publicVariable); //legal31
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AlphaTwo a2 = new AlphaTwo();34
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a2.protectedMethod(); //legal36
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System.out.format("protectedVariable: %2d%n", a2.protectedVariable); //legal38
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}40
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}42
/**43
时 代 J a v a 公 众 号 - nowjava.com 提供 44
**/45
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class Alpha {48
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//member variables51
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private int privateVariable = 1;53
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int packageVariable = 2; //default access55
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protected int protectedVariable = 3;57
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public int publicVariable = 4;59
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//methods62
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private void privateMethod() {64
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System.out.format("privateMethod called%n");66
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}68
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void packageMethod() { //default access71
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System.out.format("packageMethod called%n");73
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}75
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protected void protectedMethod() {78
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System.out.format("protectedMethod called%n");80
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}82
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public void publicMethod() {85
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System.out.format("publicMethod called%n");87
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}89
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public static void main(String[] args) {92
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Alpha a = new Alpha();94
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a.privateMethod(); //legal96
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a.packageMethod(); //legal98
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a.protectedMethod(); //legal100
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a.publicMethod(); //legal102
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System.out.format("privateVariable: %2d%n", a.privateVariable); //legal105
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System.out.format("packageVariable: %2d%n", a.packageVariable); //legal107
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System.out.format("protectedVariable: %2d%n", a.protectedVariable); //legal109
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System.out.format("publicVariable: %2d%n", a.publicVariable); //legal111
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}113
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}115
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/*117
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* Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.119
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*121
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* Redistribution and use in source and binary forms, with or without123
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* modification, are permitted provided that the following conditions125
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* are met:127
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*129
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* - Redistributions of source code must retain the above copyright131
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* notice, this list of conditions and the following disclaimer.133
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*135
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* - Redistributions in binary form must reproduce the above copyright137
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* notice, this list of conditions and the following disclaimer in the139
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* documentation and/or other materials provided with the distribution.141
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*143
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* - Neither the name of Oracle or the names of its145
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* contributors may be used to endorse or promote products derived147
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* from this software without specific prior written permission.149
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*151
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS153
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* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,155
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR157
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