3-Third commit for articles:
* to core-java-lang: * https://www.baeldung.com/java-lang-system * https://www.baeldung.com/java-type-erasure * https://www.baeldung.com/java-assert * https://www.baeldung.com/java-pass-by-value-or-pass-by-reference * https://www.baeldung.com/java-variable-method-hiding * https://www.baeldung.com/java-access-modifiers * https://www.baeldung.com/java-super * https://www.baeldung.com/java-this * https://www.baeldung.com/java-immutable-object * https://www.baeldung.com/java-classnotfoundexception-and-noclassdeffounderror * https://www.baeldung.com/infinite-loops-java (changes for this were included in commit 1, with other loop-related examples)
This commit is contained in:
geroza
@@ -1,9 +0,0 @@
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package com.baeldung.accessmodifiers;
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public class Public {
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public Public() {
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SuperPublic.publicMethod(); // Available everywhere.
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SuperPublic.protectedMethod(); // Available in the same package or subclass.
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SuperPublic.defaultMethod(); // Available in the same package.
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}
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}
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@@ -1,9 +0,0 @@
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package com.baeldung.accessmodifiers;
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public class SubClass extends SuperPublic {
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public SubClass() {
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SuperPublic.publicMethod(); // Available everywhere.
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SuperPublic.protectedMethod(); // Available in the same package or subclass.
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SuperPublic.defaultMethod(); // Available in the same package.
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}
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}
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@@ -1,39 +0,0 @@
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package com.baeldung.accessmodifiers;
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//Only public or default access modifiers are permitted
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public class SuperPublic {
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// Always available from anywhere
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static public void publicMethod() {
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System.out.println(SuperPublic.class.getName() + " publicMethod()");
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}
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// Available within the same package
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static void defaultMethod() {
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System.out.println(SuperPublic.class.getName() + " defaultMethod()");
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}
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// Available within the same package and subclasses
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static protected void protectedMethod() {
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System.out.println(SuperPublic.class.getName() + " protectedMethod()");
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}
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// Available within the same class only
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static private void privateMethod() {
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System.out.println(SuperPublic.class.getName() + " privateMethod()");
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}
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// Method in the same class = has access to all members within the same class
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private void anotherPrivateMethod() {
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privateMethod();
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defaultMethod();
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protectedMethod();
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publicMethod(); // Available in the same class only.
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}
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}
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// Only public or default access modifiers are permitted
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class SuperDefault {
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public void publicMethod() {
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System.out.println(this.getClass().getName() + " publicMethod()");
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}
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}
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@@ -1,9 +0,0 @@
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package com.baeldung.accessmodifiers.another;
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import com.baeldung.accessmodifiers.SuperPublic;
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public class AnotherPublic {
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public AnotherPublic() {
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SuperPublic.publicMethod(); // Available everywhere.
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}
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}
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@@ -1,10 +0,0 @@
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package com.baeldung.accessmodifiers.another;
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import com.baeldung.accessmodifiers.SuperPublic;
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public class AnotherSubClass extends SuperPublic {
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public AnotherSubClass() {
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SuperPublic.publicMethod(); // Available everywhere.
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SuperPublic.protectedMethod(); // Available in subclass. Let's note different package.
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}
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}
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@@ -1,9 +0,0 @@
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package com.baeldung.accessmodifiers.another;
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import com.baeldung.accessmodifiers.SuperPublic;
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public class AnotherSuperPublic {
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public AnotherSuperPublic() {
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SuperPublic.publicMethod(); // Available everywhere. Let's note different package.
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}
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}
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@@ -1,26 +0,0 @@
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package com.baeldung.assertion;
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/**
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* Simple demonstration of using Java assert keyword.
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*/
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public class Assertion {
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public static void main(String[] args) {
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Assertion assertion = new Assertion();
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assertion.setup();
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}
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public void setup() {
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Object conn = getConnection();
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assert conn != null : "Connection is null";
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|
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// continue with other setup ...
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}
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// Simulate failure to get a connection; using Object
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// to avoid dependencies on JDBC or some other heavy
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// 3rd party library
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public Object getConnection() {
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return null;
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}
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}
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@@ -1,18 +0,0 @@
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package com.baeldung.immutableobjects;
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public final class Currency {
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private final String value;
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private Currency(String currencyValue) {
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value = currencyValue;
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}
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public String getValue() {
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return value;
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}
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public static Currency of(String value) {
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return new Currency(value);
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}
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}
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@@ -1,20 +0,0 @@
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package com.baeldung.immutableobjects;
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// 4. Immutability in Java
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public final class Money {
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private final double amount;
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private final Currency currency;
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public Money(double amount, Currency currency) {
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this.amount = amount;
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this.currency = currency;
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}
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public Currency getCurrency() {
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return currency;
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}
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public double getAmount() {
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return amount;
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}
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}
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@@ -1,16 +0,0 @@
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package com.baeldung.keyword;
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import com.baeldung.keyword.superkeyword.SuperSub;
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import com.baeldung.keyword.thiskeyword.KeywordUnitTest;
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/**
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* Created by Gebruiker on 5/14/2018.
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*/
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public class KeywordDemo {
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public static void main(String[] args) {
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KeywordUnitTest keyword = new KeywordUnitTest();
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SuperSub child = new SuperSub("message from the child class");
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}
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}
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@@ -1,20 +0,0 @@
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package com.baeldung.keyword.superkeyword;
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/**
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* Created by Gebruiker on 5/14/2018.
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*/
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public class SuperBase {
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String message = "super class";
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public SuperBase() {
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}
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public SuperBase(String message) {
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this.message = message;
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}
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public void printMessage() {
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System.out.println(message);
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}
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}
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@@ -1,26 +0,0 @@
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package com.baeldung.keyword.superkeyword;
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/**
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* Created by Gebruiker on 5/15/2018.
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*/
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public class SuperSub extends SuperBase {
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String message = "child class";
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public SuperSub(String message) {
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super(message);
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}
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public SuperSub() {
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super.printMessage();
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printMessage();
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}
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public void getParentMessage() {
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System.out.println(super.message);
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}
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public void printMessage() {
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System.out.println(message);
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}
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}
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@@ -1,49 +0,0 @@
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package com.baeldung.keyword.thiskeyword;
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public class KeywordUnitTest {
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private String name;
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private int age;
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public KeywordUnitTest() {
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this("John", 27);
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this.printMessage();
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printInstance(this);
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}
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public KeywordUnitTest(String name, int age) {
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this.name = name;
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this.age = age;
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}
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public void printMessage() {
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System.out.println("invoked by this");
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}
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public void printInstance(KeywordUnitTest thisKeyword) {
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System.out.println(thisKeyword);
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}
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public KeywordUnitTest getCurrentInstance() {
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return this;
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}
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class ThisInnerClass {
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boolean isInnerClass = true;
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public ThisInnerClass() {
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KeywordUnitTest thisKeyword = KeywordUnitTest.this;
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String outerString = KeywordUnitTest.this.name;
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System.out.println(this.isInnerClass);
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}
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}
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@Override
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public String toString() {
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return "KeywordTest{" +
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"name='" + name + '\'' +
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", age=" + age +
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'}';
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}
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}
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@@ -1,5 +0,0 @@
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package com.baeldung.noclassdeffounderror;
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public class ClassWithInitErrors {
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static int data = 1 / 0;
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}
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-14
@@ -1,14 +0,0 @@
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package com.baeldung.noclassdeffounderror;
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public class NoClassDefFoundErrorExample {
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public ClassWithInitErrors getClassWithInitErrors() {
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ClassWithInitErrors test;
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try {
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test = new ClassWithInitErrors();
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} catch (Throwable t) {
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System.out.println(t);
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}
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test = new ClassWithInitErrors();
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return test;
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}
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}
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@@ -1,27 +0,0 @@
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package com.baeldung.parameterpassing;
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public class NonPrimitives {
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public static void main(String[] args) {
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FooClass a = new FooClass(1);
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FooClass b = new FooClass(1);
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System.out.printf("Before Modification: a = %d and b = %d ", a.num, b.num);
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modify(a, b);
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System.out.printf("\nAfter Modification: a = %d and b = %d ", a.num, b.num);
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}
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public static void modify(FooClass a1, FooClass b1) {
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a1.num++;
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b1 = new FooClass(1);
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b1.num++;
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}
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}
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class FooClass {
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public int num;
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public FooClass(int num) {
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this.num = num;
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}
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}
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@@ -1,17 +0,0 @@
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package com.baeldung.parameterpassing;
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public class Primitives {
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public static void main(String[] args) {
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int x = 1;
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int y = 2;
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|
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System.out.printf("Before Modification: x = %d and y = %d ", x, y);
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modify(x, y);
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System.out.printf("\nAfter Modification: x = %d and y = %d ", x, y);
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}
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public static void modify(int x1, int y1) {
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x1 = 5;
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y1 = 10;
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||||
}
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}
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@@ -1,9 +0,0 @@
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package com.baeldung.scope.method;
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|
||||
|
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public class BaseMethodClass {
|
||||
|
||||
public static void printMessage() {
|
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System.out.println("base static method");
|
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}
|
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}
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@@ -1,9 +0,0 @@
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package com.baeldung.scope.method;
|
||||
|
||||
|
||||
public class ChildMethodClass extends BaseMethodClass {
|
||||
|
||||
public static void printMessage() {
|
||||
System.out.println("child static method");
|
||||
}
|
||||
}
|
||||
@@ -1,8 +0,0 @@
|
||||
package com.baeldung.scope.method;
|
||||
|
||||
public class MethodHidingDemo {
|
||||
|
||||
public static void main(String[] args) {
|
||||
ChildMethodClass.printMessage();
|
||||
}
|
||||
}
|
||||
@@ -1,13 +0,0 @@
|
||||
package com.baeldung.scope.variable;
|
||||
|
||||
/**
|
||||
* Created by Gebruiker on 5/7/2018.
|
||||
*/
|
||||
public class ChildVariable extends ParentVariable {
|
||||
|
||||
String instanceVariable = "child variable";
|
||||
|
||||
public void printInstanceVariable() {
|
||||
System.out.println(instanceVariable);
|
||||
}
|
||||
}
|
||||
@@ -1,23 +0,0 @@
|
||||
package com.baeldung.scope.variable;
|
||||
|
||||
/**
|
||||
* Created by Gebruiker on 5/6/2018.
|
||||
*/
|
||||
public class HideVariable {
|
||||
|
||||
private String message = "this is instance variable";
|
||||
|
||||
HideVariable() {
|
||||
String message = "constructor local variable";
|
||||
System.out.println(message);
|
||||
}
|
||||
|
||||
public void printLocalVariable() {
|
||||
String message = "method local variable";
|
||||
System.out.println(message);
|
||||
}
|
||||
|
||||
public void printInstanceVariable() {
|
||||
System.out.println(this.message);
|
||||
}
|
||||
}
|
||||
@@ -1,13 +0,0 @@
|
||||
package com.baeldung.scope.variable;
|
||||
|
||||
/**
|
||||
* Created by Gebruiker on 5/7/2018.
|
||||
*/
|
||||
public class ParentVariable {
|
||||
|
||||
String instanceVariable = "parent variable";
|
||||
|
||||
public void printInstanceVariable() {
|
||||
System.out.println(instanceVariable);
|
||||
}
|
||||
}
|
||||
@@ -1,18 +0,0 @@
|
||||
package com.baeldung.scope.variable;
|
||||
|
||||
/**
|
||||
* Created by Gebruiker on 5/6/2018.
|
||||
*/
|
||||
public class VariableHidingDemo {
|
||||
public static void main(String[] args) {
|
||||
HideVariable variable = new HideVariable();
|
||||
variable.printLocalVariable();
|
||||
variable.printInstanceVariable();
|
||||
|
||||
ParentVariable parentVariable = new ParentVariable();
|
||||
ParentVariable childVariable = new ChildVariable();
|
||||
|
||||
parentVariable.printInstanceVariable();
|
||||
childVariable.printInstanceVariable();
|
||||
}
|
||||
}
|
||||
@@ -1,17 +0,0 @@
|
||||
package com.baeldung.system;
|
||||
|
||||
import java.awt.event.WindowEvent;
|
||||
|
||||
/**
|
||||
* Note: This class is not meant for unit-testing since it uses system
|
||||
* features at low level and that it uses 'System' gc() which suggests
|
||||
* JVM for garbage collection. But the usage below demonstrates how the
|
||||
* method can be used.
|
||||
*/
|
||||
public class ChatWindow {
|
||||
public void windowStateChanged(WindowEvent event) {
|
||||
if (event.getNewState() == WindowEvent.WINDOW_DEACTIVATED ) {
|
||||
System.gc(); // if it ends up running, great!
|
||||
}
|
||||
}
|
||||
}
|
||||
@@ -1,16 +0,0 @@
|
||||
package com.baeldung.system;
|
||||
|
||||
import java.util.Date;
|
||||
|
||||
public class DateTimeService {
|
||||
|
||||
// One hour from now
|
||||
public long nowPlusOneHour() {
|
||||
return System.currentTimeMillis() + 3600 * 1000L;
|
||||
}
|
||||
|
||||
// Human-readable format
|
||||
public String nowPrettyPrinted() {
|
||||
return new Date(System.currentTimeMillis()).toString();
|
||||
}
|
||||
}
|
||||
@@ -1,7 +0,0 @@
|
||||
package com.baeldung.system;
|
||||
|
||||
public class EnvironmentVariables {
|
||||
public String getPath() {
|
||||
return System.getenv("PATH");
|
||||
}
|
||||
}
|
||||
@@ -1,18 +0,0 @@
|
||||
package com.baeldung.system;
|
||||
|
||||
/**
|
||||
* Note: This class is not meant for unit-testing since it uses system
|
||||
* features at low level and that it uses 'System' standard error stream
|
||||
* methods to show output on screen. Also unit-tests in CI environments
|
||||
* don't have console output for user to see messages. But the usage below
|
||||
* demonstrates how the methods can be used.
|
||||
*/
|
||||
public class SystemErrDemo {
|
||||
public static void main(String[] args) {
|
||||
// Print without 'hitting' return
|
||||
System.err.print("some inline error message");
|
||||
|
||||
// Print and then 'hit' return
|
||||
System.err.println("an error message having new line at the end");
|
||||
}
|
||||
}
|
||||
@@ -1,24 +0,0 @@
|
||||
package com.baeldung.system;
|
||||
|
||||
/**
|
||||
* Note: This class is not meant for unit-testing since it uses system
|
||||
* features at low level and that it uses 'System' exit() which will
|
||||
* exit the JVM. Also unit-tests in CI environments are not meant to
|
||||
* exit unit tests like that. But the usage below demonstrates how the
|
||||
* method can be used.
|
||||
*/
|
||||
public class SystemExitDemo {
|
||||
public static void main(String[] args) {
|
||||
boolean error = false;
|
||||
|
||||
// do something and set error value
|
||||
|
||||
if (error) {
|
||||
System.exit(1); // error case exit
|
||||
} else {
|
||||
System.exit(0); // normal case exit
|
||||
}
|
||||
|
||||
// Will not do anything after exit()
|
||||
}
|
||||
}
|
||||
@@ -1,25 +0,0 @@
|
||||
package com.baeldung.system;
|
||||
|
||||
import java.io.FileNotFoundException;
|
||||
import java.io.PrintStream;
|
||||
|
||||
/**
|
||||
* Note: This class is not meant for unit-testing since it uses system
|
||||
* features at low level and that it uses 'System' standard output stream
|
||||
* methods to show output on screen. Also unit-tests in CI environments
|
||||
* don't have console output for user to see messages. But the usage below
|
||||
* demonstrates how the methods can be used.
|
||||
*/
|
||||
public class SystemOutDemo {
|
||||
|
||||
public static void main(String[] args) throws FileNotFoundException {
|
||||
// Print without 'hitting' return
|
||||
System.out.print("some inline message");
|
||||
|
||||
// Print and then 'hit' return
|
||||
System.out.println("a message having new line at the end");
|
||||
|
||||
// Changes output stream to send messages to file.
|
||||
System.setOut(new PrintStream("file.txt"));
|
||||
}
|
||||
}
|
||||
@@ -1,35 +0,0 @@
|
||||
package com.baeldung.system;
|
||||
|
||||
import java.io.BufferedReader;
|
||||
import java.io.Console;
|
||||
import java.io.IOException;
|
||||
import java.io.InputStreamReader;
|
||||
|
||||
/**
|
||||
* Note: This class is not meant for unit-testing since it uses system
|
||||
* features at low level and that it uses 'System' standard input stream
|
||||
* methods to read text from user. Also unit-tests in CI environments
|
||||
* don't have console input for user to type in text. But the usage below
|
||||
* demonstrates how the methods can be used.
|
||||
*/
|
||||
public class UserCredentials {
|
||||
|
||||
public String readUsername(int length) throws IOException {
|
||||
byte[] name = new byte[length];
|
||||
System.in.read(name, 0, length); // by default, from the console
|
||||
return new String(name);
|
||||
}
|
||||
|
||||
public String readUsername() throws IOException {
|
||||
BufferedReader reader =
|
||||
new BufferedReader(new InputStreamReader(System.in));
|
||||
return reader.readLine();
|
||||
}
|
||||
|
||||
public String readUsernameWithPrompt() {
|
||||
Console console = System.console();
|
||||
|
||||
return console == null ? null : // Console not available
|
||||
console.readLine("%s", "Enter your name: ");
|
||||
}
|
||||
}
|
||||
@@ -1,16 +0,0 @@
|
||||
package com.baeldung.typeerasure;
|
||||
|
||||
public class ArrayContentPrintUtil {
|
||||
|
||||
public static <E> void printArray(E[] array) {
|
||||
for (E element : array) {
|
||||
System.out.printf("%s ", element);
|
||||
}
|
||||
}
|
||||
|
||||
public static <E extends Comparable<E>> void printArray(E[] array) {
|
||||
for (E element : array) {
|
||||
System.out.printf("%s ", element);
|
||||
}
|
||||
}
|
||||
}
|
||||
@@ -1,37 +0,0 @@
|
||||
package com.baeldung.typeerasure;
|
||||
|
||||
import java.util.Arrays;
|
||||
|
||||
public class BoundStack<E extends Comparable<E>> {
|
||||
|
||||
private E[] stackContent;
|
||||
private int total;
|
||||
|
||||
public BoundStack(int capacity) {
|
||||
this.stackContent = (E[]) new Object[capacity];
|
||||
}
|
||||
|
||||
public void push(E data) {
|
||||
if (total == stackContent.length) {
|
||||
resize(2 * stackContent.length);
|
||||
}
|
||||
stackContent[total++] = data;
|
||||
}
|
||||
|
||||
public E pop() {
|
||||
if (!isEmpty()) {
|
||||
E datum = stackContent[total];
|
||||
stackContent[total--] = null;
|
||||
return datum;
|
||||
}
|
||||
return null;
|
||||
}
|
||||
|
||||
private void resize(int capacity) {
|
||||
Arrays.copyOf(stackContent, capacity);
|
||||
}
|
||||
|
||||
public boolean isEmpty() {
|
||||
return total == 0;
|
||||
}
|
||||
}
|
||||
@@ -1,13 +0,0 @@
|
||||
package com.baeldung.typeerasure;
|
||||
|
||||
public class IntegerStack extends Stack<Integer> {
|
||||
|
||||
public IntegerStack(int capacity) {
|
||||
super(capacity);
|
||||
}
|
||||
|
||||
public void push(Integer value) {
|
||||
System.out.println("Pushing into my integerStack");
|
||||
super.push(value);
|
||||
}
|
||||
}
|
||||
@@ -1,39 +0,0 @@
|
||||
package com.baeldung.typeerasure;
|
||||
|
||||
import java.util.Arrays;
|
||||
|
||||
public class Stack<E> {
|
||||
|
||||
private E[] stackContent;
|
||||
private int total;
|
||||
|
||||
public Stack(int capacity) {
|
||||
this.stackContent = (E[]) new Object[capacity];
|
||||
}
|
||||
|
||||
public void push(E data) {
|
||||
System.out.println("In base stack push#");
|
||||
if (total == stackContent.length) {
|
||||
resize(2 * stackContent.length);
|
||||
}
|
||||
stackContent[total++] = data;
|
||||
}
|
||||
|
||||
public E pop() {
|
||||
if (!isEmpty()) {
|
||||
E datum = stackContent[total];
|
||||
stackContent[total--] = null;
|
||||
return datum;
|
||||
}
|
||||
return null;
|
||||
}
|
||||
|
||||
private void resize(int capacity) {
|
||||
Arrays.copyOf(stackContent, capacity);
|
||||
}
|
||||
|
||||
public boolean isEmpty() {
|
||||
return total == 0;
|
||||
}
|
||||
|
||||
}
|
||||
Reference in New Issue
Block a user