java結果輸出，知其所以然 – JAVA編程語言程序開發技術文章

[java] 
代碼輸出結果是什麼？為什麼會出現這種結果？ 
代碼一 
public class ParentTest { 
    public ParentTest(){ 
        System.out.println("Parent Constructor invoked"); 
    } 
    static{ 
        System.out.println("parent static invoked"); 
    } 
     
    { 
        System.out.println("parent invoked"); 
    } 
} 
public class ChildrenTest extends ParentTest{ 
    public ChildrenTest(){ 
        System.out.println("Children Constructor invoked"); 
    } 
    static{ 
        System.out.println("Children static invoked"); 
    } 
     
    { 
        System.out.println("Children invoked"); 
    } 
    public static void main(String[] args) { 
        new ChildrenTest(); 
    } 
} 
代碼二:true or false 
public class MyTest1 { 
    private String str; 
    public MyTest1(String str){ 
        this.str=str; 
    } 
    public static void main(String[] args) { 
        MyTest1 m1=new MyTest1("hello"); 
        MyTest1 m2=new MyTest1("hello"); 
        System.out.println(m1.equals(m2)); 
    } 
} 
代碼三:true or false 
public class MyTest1 { 
    public static void main(String[] args) { 
    System.out.println(Integer.valueOf(323)==Integer.valueOf(323)); 
    System.out.println(Integer.valueOf(23)==Integer.valueOf(23)); 
    } 
} 
代碼四： 
public class MyTest1 { 
    private static int a; 
    public MyTest1(){ 
        System.out.println("a="+(++a)); 
    } 
    public void test(){ 
        int a=5; 
        System.out.println("a="+a); 
    } 
    public void test2(){ 
        a=5; 
        System.out.println("a="+a); 
    } 
    public static void main(String[] args) { 
        new MyTest1(); 
        new MyTest1(); 
        new MyTest1().test(); 
        System.out.println(a); 
        new MyTest1().test2(); 
        System.out.println(a); 
    } 
} 
代碼五： 
public class Parent { 
    public Parent(String name){ 
        System.out.println(name); 
    } 
} 
public class Children extends Parent{ 
    public Children(String name){ 
        System.out.println(name); 
    } 
     
    public static void main(String[] args) { 
        new Children("hello"); 
    } 
} 
作者：HarderXin