以下代码输出结果为：

class Main {
    public static void main(String args[]) { 
        System.out.println(fun());
    } 

    int fun()
    {
        return 20;
    }
}

以下代码输出结果为：

public class Main { 
    public static void main(String args[]) { 
       String x = null; 
       giveMeAString(x); 
       System.out.println(x); 
    } 
    static void giveMeAString(String y) 
    { 
       y = "RUNCODEX"; 
    } 
}

以下代码输出结果为：

class Main {
public static void swap(Integer i, Integer j) {
      Integer temp = new Integer(i);
      i = j;
      j = temp;
   }
   public static void main(String[] args) {
      Integer i = new Integer(10);
      Integer j = new Integer(20);
      swap(i, j);
      System.out.println("i = " + i + ", j = " + j);
   }
}

以下代码输出结果为：

class intWrap {
   int x;
} 
public class Main { 
    public static void main(String[] args) {
       intWrap i = new intWrap();
       i.x = 10;
       intWrap j = new intWrap();
       j.x = 20;
       swap(i, j);
       System.out.println("i.x = " + i.x + ", j.x = " + j.x);
    } 
    public static void swap(intWrap i, intWrap j) {
       int temp = i.x;
       i.x = j.x;
       j.x = temp;
    }
}

以下代码输出结果为：

class Main {
    public static void main(String args[]) {   
        System.out.println(fun());
    }   
    static int fun(int x = 0)
    {
        return x;
    }
}

以下代码输出结果为：

class Test
{
    public void demo(String str)
    {
        String[] arr = str.split(";");
        for (String s : arr)
        {
            System.out.println(s);
        }
    }
 
    public static void main(String[] args)
    {
        char array[] = {'a', 'b', ' ', 'c', 'd', ';', 'e', 'f', ' ', 
                        'g', 'h', ';', 'i', 'j', ' ', 'k', 'l'};
        String str = new String(array);
        Test obj = new Test();
        obj.demo(str);
    }
}

以下代码输出结果为：

class Main
{
    public static void main(String[] args)
    {
        StringBuffer a = new StringBuffer("runnob");
        StringBuffer b = new StringBuffer("com");
        a.delete(1,3);
        a.append(b);
        System.out.println(a);
    }
}

以下代码输出结果为：

class Main
{
    public static void main(String[] args)
    {
        String obj1 = new String("runcodex");
        String obj2 = new String("runcodex");
 
        if(obj1.hashCode() == obj2.hashCode())
            System.out.println("object1 与 object2 哈希码相等");
 
        if(obj1 == obj2)
            System.out.println("object1 与 object2 内存地址一样");
 
        if(obj1.equals(obj2))
            System.out.println("object1 与 object2 值相等");
    }
}

以下代码输出结果为：

class Test implements Cloneable
{
    int a;
 
    Test cloning()
    {
        try
        {
            return (Test) super.clone();
        }
        catch(CloneNotSupportedException e)
        {
            System.out.println("CloneNotSupportedException is caught");
            return this;
        }
    }
}
 
class Main
{
 
    public static void main(String args[])
    {
        Test obj1 = new Test();
        Test obj2;
        obj1.a = 10;
        obj2 = obj1.cloning();
        obj2.a = 20;
 
        System.out.println("obj1.a = " + obj1.a);
        System.out.println("obj2.a = " + obj2.a);
    }
}

以下代码输出结果为：

class Main
{
    public static void main(String[] args)
    {
        String str = "runcodex";
        str.toUpperCase();
        str += "wwwruncodexcom";
        String string = str.substring(2,13);
        string = string + str.charAt(4);;
        System.out.println(string);
    }
}