java基础之"=="操作符

如下：

 

public class Test
{
	public static void main(String[] args)
	{
		Test t = new Test();
		
		t.compare();
		t.compare2();
	}
	
	public void compare()
	{
		//1
		Integer i1 = new Integer(1);
		Integer i2 = new Integer(1);
		Integer i3 = i1;
		
		System.out.println(i1 == i2);
		System.out.println(i1 == i3);
		System.out.println(i1.equals(i2));
		System.out.println();
		
		//2
		Boolean b1 = new Boolean(false);
		Boolean b2 = new Boolean(false);
		Boolean b3 = b1;
		
		System.out.println(b1 == b2);
		System.out.println(b1 == b3);
		System.out.println(b1.equals(b2));
		System.out.println();
		
		//3
		int[] a1 = new int[3];
		int[] a2 = new int[3];
		int[] a3 = a1;
		
		System.out.println(a1 == a2);
		System.out.println(a1 == a3);
		System.out.println(a1.equals(a2));
		System.out.println();
	}
	
	public void compare2()
	{
		TestC tc = new TestC();
		TestB tb = new TestB();
		TestA ta = new TestA();
		
		System.out.println(tc == tb);
		System.out.println(tc == ta);
		
		ta = tb;
		System.out.println(ta == tb);
		
		ta = tc;
		System.out.println(ta == tc);
		
		ta = new TestC();
		System.out.println(ta == tc);
	}
}

class TestC extends TestB
{
	
}

class TestB extends TestA
{
	
}

class TestA
{
	
}

 

 

输出为：

 

false
true
true

false
true
true

false
true
false

false
false
true
true
false