用两种编程方法求存储每种Java基本整数类型所需要的位数(不考虑符号)

1.用位移操作

import junit.framework.TestCase;

public class TestDataTypeSize extends TestCase{

	public void testLong(){
		long a= 0;
		int count = 0;
		while(a !=0){
			a = (a << 1);
			count++;
		}
		assertEquals(64, count);
	}
	public void testInt(){
		int a= 0;
		int count = 0;
		while(a !=0){
			a = (a << 1);
			count++;
		}
		assertEquals(32, count);
	}
	public void testShort(){
		short a = 0;
		int count = 0;
		while(a !=0){
			a = (short) (a << 1);
			count++;
		}
		assertEquals(16, count);
	}

	public void testByte(){
		byte a= 0;
		int count = 0;
		while(a !=0){
			a = (byte) (a << 1);
			count++;
		}
		assertEquals(8, count);
	}
}

2.用数据流

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;

import junit.framework.TestCase;


public class TestDataTypeSize extends TestCase {

	public void testLong() throws IOException{
		
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
		DataOutputStream dataOutputStream = new DataOutputStream(byteArrayOutputStream);
		dataOutputStream.writeLong(0);

		assertEquals(8, byteArrayOutputStream.size());
		dataOutputStream.close();

	}
	public void testInt() throws IOException{

		ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
		DataOutputStream dataOutputStream = new DataOutputStream(byteArrayOutputStream);
		dataOutputStream.writeInt(0);
		
		assertEquals(4, byteArrayOutputStream.size());
		dataOutputStream.close();
	}

	public void testShort() throws IOException{
		
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
		DataOutputStream dataOutputStream = new DataOutputStream(byteArrayOutputStream);
		dataOutputStream.writeShort(0);
		
		assertEquals(2, byteArrayOutputStream.size());
		dataOutputStream.close();
	}

	public void testByte() throws IOException{

		ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
		DataOutputStream dataOutputStream = new DataOutputStream(byteArrayOutputStream);
		dataOutputStream.writeByte(0);
	
		assertEquals(1, byteArrayOutputStream.size());
		dataOutputStream.close();
	}

}