package test;

/**
 * 字符串判空性能大比较
 * 
 * @author yangzhongying
 * @web http://www.seejoke.com
 * @version 1.0
 */
public class Test {

	String s = "";
	long n = 10000000;

	private void function1() {
		long startTime = System.currentTimeMillis();
		for (long i = 0; i < n; i++) {
			if (s == null || s.equals(""))
				;
		}
		long endTime = System.currentTimeMillis();
		System.out.println("function 1 use time: " + (endTime - startTime)
				+ "ms");
	}

	private void function2() {
		long startTime = System.currentTimeMillis();
		for (long i = 0; i < n; i++) {
			if (s == null || s.length() <= 0)
				;
		}
		long endTime = System.currentTimeMillis();
		System.out.println("function 2 use time: " + (endTime - startTime)
				+ "ms");
	}

	private void function3() {
		long startTime = System.currentTimeMillis();
		for (long i = 0; i < n; i++) {
			if (s == null || s.isEmpty())
				;
		}
		long endTime = System.currentTimeMillis();
		System.out.println("function 3 use time: " + (endTime - startTime)
				+ "ms");
	}

	private void function4() {
		long startTime = System.currentTimeMillis();
		for (long i = 0; i < n; i++) {
			if (s == null || s == "")
				;
		}
		long endTime = System.currentTimeMillis();
		System.out.println("function 4 use time: " + (endTime - startTime)
				+ "ms");
	}

	public static void main(String[] args) {
		Test test = new Test();
		test.function1();
		test.function2();
		test.function3();
		test.function4();
	}
}