eletest.java

这个是一个计算表达式的java包

package com.singularsys.jeptests.functions;

import org.junit.Assert;
import org.junit.Test;
import com.singularsys.jep.*;

public class EleTest {

	Jep jep;
	
	public EleTest() {
		jep = new Jep();
	}


	@Test
	public void testEle() {

		try {
			jep.parse("x = [1, 2, 3, 4, 5]");
			jep.evaluate();

			// get element values
			ensureValue("x[1]", new Double(1.0));
			ensureValue("x[2]", new Double(2.0));
			ensureValue("x[3]", new Double(3.0));
			ensureValue("x[4]", new Double(4.0));
			ensureValue("x[5]", new Double(5.0));
			ensureValue("x[3-1]", new Double(2.0));
			
			// set elements
			jep.parse("x[1] = 100");
			jep.evaluate();
			ensureValue("x[1]", new Double(100.0));
			
		} catch (Exception e) {
			Assert.fail("Exception thrown:" + e.getMessage());
		}

		// ensure out of bound exceptions
		try {
			jep.parse("x[0]");
		} catch (ParseException e) {
			Assert.fail();
			e.printStackTrace();
		}
		
		try {
			jep.evaluate();
			Assert.fail("Expected exception not received");
		} catch (Exception e) {
		}
		
		// ensure out of bound exceptions
		try {
			jep.parse("x[100]");
		} catch (ParseException e) {
			Assert.fail();
			e.printStackTrace();
		}
		
		try {
			jep.evaluate();
			Assert.fail("Expected exception not received");
		} catch (Exception e) {
		}
	}

	private void ensureValue(String expr, Object value) throws Exception {
		jep.parse(expr);
		Object retval = jep.evaluate();
		if (value instanceof Double) {
			Assert.assertEquals(retval, value);
			System.out.println(expr + " = " + value);
		} else {
			Assert.fail();
		}
	}
}