public class MyUtil {    public static String PErcentage2fivegrade(int grade){        if (grade<0)            return "错误";        //如果成绩小于60，转成“不及格”        else if (grade<60)            return "不及格";        //如果成绩在60与70之间，转成“及格”        else if (grade<70)            return "及格";        //如果成绩在70与80之间，转成“中等”        else if (grade<80)            return "中等";        //如果成绩在80与90之间，转成“良好”        else if (grade<90)            return "良好";        //如果成绩在90与100之间，转成“优秀”        else if (grade<=100)            return "优秀";        //如果成绩大于100，转成“错误"        else            return "错误";    }}

public class MyUtiltest {    @Test    public void testNormal() {        Assert.assertEquals("不及格", MyUtil.percentage2fivegrade(55));        Assert.assertEquals("及格", MyUtil.percentage2fivegrade(65));        Assert.assertEquals("中等", MyUtil.percentage2fivegrade(75));        Assert.assertEquals("良好", MyUtil.percentage2fivegrade(85));        Assert.assertEquals("优秀", MyUtil.percentage2fivegrade(95));    }    @Test    public void testException(){        Assert.assertEquals("错误", MyUtil.percentage2fivegrade(-55));        Assert.assertEquals("不及格", MyUtil.percentage2fivegrade(55));    }    @Test    public void testBoundary(){        Assert.assertEquals("不及格", MyUtil.percentage2fivegrade(0));        Assert.assertEquals("及格", MyUtil.percentage2fivegrade(60));        Assert.assertEquals("中等", MyUtil.percentage2fivegrade(70));        Assert.assertEquals("良好", MyUtil.percentage2fivegrade(80));        Assert.assertEquals("优秀", MyUtil.percentage2fivegrade(90));        Assert.assertEquals("优秀", MyUtil.percentage2fivegrade(100));    }}

import junIT.framework.TestCase;
import static org.junit.Assert.*;
import org.junit.Test;
public class StringBufferDemoTest extends TestCase {
    StringBuffer a = new StringBuffer("stringbuffer");//测试12个字符(<=16)
    StringBuffer b = new StringBuffer("stringbufferstringbuffer");//测试24个字符(>16&&(=34)
    StringBuffer c = new StringBuffer("stringbufferstringbufferstringbuffer");//测试36个字符(>=34)
    @Test
    public void testcharAt() throws Exception {
        assertEquals('s', a.charAt(0));
        assertEquals('g', a.charAt(5));
        assertEquals('r', a.charAt(11));
    }
    @Test
    public void testcapacity() throws Exception {
        assertEquals(28, a.capacity());
        assertEquals(40, b.capacity());
        assertEquals(52, c.capacity());
    }
    @Test
    public void testlength() throws Exception {
        assertEquals(12, a.length());
        assertEquals(24, b.length());
        assertEquals(36, c.length());
    }
    @Test
    public void testindexOf() throws Exception {
        assertEquals(0, a.indexOf("str"));
        assertEquals(5, b.indexOf("gbu"));
        assertEquals(8, c.indexOf("ff"));
    }
}

public class StringBufferDemo {
	public static void main(String [] args){
            StringBuffer buffer = new StringBuffer(20);
            buffer.append('S');
            buffer.append("tringBuffer");
            //		System.out.PRintln(buffer.charAt(1));
            System.out.println(buffer.capacity());
            //		System.out.println(buffer.indexOf("tring12345"));
            System.out.println("buffer = " + buffer.toString());
            System.out.println(buffer.length());
    }
}