Make Junit not stop when assertion fails

Let’s say we have multiple assertion check in one test method, Junit will stop at the first assertion error.

String str = null;
assertNotNull("String str should not be null", str);
str = "";
assertEquals("String str should have the lenght of 1", str.length(), 1);  

I am using Junit class to do WebDriver test. I want to all assertions are executed no matter there is error or not. Junit Error Collector Rule allows me do that.

@Rule
public ErrorCollector errorCollector= new ErrorCollector();

@Test
public doSomeTest() {
    //do something...
    errorCollector.checkThat("penalty", is(savedPage.getPenalty().getValue()));
    errorCollector.checkThat("exclusion", is(savedPage.getExclusion().getValue()));
}

The code above will run all the check no matter there is error or not