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Arrays can store many values at once, but a variable does not store the array, it stores a reference

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that points to it.

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This can introduce a lot of bugs, so it helps to visualize the runtime using breakpoints.

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In this lesson, you're going to learn to debuggers using breakpoints.

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All right, at this point in the course, you're well aware of the reference trap, but it would be

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nice to visualize the reference dropped during runtime.

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So open this file.

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Place breakpoints next to each line of code.

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And you know what, I'm actually going to remove the breakpoints from functions and Lupe's.

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All right, then launched the debugger.

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The verbal greeting stories I reference that points to an array with two string values.

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And by setting farewell equal to greeting farewell copies, that same reference.

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Farewell and greeting cherie reference that points to the same array.

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And so updating the array through farewell effects, greeting.

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And now it's really nice that you can finally see the reference drop in real time, and this is why

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I love this code anyways, this is considered a bug because the application doesn't behave like we expect

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it to, because if we keep stepping into the runtime, that's exactly what happens.

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And the solution, obviously, is to farewell equal to a copy of the Iraq.

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Launch another debugging session.

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The verbal greeting saw as a reference that points to an array with two string values.

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Farewell was a reference that points to a copy of the original array, and so both variables are completely

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independent of each other.

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All right, now, debugging a one dimensional array is easy to erase are a different story.

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So open up upper triangular java and the goal is to produce an upper triangular matrix from the two

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Deira.

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An upper triangular matrix is a two tier with zeros below the main diagonal.

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If you're on the current code.

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It's going to crash.

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First step is to find out why something is wrong and using breakpoints, we can visualize the runtime

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and figure it out.

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Then launch a new debugging session.

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And woops, it seems that every time the inner loop runs or increasing the outer loop counter, eventually

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the outer loop counter exceeds the bounds of the array and crashes the up.

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This mistake is so common and it can happen when you're not paying attention.

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But seeing that runtime helps us debug the problem and see it right away.

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All right, we run the code.

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The nested loop sets every element to zero, that's not good.

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If you look back at the output, only elements below the main diagonal should be zero.

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Now it's hard to keep track of two counters at the same time.

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And so this makes it hard to predict how we're going to use them to achieve our goal.

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But it helps to launch a debugging session to visualize the runtime.

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Hopefully then we can see a pattern.

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And you know what, after visualizing the array without even stepping into the nested loop, the pattern

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is clear.

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The elements that need to be zero have a J index lower than the index.

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So if Jay is smaller than I.

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Then we're going to say matrix age is equal to zero.

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All right, launch another debugging session to visualize the runtime.

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And therein lies the beauty of visual analysis.

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It helps to have a clear visual of what's going on instead of just looking at code.

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And there's your upper triangular matrix.

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In this lesson, you learn to debug using breakpoints now debugging in normal arrays, easy, but the

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usage of a tutera implies a nested loop.

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And so it's hard to keep track of the counters Ingi and how they're affecting your array.

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But when you can visualize the runtime step by step, you can easily see how the state of the tiaro

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is going to change.