GraphView-我看不到自己的设计

Question

我对GraphView有问题。我在Activity_main中看不到我的设计。取而代之，我看到以下句子“ GraphView：无可用预览”

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
...



</androidx.constraintlayout.widget.ConstraintLayout>

build.gradle

apply plugin: 'com.android.application'

...
dependencies {
   ...
    implementation 'com.jjoe64:graphview:4.2.2'
}

寻求帮助

Mathiew