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我目前正在开发一个应用程序，在应用程序内部，我需要绘制一些折线图。我研究并找到了一个工具，但问题如下：

public class graphActivity extends AppCompatActivity {

GraphView graph;

SharedPrefManager sharedPrefManager = new SharedPrefManager();

int exercisePosition;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_graph);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    //getting the exercise position from caller activity and proceeding 
    //accordingly...
    if(savedInstanceState == null){
        Bundle extras = getIntent().getExtras();
        if(extras == null){
            //do nothing
        } else{
            exercisePosition = extras.getInt("position");

        }
    } else{
        exercisePosition = (int) savedInstanceState.getSerializable("position");
    }

    graph = (GraphView) findViewById(R.id.graph);

    ArrayList<Exercise> exercises= sharedPrefManager.readSharedPref(this);

    //getting the exercise from exercises array list so that the specific graph for the exercise can be shown.
    Exercise exercise = exercises.get(exercisePosition);


    LineGraphSeries<DataPoint> series = new LineGraphSeries<>(new DataPoint[] {
            //need to put for loop here but I can't...
            //new DataPoint(x,y);
    });

    graph.addSeries(series);



    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}

}

确切地说，我需要使用 for 循环填充 DataPoint 变量，因为数据将由用户输入，但是当我尝试实现 for 循环时它会生气，我不知道如何解决它。如果有人在任何帮助之前处理过这种事情，我们将不胜感激。

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2 回答 2

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做这样的事情，

DataPoint[] dp = new DataPoint[10];
for(int i=1;i<=10;i++){
    dp[i] = new DataPoint(x, y);
}

LineGraphSeries<DataPoint> series = new LineGraphSeries<>(dp);
于 2017-07-27T12:56:21.987 回答
0

如果您不知道您将拥有多少个 DataPoint，您可以使用 ArrayList：

        if (cursor.moveToFirst()) {
            List<DataPoint> dataPoints = new ArrayList<DataPoint>();
            do {
                dataPoints.add(
                    new DataPoint(cursor.getInt(0),
                              cursor.getInt(1)));

            } while (cursor.moveToNext());

            LineGraphSeries<DataPoint> series = new LineGraphSeries<>(
                dataPoints.toArray(new DataPoint[0]));
        }
于 2017-12-03T02:11:49.363 回答