java - 如何在数据点上添加点击监听器？

Question

我想在 Android Studio 的图形 View 中的数据点上添加点击监听器。

我的 Java 代码中存在一个问题:无法解析最后一行代码中的方法 get Activity()。

帮我解决我的问题。

这是我的代码:

package com.example.graph;

import android.content.Context;
import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;
import android.app.Activity;

import com.jjoe64.graphview.GraphView;
import com.jjoe64.graphview.series.DataPoint;
import com.jjoe64.graphview.series.DataPointInterface;
import com.jjoe64.graphview.series.LineGraphSeries;
import com.jjoe64.graphview.series.OnDataPointTapListener;
import com.jjoe64.graphview.series.PointsGraphSeries;
import com.jjoe64.graphview.series.Series;

public class MainActivity extends AppCompatActivity {

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

        GraphView graph = (GraphView) findViewById(R.id.graph);
        LineGraphSeries<DataPoint> series = new LineGraphSeries<>(new DataPoint[] {
            new DataPoint(0, -2),
            new DataPoint(1, 5),
            new DataPoint(2, 3),
            new DataPoint(3, 2),
            new DataPoint(4, 6)
        });
        graph.addSeries(series);
        graph.setBackgroundColor(getResources().getColor(R.color.background_color));
        series.setThickness(5);
        graph.getViewport().setScalable(true);
        graph.getViewport().setScrollable(true);

        PointsGraphSeries<DataPoint> series2 = new PointsGraphSeries<>(new DataPoint[] {
            new DataPoint(0, -2),
            new DataPoint(1, 5),
            new DataPoint(2, 3),
            new DataPoint(3, 2),
            new DataPoint(4, 6)
        });
        graph.addSeries(series2);
        series2.setColor(Color.RED);
        series2.setSize(10);
        series2.setOnDataPointTapListener(new OnDataPointTapListener() {
            @Override
            public void onTap(Series series2, DataPointInterface dataPoint) {
                Toast.makeText(getActivity(), "Series1: On Data Point clicked: "+dataPoint, Toast.LENGTH_SHORT).show();
            }
        });
    }
}

Answer 1

您的OnDataPointTapListener 是一个匿名类，在该类中不存在getActivity 方法，但它确实在您的Activity 中退出。您应该使用 MainActivity 中的 this 而不是 OnDataPointTapListener 中的 this:

Toast.makeText(MainActivity.this.getActivity(), "Series1: On Data Point clicked: "+dataPoint, Toast.LENGTH_SHORT).show();