我正在使用achartengine在我的应用中绘制图表。我在table.xml的表格中声明与Table.java相关联的点。现在我的图表应该得到这些点并使用它们。我的图表以Graph.java编码，并通过Graphdisplay.java进行调用。
EDIT2：我稍微更改了代码。首先，我将Graphdisplay.java中的代码添加到Graph.java的onCreate方法中，并删除了Graphdisplay.java。
其次我在Graph.java的第一个答案中添加了一些get和set方法，例如here，并在onCreate方法中从Table.java获取数据。
第三，我将get方法放在GraphicalView
中 Graph.java:
public class Graph extends Activity{
//only for x1 for now
public double ds_x1;
public Double getX1(){return this.ds_x1;}
public void setX1(Double ds_x1){this.ds_x1=ds_x1;}
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.graph);
//getting the data from Table.java
ds_x1 = getIntent().getExtras().getDouble("s_x1");
Graph line = new Graph();
final GraphicalView gView = line.getView(getApplicationContext());
LinearLayout layout = (LinearLayout) findViewById(R.id.chart);
layout.addView(gView);
}
public GraphicalView getView(Context context) {
Double d_x1 = getX1();
ArrayList<Double> xList = new ArrayList<Double>();
double x1 = d_x1;
xList.add(x1);
double x2 = 2;
xList.add(x2);
double x3 = 3;
xList.add(x3);
ArrayList<Double> yList = new ArrayList<Double>();
double y1 = 1;
yList.add(y1);
double y2 = 2;
yList.add(y2);
double y3 = 3;
yList.add(y3);
XYSeries series = new XYSeries("List");
for (int i = 0; i < xList.size(); i++) {
series.add(i, xList.get(i), yList.get(i));
}
XYMultipleSeriesDataset dataset = new XYMultipleSeriesDataset();
dataset.addSeries(series);
XYSeriesRenderer renderer = new XYSeriesRenderer();
XYMultipleSeriesRenderer mRenderer = new XYMultipleSeriesRenderer();
return ChartFactory.getLineChartView(context, dataset, mRenderer);
}
}
Table.java:现在双倍没有字符串
EditText x1 = (EditText) findViewById(R.id.x1);
EditText x2 = (EditText) findViewById(R.id.x2);
EditText x3 = (EditText) findViewById(R.id.x3);
EditText y1 = (EditText) findViewById(R.id.y1);
EditText y2 = (EditText) findViewById(R.id.y2);
EditText y3 = (EditText) findViewById(R.id.y3);
Button b_continue = (Button) findViewById(R.id.b_continue);
b_continue.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Double s_x1 = Double.parseDouble(x1.getText().toString());
Double s_x2 = Double.parseDouble(x2.getText().toString());
Double s_x3 = Double.parseDouble(x3.getText().toString());
Double s_y1 = Double.parseDouble(y1.getText().toString());
Double s_y2 = Double.parseDouble(y2.getText().toString());
Double s_y3 = Double.parseDouble(y3.getText().toString());
Intent myIntent = new Intent(view.getContext(), Graph.class);
myIntent.putExtra("s_x1", s_x1);
myIntent.putExtra("s_x2", s_x2);
myIntent.putExtra("s_x3", s_x3);
myIntent.putExtra("s_y1", s_y1);
myIntent.putExtra("s_y2", s_y2);
myIntent.putExtra("s_y3", s_y3);
startActivity(myIntent);
}
});
logcat的：
08-29 14:31:00.720 17322-17322/test.com.myApp E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity
ComponentInfo{test.com.myApp/test.com.myApp.Graph}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2295)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)
at android.app.ActivityThread.access$700(ActivityThread.java:159)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:176)
at android.app.ActivityThread.main(ActivityThread.java:5419)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at test.com.myApp.Graph.getView(Graph.java:96)
at test.com.myApp.Graph.onCreate(Graph.java:44)
at android.app.Activity.performCreate(Activity.java:5372)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2257)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)
at android.app.ActivityThread.access$700(ActivityThread.java:159)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:176)
at android.app.ActivityThread.main(ActivityThread.java:5419)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
at dalvik.system.NativeStart.main(Native Method)
问题：点击按钮进入图表时，应用程序崩溃，而不是显示带有值的图表！我发现问题在于它不是像double double = 5.0这样的定义值。 aChartEngine在表中输入的值存在问题。
答案 0 :(得分：1)
还有一种方法可以为您的意图设置“双重额外”： Intent android.content.Intent.putExtra（String name，double value）
以及获得双倍额外费用的方法： double android.content.Intent.getDoubleExtra（String name，double defaultValue）
所以你不需要解析字符串......
但是，总的来说，这是正确的方法。或者你有特定的问题吗？
编辑： 使用它而不是valueOf：
double y2 = Double.parseDouble（getIntent（）。getStringExtra（“s_y2”））
EDIT2，试试：
Button b_continue = (Button) findViewById(R.id.b_continue);
b_continue.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String s_x1 = x1.getText().toString();
String s_x2 = x2.getText().toString();
String s_x3 = x3.getText().toString();
String s_y1 = y1.getText().toString();
String s_y2 = y2.getText().toString();
String s_y3 = y3.getText().toString();
Intent myIntent2 = new Intent(view.getContext(), Graph.class);
myIntent2.putExtra("s_x1", s_x1);
myIntent2.putExtra("s_x2", s_x2);
myIntent2.putExtra("s_x3", s_x3);
myIntent2.putExtra("s_y1", s_y1);
myIntent2.putExtra("s_y2", s_y2);
myIntent2.putExtra("s_y3", s_y3);
Intent myIntent = new Intent(view.getContext(), Graphdisplay.class);
startActivity(myIntent);
}
});