计算 canvas 点在 android 中的距离

Question

我想做 android 个应用程序来计算 android 上 canvas 的距离点。基本上我有 4 个点，(x1,y1)(x2,y2),(x3,y3) and (x4,y4). 我想做的是计算最大长度 D1 与最小长度 D2 的比值。对于 D1，我需要计算两点之间的距离 (x1,y1)(x2,y2)对于 D2，我需要计算另一个点的距离 (x3,y3)(x4,y4).. 对于这些点，它只是用户输入。用户将输入值并直接计算比率 D1/D2。

有人可以帮助我吗？我知道公式但不确定如何执行该功能。

public class MainActivity5 extends Activity implements OnClickListener {

EditText editText1;
EditText editText2;
EditText editText3;
EditText editText4;
EditText editText5;
EditText editText6;
EditText editText7;
EditText editText8;
Button button1;
TextView tvResult;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_activity5);


      // find the elements
    EditText editText1 = (EditText) findViewById(R.id.editText1);
    EditText editText2 = (EditText) findViewById(R.id.editText2);
    EditText editText3 = (EditText) findViewById(R.id.editText3);
    EditText editText4 = (EditText) findViewById(R.id.editText4);
    EditText editText5 = (EditText) findViewById(R.id.editText4);
    EditText editText6 = (EditText) findViewById(R.id.editText5);
    EditText editText7 = (EditText) findViewById(R.id.editText6);
    EditText editText8 = (EditText) findViewById(R.id.editText7);


    button1 = (Button) findViewById(R.id.button1);

    tvResult = (TextView) findViewById(R.id.tvResult);

    // set a listener
    button1.setOnClickListener((OnClickListener) this);
  }

@Override
public void onClick(View arg0) {
    // TODO Auto-generated method stub

 String x1 = editText1.getText().toString();
 String y1 = editText2.getText().toString();
 String x2 = editText3.getText().toString();
 String y2 = editText4.getText().toString();
 String x3 = editText5.getText().toString();
 String y3 = editText6.getText().toString();
 String x4 = editText7.getText().toString();
 String y4 = editText8.getText().toString();

 //calculating distance
 double dist = Math.sqrt(Math.pow(x1 - x2, 2) + Math.pow(y1- y2, 2));

 //what should i put here
 }

Answer 1

您需要先解析字符串，然后才能将它们传递给 Math 方法。 try-catch 块可用于检查无效数字的情况。

public void onClick(View arg0) {
    try {
        double x1 = Double.parseDouble(editText1.getText().toString());
        double y1 = Double.parseDouble(editText2.getText().toString());
        double x2 = Double.parseDouble(editText3.getText().toString());
        double y2 = Double.parseDouble(editText4.getText().toString());
        double x3 = Double.parseDouble(editText5.getText().toString());
        double y3 = Double.parseDouble(editText6.getText().toString());
        double x4 = Double.parseDouble(editText7.getText().toString());
        double y4 = Double.parseDouble(editText8.getText().toString());

        //calculating distance
        double d1 = Math.sqrt(Math.pow(x1 - x2, 2) + Math.pow(y1- y2, 2));
        double d2 = Math.sqrt(Math.pow(x3 - x4, 2) + Math.pow(y3- y4, 2));

        tvResult.setText(Double.toString(d1/d2));
    } catch (NumberFormatException e) {

    }
}

计算 canvas 点在 android 中的距离

calculate the distance of point of canvas in android

java

android

canvas

point

coordinates