计算两点之间的距离

Question

I tried the following code.but it gives two errors.I want calculate the distance between two points by formula line and display the result in the textView1 . I do not know Where did I make the mistake in the code?

Cal.java

    import android.view.View;
import android.content.Context;
import java.lang.Math;

public class Cal extends View {
Cal(Context context){
    super(context);
}
public double result;
double parameter = ((10-80)^2) + ((15-90)^2);
public void cal(){
    result = Math.sqrt(parameter);
}
}

MainActivity.java

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends Activity{
   Cal cal;

    TextView textView;
    public void onCreate(Bundle s){
        super.onCreate(s);
 setContentView(R.id.textView1);
    cal = new Cal(this);
        textView.setText(cal).;
    }
}

Errors:

Gradle: FAILURE: Build failed with an exception.

• What went wrong: Execution failed for task ':Www:compileDebug'.

  Compilation failed; see the compiler error output for details.

• Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

and

Could not execute build using Gradle distribution ' http://services.gradle.org/distributions/gradle-1.6-bin.zip '.

Answer 1

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends Activity{
    Cal cal;
    TextView textView;

    public void onCreate(Bundle s){
    super.onCreate(s);
    setContentView(R.layout.<your layout name>);  // You can not set id of any view here
    cal = new Cal(this);  // This is a object
    cal.cal();
    textView.setText(""+ cal.result);   // set the value instead of view object
    }
}

Answer 2

Make the cal() method return double value:

import android.view.View;
import android.content.Context;
import java.lang.Math;

    public class Cal extends View {
    Cal(Context context){
        super(context);
    }
    public double result;
    double parameter = ((10-80)^2) + ((15-90)^2);
    public double cal(){
        result = Math.sqrt(parameter);
        return result;
    }
    }

Call the cal() method and display the result.

    import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends Activity{
    Cal cal;
    TextView textView;

    public void onCreate(Bundle s){
    super.onCreate(s);
    setContentView(R.layout.<put your layout name here>); 
    cal = new Cal(this);  
    double res = cal.cal();
    textView.setText(""+res);   
    }
}

The textview will be set to " NaN " as your parameter variable is not a number variable.