2位数的计算结果不会显示答案

Question

我正在尝试做一个简单的2位乘法屏幕，而且我无法实际显示答案。我知道它可能是小而愚蠢的东西。而且由于我对EditText/TextView的用法感到困惑，如果它与这些东西有关，我不会感到惊讶。以下是我迄今为止：

import android.widget.EditText; 
import android.widget.TextView; 
import android.widget.Button; 
import android.os.Bundle; 
import android.view.View; 

public class Multiply extends Index 

{ 

    private EditText amount1; 
    private EditText amount2; 
    private TextView answer; 
    private Button calculate; 
    private double x=0; 
    private double y=0; 
    private double z=0; 
/** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) 
    { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.calc); 
     initControls(); 
    } 

    public void initControls() 
    { 
      amount1=(EditText)findViewById(R.id.amount1); 
      amount2=(EditText)findViewById(R.id.amount2); 
      answer=(TextView)findViewById(R.id.answer); 
      calculate=(Button)findViewById(R.id.calculate); 
      calculate.setOnClickListener(new Button.OnClickListener() 
      { 
       public void onClick(View v) 
       { 
        calculate(); 
       } 
      } 
     ); 
    } 
    private void calculate() 
    { 
      x=Double.parseDouble(amount1.getText().toString()); 
      y=Double.parseDouble(amount2.getText().toString()); 
      z= x*y; 
      answer.setText(Double.toString(z)); 

    } 
} 

的XML文件的“肉”陪这个样子：

<EditText 
     android:id="@+id/amount1" 
     android:layout_height="wrap_content" 
     android:layout_width="50dip"> 
    </EditText> 

    <EditText 
     android:id="@+id/amount2" 
     android:layout_height="wrap_content" 
     android:layout_width="50dip"> 
    </EditText> 

    <Button 
     android:id="@+id/calculate" 
     android:text="CALCULATE" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content"> 
    </Button> 

    <TextView 
     android:id="@+id/answer" 
     android:layout_height="wrap_content" 
     android:layout_width="50dip"> 
    </TextView> 

Answer 1

你的代码是完全正常的，它是工作

只是改变扩展指数扩展活动

package com.test; 

import android.app.Activity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.TextView; 

public class Multiply extends Activity 

{ 

private EditText amount1; 
private EditText amount2; 
private TextView answer; 
private Button calculate; 
private double x=0; 
private double y=0; 
private double z=0; 
/** Called when the activity is first created. */ 
@Override 
public void onCreate(Bundle savedInstanceState) 
{ 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
    initControls(); 
} 

public void initControls() 
{ 
     amount1=(EditText)findViewById(R.id.amount1); 
     amount2=(EditText)findViewById(R.id.amount2); 
     answer=(TextView)findViewById(R.id.answer); 
     calculate=(Button)findViewById(R.id.calculate); 
     calculate.setOnClickListener(new Button.OnClickListener() 
     { 
      public void onClick(View v) 
      { 
       calculate(); 
      } 
     } 
    ); 
} 
private void calculate() 
{ 
     x=Double.parseDouble(amount1.getText().toString()); 
     y=Double.parseDouble(amount2.getText().toString()); 
     z= x*y; 
     answer.setText(Double.toString(z)); 

} 
}