java - Android 按钮不起作用？

Question

我想制作一个应用程序，以英尺和英寸为单位输入，以及每英尺的成本，并计算杆的成本。这是一个非常简单的应用程序，我已经完成了大部分工作，但是当我点击计算 按钮 时，代替“结果”，我的答案应该会出现。

现在是 XML 代码:

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="@string/ft"
    android:id="@+id/feet"
    android:layout_marginTop="41dp"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

<EditText
    android:layout_width="100dp"
    android:layout_height="wrap_content"
    android:id="@+id/feet1"
    android:layout_alignBottom="@+id/feet"
    android:layout_toRightOf="@+id/feet"
    android:inputType="text" />

<EditText
    android:layout_width="100dp"
    android:layout_height="wrap_content"
    android:id="@+id/inches"
    android:layout_alignBottom="@+id/feet"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:inputType="text" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="@string/in"
    android:id="@+id/Inches"
    android:layout_alignBottom="@+id/feet"
    android:layout_toLeftOf="@+id/inches"
    android:layout_toStartOf="@+id/inches" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="@string/cost"
    android:id="@+id/cost"
    android:layout_marginTop="60dp"
    android:layout_below="@+id/feet"
    android:layout_toRightOf="@+id/feet"
    android:layout_toEndOf="@+id/feet" />

<EditText
    android:layout_width="100dp"
    android:layout_height="wrap_content"
    android:id="@+id/calcost"
    android:layout_alignBottom="@+id/cost"
    android:layout_toRightOf="@+id/cost"
    android:layout_toEndOf="@+id/cost"
    android:inputType="text" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/cal"
    android:id="@+id/calculate"
    android:layout_below="@+id/cost"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="73dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="@string/ans"
    android:id="@+id/result"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:layout_marginBottom="123dp" />

Java 代码如下:

package com.example.baqir.saecost;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RelativeLayout;
import android.widget.TextView;


public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}
public void add(View v)
{
    RelativeLayout rel= (RelativeLayout) findViewById(R.id.rel);
    final TextView result= (TextView)findViewById(R.id.result);
    EditText et1= (EditText)findViewById(R.id.feet1);
    EditText et2= (EditText) findViewById(R.id.inches);
    EditText ct= (EditText)findViewById(R.id.calcost);
    final double a=Double.parseDouble(String.valueOf(et1.getText()));
    final double b=Double.parseDouble(String.valueOf(et2.getText()));
    final double c=Double.parseDouble(String.valueOf(ct.getText()));
    final Button button = (Button) findViewById(R.id.calculate);
    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View g) {
                double i;
                i=(a+(b/12))*c;
            result.setText(i+" Rs");
            }
    });
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

Answer 1

像这样更改您的代码:

public void add(View v)
{
    RelativeLayout rel= (RelativeLayout) findViewById(R.id.rel);
    final TextView result= (TextView)findViewById(R.id.result);
    EditText et1= (EditText)findViewById(R.id.feet1);
    EditText et2= (EditText) findViewById(R.id.inches);
    EditText ct= (EditText)findViewById(R.id.calcost);
    final double a=Double.parseDouble(String.valueOf(et1.getText()));
    final double b=Double.parseDouble(String.valueOf(et2.getText()));
    final double c=Double.parseDouble(String.valueOf(ct.getText()));
    final Button button = (Button) findViewById(R.id.calculate);
    // button.setOnClickListener(new View.OnClickListener() {
    //    public void onClick(View g) {
                double i;
                i=(a+(b/12))*c;
            result.setText(i+" Rs");
   //         }
  //  });
}

并在您的 XML 更改中添加 onClick，如:

<Button
    android:onClick="add"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/cal"
    android:id="@+id/calculate"
    android:layout_below="@+id/cost"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="73dp" />