Java 单击“侦听器”不会切换活动

在android开发中，需要一些从活动切换到活动的帮助。我正在尝试从主活动转到主菜单活动。我实现了一个onclicklistener来完成这项工作。当我在模拟器上运行应用程序时，它运行良好，但是当我单击用onclicklistener实现的按钮时，它什么也不做

package com.example.bmiworking;

import android.app.Activity;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;






            public class MainActivity extends Activity implements OnClickListener{
            /** Called when the activity is first created. */
            Button btn;
            @Override
            public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);
                 btn = (Button)findViewById(R.id.homeClickHandler);
            }
            public void onClick(View v){
                if(v.getId() == R.id.homeClickHandler){
                startActivity(new Intent(this,MainMenu.class));
                }
            }


            public void calculateClickHandler(View view) {
             // make sure we handle the click of the calculator button

             if (view.getId() == R.id.calculateButton) {

              // get the references to the widgets
              EditText weightText = (EditText)findViewById(R.id.weightText);
              EditText heightText = (EditText)findViewById(R.id.heightText);
              TextView resultText = (TextView)findViewById(R.id.resultLabel);

              // get the users values from the widget references

              float weight = Float.parseFloat(weightText.getText().toString());
              float height = Float.parseFloat(heightText.getText().toString());

              // calculate the bmi value

              float bmiValue = calculateBMI(weight, height);

              // interpret the meaning of the bmi value
              String bmiInterpretation = interpretBMI(bmiValue);

              // now set the value in the result text

              resultText.setText(bmiValue + "-" + bmiInterpretation);
             }
            }

            // the formula to calculate the BMI index

            // check for http://en.wikipedia.org/wiki/Body_mass_index
            private float calculateBMI (float weight, float height) {

             return (float) (weight * 4.88 / (height * height));
            }


            // interpret what BMI means
            private String interpretBMI(float bmiValue) {

             if (bmiValue < 16) {
              return "Severely Underweight - See Weight Gain";
             } else if (bmiValue < 18.5) {

              return "Underweight - See Weight Gain";
             } else if (bmiValue < 25) {

              return "Normal - No Recomendations";
             } else if (bmiValue < 30) {

              return "Overweight - See Weight Loss";
             } else {
              return "Obese - See Weight Loss";
             }

            }


            @Override
            public void onClick(DialogInterface arg0, int arg1) {
                // TODO Auto-generated method stub

            }
        }



     <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity" >

        <TextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentTop="true"
            android:layout_centerHorizontal="true"
            android:text="BMI Calculator"
            android:textAppearance="?android:attr/textAppearanceLarge" />

        <EditText
            android:id="@+id/weightText"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/textView2"
            android:layout_centerHorizontal="true"
            android:ems="10"
            android:inputType="numberDecimal" >

            <requestFocus />
        </EditText>

        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/textView1"
            android:layout_centerHorizontal="true"
            android:text="@string/weightLabel"
            android:textAppearance="?android:attr/textAppearanceMedium" />

        <TextView
            android:id="@+id/textView3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/weightText"
            android:layout_centerHorizontal="true"
            android:text="@string/heightLabel"
            android:textAppearance="?android:attr/textAppearanceMedium" />

        <EditText
            android:id="@+id/heightText"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignLeft="@+id/weightText"
            android:layout_below="@+id/textView3"
            android:ems="10"
            android:inputType="numberDecimal" />

        <Button
            android:id="@+id/calculateButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/heightText"
            android:layout_centerHorizontal="true"
            android:onClick="calculateClickHandler"
            android:text="@string/calculateButton" />

        <TextView
            android:id="@+id/resultLabel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_below="@+id/calculateButton"
            android:layout_marginLeft="30dp"
            android:layout_marginTop="15dp"
            android:text="@string/emptyString"
            android:textAppearance="?android:attr/textAppearanceLarge" />

        <Button
            android:id="@+id/homeClickHandler"
            style="?android:attr/buttonStyleSmall"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignParentTop="true"
            android:text="@string/homeButton" />

    </RelativeLayout>

    <?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
        package="com.example.bmiworking"
        android:versionCode="1"
        android:versionName="1.0" >

        <uses-sdk
            android:minSdkVersion="8"
            android:targetSdkVersion="17" />

        <application
            android:allowBackup="true"
            android:icon="@drawable/ic_launcher"
            android:label="@string/app_name"
            android:theme="@style/AppTheme" >
            <activity
                android:name="com.example.bmiworking.MainActivity"
                android:label="@string/app_name" >
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />

                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
            <activity
                android:name="com.example.bmiworking.MainMenu"
                android:label="@string/app_name" >
                </activity>
        </application>

    </manifest>

package com.example.bmiworking；
导入android.app.Activity；
导入android.content.DialogInterface；
导入android.content.DialogInterface.OnClickListener；
导入android.content.Intent；
导入android.os.Bundle；
导入android.view.view；
导入android.widget.Button；
导入android.widget.EditText；
导入android.widget.TextView；
公共类MainActivity扩展活动实现OnClickListener{
/**在首次创建活动时调用*/
按钮btn；
@凌驾
创建时的公共void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
btn=（按钮）findViewById（R.id.homeClickHandler）；
}
公共void onClick（视图v）{
if（v.getId（）==R.id.homeClickHandler）{
startActivity（新意图（这个，MainMenu.class））；
}
}
public void calculateClickHandler（视图）{
//确保我们处理计算器按钮的点击
if（view.getId（）==R.id.calculateButton）{
//获取小部件的引用
EditText-weightText=（EditText）findViewById（R.id.weightText）；
EditText heightText=（EditText）findViewById（R.id.heightText）；
TextView resultText=（TextView）findViewById（R.id.resultLabel）；
//从小部件引用获取用户值
float-weight=float.parseFloat（weightText.getText（）.toString（））；
float height=float.parseFloat（heightText.getText（）.toString（））；
//计算bmi值
浮动BMI值=计算BMI（体重、身高）；
//解释bmi值的含义
字符串bmi解释=解释bmi（bmi值）；
//现在在结果文本中设置值
resultText.setText（bmiValue+“-”+BMI解释）；
}
}
//计算体重指数的公式
//查证http://en.wikipedia.org/wiki/Body_mass_index
专用浮子计算器BMI（浮子重量、浮子高度）{
返回（浮动）（重量*4.88/（高度*高度））；
}
//解读体重指数的含义
专用字符串解释BMI（浮点BMI值）{
如果（BMI值<16）{
返回“严重体重不足-参见体重增加”；
}否则如果（BMI值<18.5）{
返回“体重不足-参见体重增加”；
}否则如果（BMI值<25）{
返回“正常-无建议”；
}否则如果（BMI值<30）{
返回“超重-参见体重减轻”；
}否则{
返回“肥胖-见体重减轻”；
}
}
@凌驾
公共void onClick（对话框接口arg0，int arg1）{
//TODO自动生成的方法存根
}
}

您导入了错误的onClick Listener，因此请删除该导入，同时删除DialogInterface onClick方法

import android.view.View.OnClickListener;

下面是“btn=（按钮）findViewById（R.id.homeClickHandler）；”和：

完成：

package com.example.bmiworking;

import android.app.Activity;
import android.content.DialogInterface;
import android.view.View.OnClickListener;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener {
/** Called when the activity is first created. */
Button btn;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btn = (Button) findViewById(R.id.homeClickHandler);
    btn.setOnClickListener(this);
}

    @Override
public void onClick(View v) {
    if (v.getId() == R.id.homeClickHandler) {
        startActivity(new Intent(this, MainMenu.class));
    }
}

public void calculateClickHandler(View view) {
    // make sure we handle the click of the calculator button

    if (view.getId() == R.id.calculateButton) {

        // get the references to the widgets
        EditText weightText = (EditText) findViewById(R.id.weightText);
        EditText heightText = (EditText) findViewById(R.id.heightText);
        TextView resultText = (TextView) findViewById(R.id.resultLabel);

        // get the users values from the widget references

        float weight = Float.parseFloat(weightText.getText().toString());
        float height = Float.parseFloat(heightText.getText().toString());

        // calculate the bmi value

        float bmiValue = calculateBMI(weight, height);

        // interpret the meaning of the bmi value
        String bmiInterpretation = interpretBMI(bmiValue);

        // now set the value in the result text

        resultText.setText(bmiValue + "-" + bmiInterpretation);
    }
}

// the formula to calculate the BMI index

// check for http://en.wikipedia.org/wiki/Body_mass_index
private float calculateBMI(float weight, float height) {

    return (float) (weight * 4.88 / (height * height));
}

// interpret what BMI means
private String interpretBMI(float bmiValue) {

    if (bmiValue < 16) {
        return "Severely Underweight - See Weight Gain";
    } else if (bmiValue < 18.5) {

        return "Underweight - See Weight Gain";
    } else if (bmiValue < 25) {

        return "Normal - No Recomendations";
    } else if (bmiValue < 30) {

        return "Overweight - See Weight Loss";
    } else {
        return "Obese - See Weight Loss";
    }

}

}

package com.example.bmiworking；
导入android.app.Activity；
导入android.content.DialogInterface；
导入android.view.view.OnClickListener；
导入android.content.Intent；
导入android.os.Bundle；
导入android.view.view；
导入android.widget.Button；
导入android.widget.EditText；
导入android.widget.TextView；
公共类MainActivity扩展活动实现OnClickListener{
/**在首次创建活动时调用*/
按钮btn；
@凌驾
创建时的公共void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
btn=（按钮）findViewById（R.id.homeClickHandler）；
btn.setOnClickListener（此）；
}
@凌驾
公共void onClick（视图v）{
if（v.getId（）==R.id.homeClickHandler）{
startActivity（新意图（这个，MainMenu.class））；
}
}
public void calculateClickHandler（视图）{
//确保我们处理计算器按钮的点击
if（view.getId（）==R.id.calculateButton）{
//获取小部件的引用
EditText-weightText=（EditText）findViewById（R.id.weightText）；
EditText heightText=（EditText）findViewById（R.id.heightText）；
TextView resultText=（TextView）findViewById（R.id.resultLabel）；
//从小部件引用获取用户值
float-weight=float.parseFloat（weightText.getText（）.toString（））；
float height=float.parseFloat（heightText.getText（）.toString（））；
//计算bmi值
浮动BMI值=计算BMI（体重、身高）；
//解释bmi值的含义
字符串bmi解释=解释bmi（bmi值）；
//现在在结果文本中设置值
resultText.setText（bmiValue+“-”+BMI解释）；
}
}
//计算体重指数的公式
//查证http://en.wikipedia.org/wiki/Body_mass_index
专用浮子计算器BMI（浮子重量、浮子高度）{
返回（浮动）（重量*4.88/（高度*高度））；
}
//解读体重指数的含义
私人字符串i
package com.example.bmiworking;

import android.app.Activity;
import android.content.DialogInterface;
import android.view.View.OnClickListener;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener {
/** Called when the activity is first created. */
Button btn;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btn = (Button) findViewById(R.id.homeClickHandler);
    btn.setOnClickListener(this);
}

    @Override
public void onClick(View v) {
    if (v.getId() == R.id.homeClickHandler) {
        startActivity(new Intent(this, MainMenu.class));
    }
}

public void calculateClickHandler(View view) {
    // make sure we handle the click of the calculator button

    if (view.getId() == R.id.calculateButton) {

        // get the references to the widgets
        EditText weightText = (EditText) findViewById(R.id.weightText);
        EditText heightText = (EditText) findViewById(R.id.heightText);
        TextView resultText = (TextView) findViewById(R.id.resultLabel);

        // get the users values from the widget references

        float weight = Float.parseFloat(weightText.getText().toString());
        float height = Float.parseFloat(heightText.getText().toString());

        // calculate the bmi value

        float bmiValue = calculateBMI(weight, height);

        // interpret the meaning of the bmi value
        String bmiInterpretation = interpretBMI(bmiValue);

        // now set the value in the result text

        resultText.setText(bmiValue + "-" + bmiInterpretation);
    }
}

// the formula to calculate the BMI index

// check for http://en.wikipedia.org/wiki/Body_mass_index
private float calculateBMI(float weight, float height) {

    return (float) (weight * 4.88 / (height * height));
}

// interpret what BMI means
private String interpretBMI(float bmiValue) {

    if (bmiValue < 16) {
        return "Severely Underweight - See Weight Gain";
    } else if (bmiValue < 18.5) {

        return "Underweight - See Weight Gain";
    } else if (bmiValue < 25) {

        return "Normal - No Recomendations";
    } else if (bmiValue < 30) {

        return "Overweight - See Weight Loss";
    } else {
        return "Obese - See Weight Loss";
    }

}

}