Java 在Android应用程序中单击CardView不会打开活动，而是会导致应用程序崩溃

我是Android开发的新手，刚刚用Java启动了我的第一个Android应用程序。我的应用程序是关于单位转换的，包括显示要转换单位的数量的卡片视图。单击CardView时，用户应被引导到转换发生的部分，但可以看到，单击CardView时，应用程序崩溃。请对这个问题提出适当的解决办法。 MainActivity.java代码- 包com.example.unitconversionapp

import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.view.View;

import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;
import androidx.cardview.widget.CardView;

public class MainActivity extends AppCompatActivity {

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    void setActivityTemperature(View view) {
        CardView card_view = findViewById(R.id.temperature_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }

    void setActivityArea(View view) {
        CardView card_view = findViewById(R.id.area_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }

    void setActivityTime(View view) {
        CardView card_view = findViewById(R.id.time_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }

    void setActivitySpeed(View view) {
        CardView card_view = findViewById(R.id.speed_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }

    void setActivityWeight(View view) {
        CardView card_view = findViewById(R.id.weight_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }

    void setActivityEnergy(View view) {
        CardView card_view = findViewById(R.id.energy_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }

    void setActivityAngle(View view) {
        CardView card_view = findViewById(R.id.angle_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }

    void setActivityLength(View view) {
        CardView card_view = findViewById(R.id.length_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }

    void setActivityVolume(View view) {
        CardView card_view = findViewById(R.id.volume_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }

    void setActivityCurrency(View view) {
        CardView card_view = findViewById(R.id.currency_card);
        card_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
                Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
                startActivity(intent);
            }
        });
    }
}

XML代码-

    <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:textAlignment="center"
    tools:context=".MainActivity">

    <androidx.cardview.widget.CardView
        android:id="@+id/speed_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="12dp"
        android:onClick="setActivitySpeed"
        app:cardBackgroundColor="@color/colorAccent"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/volume_card">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Speed" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:id="@+id/angle_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="12dp"
        android:onClick="setActivityAngle"
        app:cardBackgroundColor="@color/colorPrimary"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/area_card">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Angle" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:id="@+id/time_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="12dp"
        android:onClick="setActivityTime"
        app:cardBackgroundColor="@android:color/holo_purple"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:cardMaxElevation="25dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/angle_card">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView3"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Time" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:id="@+id/volume_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="12dp"
        android:onClick="setActivityVolume"
        app:cardBackgroundColor="@color/colorPrimaryDark"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/currency_card">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView4"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Volume" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:id="@+id/area_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="12dp"
        android:onClick="setActivityArea"
        app:cardBackgroundColor="@android:color/holo_red_light"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/length_card">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView5"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Area" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:id="@+id/currency_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="12dp"
        android:onClick="setActivityCurrency"
        app:cardBackgroundColor="@android:color/holo_red_dark"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/weight_card">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView6"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Currency" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:id="@+id/weight_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="19dp"
        android:onClick="setActivityWeight"
        app:cardBackgroundColor="@android:color/holo_green_light"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/my_toolbar">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView7"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Weight" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/my_toolbar"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:background="@color/colorToolbar"
        android:minHeight="?attr/actionBarSize"
        android:theme="?attr/actionBarTheme"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:subtitleTextColor="#FFFFFF"
        app:title="Unit Conversion"
        app:titleTextColor="#FFFFFF" />

    <androidx.cardview.widget.CardView
        android:id="@+id/temperature_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="19dp"
        android:onClick="setActivityTemperature"
        app:cardBackgroundColor="@android:color/holo_orange_dark"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/my_toolbar">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:onClick="setActivityTemperature">

            <TextView
                android:id="@+id/textView8"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Temperature" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:id="@+id/length_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="12dp"
        android:onClick="setActivityLength"
        app:cardBackgroundColor="@android:color/holo_blue_dark"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/temperature_card">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView9"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Length" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

    <androidx.cardview.widget.CardView
        android:id="@+id/energy_card"
        android:layout_width="200dp"
        android:layout_height="110dp"
        android:layout_marginTop="12dp"
        android:onClick="setActivityEnergy"
        app:cardBackgroundColor="?attr/colorError"
        app:cardCornerRadius="25dp"
        app:cardElevation="25dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/speed_card">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView10"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Energy" />
        </RelativeLayout>
    </androidx.cardview.widget.CardView>

</androidx.constraintlayout.widget.ConstraintLayout>

---

您仅在温度、角度、重量和体积

cardwiews

中设置了

android:onClick

属性。您还应将其包含在

卡片视图的其余部分中，以实现其各自的功能。并像这样公开所有功能
public void setActivityWeight（View-View）{..}
。
无需再次在java代码中设置侦听器，因为XML中已经有了
OnClick
属性。所以你喜欢这样：-

public void setActivityWeight(View view) {
        CardView card_view = (CardView) view;
        // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }

因此，您的主要活动将如下所示


MainActivity.java

package com.example.sample;

import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;
import androidx.cardview.widget.CardView;

public class MainActivity extends AppCompatActivity {

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void setActivityTemperature(View view) {
        CardView card_view = (CardView) view;
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }

    public void setActivityArea(View view) {
        CardView card_view = (CardView) view;
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }

    public void setActivityTime(View view) {
        CardView card_view = (CardView) view;
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }

    public void setActivitySpeed(View view) {
        CardView card_view = (CardView) view;
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }

    public void setActivityWeight(View view) {
        CardView card_view = (CardView) view;
        // do whatever you want to do on click (to launch any fragment or activity you need to put intent here.)
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }

    public void setActivityEnergy(View view) {
        CardView card_view = (CardView) view;
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }

    public void setActivityAngle(View view) {
        CardView card_view = (CardView) view;
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }


    public void setActivityVolume(View view) {
        CardView card_view = (CardView) view;
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }

    public void setActivityCurrency(View view) {
        CardView card_view = (CardView) view;
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }

    public void setActivityLength(View view) {
        CardView card_view = (CardView) view;
        Intent intent = new Intent(MainActivity.this, ActivityTemperature.class);
        startActivity(intent);
    }
}




还要确保将新活动包括在清单文件中

清单

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Sample">
    <activity android:name="MainActivity"
        android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
        <activity android:name=".ActivityTemperature"/>
    </application>
</manifest>





我已经尝试并测试了这段代码，目前运行良好。发布错误StackTrace不要在
XML
文件中使用
onClick
，尝试在
java
文件中创建卡片视图的对象，然后将
onClickListner
添加到其中。我也面临着类似的问题。@NadeemSheikh完成了，但仍然面临着同样的问题。顺便说一下，我已经编辑了这篇文章，并根据您的请求添加了错误stacktrace。请看一看it@NadeemSheikh Done@RigvedAlankar嘿，检查答案。我已经更新了它。@NademSheikh我根据您的请求公开了所有功能，但我仍然面临着同样的问题。@NadeemSheikh成功了。我忘了提到清单文件中的活动了。非常感谢你，不是。。。请补充一些解释。。。
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        **//try this one (Call the function with the current class context, hope that would might help! )**
        setActivityWeight(this);
    }

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

        **//try this one (Call the function with the current class context, hope that would might help! )**
        setActivityWeight(this);
    }