Java 在Android Studio上创建意图时出错

使用

导入android.content.Intent在主
.java
文件和清单上解决了我的问题，但在第二个
.java
文件中没有

代码如下：

package com.tutorial.helloworld;

import android.os.Bundle;
import android.util.Log;
import android.content.Intent;

public class SecondActivity extends Activity {

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

        String varString = getIntent().getStringExtra("Test");
        Log.d("HelloWorld - Second Activity", varString);
    }
}

以下是错误：

G:\Crear_Apps\Projects\HelloWorld\app\src\main\java\com\tutorial\helloworld\SecondActivity.java

Error:(6, 37) error: cannot find symbol class Activity

Error:(8, 5) error: method does not override or implement a method from a supertype

Error:(10, 9) error: cannot find symbol variable super

Error:(11, 9) error: cannot find symbol method setContentView(int)

Error:(13, 28) error: cannot find symbol method getIntent()


我按照一个教程的步骤操作，在创建“意图”时出错，我搜索了解决方案，但没有任何效果，idk如果是因为Android Studio出现了错误或是我的错误，我也重新启动了Android Studio，但什么也没有发生

MyActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my);
    Log.d("HelloWorld","onCreate");

    Intent i = new Intent(this, SecondActivity.class);
    i.putExtra("Test","true");

    startActivity(i);
}

public class SecondActivity extends Activity{

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

        String varString = getIntent().getStringExtra("Test");
        Log.d("HelloWorld - Second Activity",varString);
    }
}

SecondActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my);
    Log.d("HelloWorld","onCreate");

    Intent i = new Intent(this, SecondActivity.class);
    i.putExtra("Test","true");

    startActivity(i);
}

public class SecondActivity extends Activity{

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

        String varString = getIntent().getStringExtra("Test");
        Log.d("HelloWorld - Second Activity",varString);
    }
}

AndroidManifest.xml

        </activity>
            <activity android:name="com.tutorial.helloworld.SecondActivity">
            </activity>
    </application>

尝试此代码..您应该使用
MyActivity.this
而不仅仅是
this
同时同步android studio一次，清理并重建项目

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my);
    Log.d("HelloWorld","onCreate");

    Intent i = new Intent(MyActivity.this, SecondActivity.class);
    i.putExtra("Test","true");

   startActivity(i);
}

改变这个

对此

进口

您是否使用导入android.content.Intent？确保Android Studio自动导入您使用的类。看起来您没有使用包导入/没有安装适当的sdk。向我们展示这两项活动的完整代码。我们不会在问题中给出答案；谢谢。同步是同步按钮吗？
    </activity>
    <activity android:name=".SecondActivity">
    </activity>
    </application>

    public class SecondActivity extends Activity

    public class SecondActivity extends AppCompatActivity

    import android.support.v7.app.AppCompatActivity;
    import android.content.Intent;