Intent in = new Intent(getApplicationContext(),SecondaryScreen.class);    
    startActivity(in);

    This is an explicit intent to start secondscreen activity.

虽然已经提供了正确的答案，但我在这里搜索语言Kotlin的答案。这个问题不是关于特定于语言的，所以我添加代码来完成这个任务在Kotlin语言。

下面是如何在Kotlin中为andorid做到这一点

testActivityBtn1.setOnClickListener{
      val intent = Intent(applicationContext,MainActivity::class.java)
      startActivity(intent)

 }

Intent i = new Intent(firstactivity.this, secondactivity.class);
startActivity(i);

在android应用程序中，从另一个活动启动一个活动是非常常见的场景。 要启动一个活动，你需要一个Intent对象。

如何创建意图对象?

意图对象的构造函数中有两个形参

上下文 要启动的活动的名称。(或完整包名)

例子:

例如，如果你有两个活动，说HomeActivity和DetailActivity，你想从HomeActivity启动DetailActivity (HomeActivity—>DetailActivity)。

下面是演示如何启动DetailActivity的代码片段

HomeActivity。

Intent i = new Intent(HomeActivity.this,DetailActivity.class);
startActivity(i);

这样就做完了。

回到按钮点击部分。

Button button = (Button) findViewById(R.id.someid);

button.setOnClickListener(new View.OnClickListener() {
     
     @Override
     public void onClick(View view) {
         Intent i = new Intent(HomeActivity.this,DetailActivity.class);
         startActivity(i);  
      }

});

在发送活动中尝试以下代码

   //EXTRA_MESSAGE is our key and it's value is 'packagename.MESSAGE'
    public static final String EXTRA_MESSAGE = "packageName.MESSAGE";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
       ....

        //Here we declare our send button
        Button sendButton = (Button) findViewById(R.id.send_button);
        sendButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //declare our intent object which takes two parameters, the context and the new activity name

                // the name of the receiving activity is declared in the Intent Constructor
                Intent intent = new Intent(getApplicationContext(), NameOfReceivingActivity.class);

                String sendMessage = "hello world"
                //put the text inside the intent and send it to another Activity
                intent.putExtra(EXTRA_MESSAGE, sendMessage);
                //start the activity
                startActivity(intent);

            }

从接收活动尝试以下代码:

   protected void onCreate(Bundle savedInstanceState) {
 //use the getIntent()method to receive the data from another activity
 Intent intent = getIntent();

//extract the string, with the getStringExtra method
String message = intent.getStringExtra(NewActivityName.EXTRA_MESSAGE);

然后将以下代码添加到AndroidManifest.xml文件中

  android:name="packagename.NameOfTheReceivingActivity"
  android:label="Title of the Activity"
  android:parentActivityName="packagename.NameOfSendingActivity"

点击按钮打开活动的最简单的方法是:

在res文件夹下创建两个活动，在第一个活动中添加一个按钮，并为onclick函数命名。 每个活动应该有两个java文件。 下面是代码:

MainActivity.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.content.Intent;
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void goToAnotherActivity(View view) {
        Intent intent = new Intent(this, SecondActivity.class);
        startActivity(intent);
    }
}

SecondActivity.java

package com.example.myapplication;
import android.app.Activity;
import android.os.Bundle;
public class SecondActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity1);
    }
}

AndroidManifest.xml(只需将此代码块添加到现有代码中)

 </activity>
        <activity android:name=".SecondActivity">
  </activity>