9.19

package com.example.myapp;

 

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;

import android.widget.TextView;

 

public class SecondActivity extends AppCompatActivity {

 

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_second);

 

        // 获取传递的数据

        TextView textView = findViewById(R.id.textView);

        String message = getIntent().getStringExtra("EXTRA_MESSAGE");

        textView.setText(message);

    }

}

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    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="This is the Second Activity" />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent">

 

    <Button

        android:id="@+id/button"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_centerInParent="true"

        android:text="Go to Second Activity" />

</RelativeLayout>

package com.example.myapp;

 

import android.content.Intent;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import androidx.appcompat.app.AppCompatActivity;

 

public class MainActivity extends AppCompatActivity {

 

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

 

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

        button.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                // 创建Intent对象，启动SecondActivity

                Intent intent = new Intent(MainActivity.this, SecondActivity.class);

                // 传递数据

                intent.putExtra("EXTRA_MESSAGE", "Hello from MainActivity!");

                startActivity(intent);

            }

        });

    }

}