package com.example.handwriting import android.os.Bundle import androidx.activity.ComponentActivity import androidx.activity.compose.setContent import androidx.compose.foundation.layout.fillMaxSize import androidx.compose.material3.MaterialTheme import androidx.compose.material3.Surface import androidx.compose.material3.Text import androidx.compose.runtime.Composable import androidx.compose.ui.Modifier import androidx.compose.ui.tooling.preview.Preview import com.example.handwriting.ui.theme.HandWritingTheme class MainActivity : ComponentActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { HandWritingTheme { // A surface container using the 'background' color from the theme Surface( modifier = Modifier.fillMaxSize(), color = MaterialTheme.colorScheme.background ) { Greeting("Android") } } } } } @Composable fun Greeting(name: String, modifier: Modifier = Modifier) { Text( text = "Hello $name!", modifier = modifier ) } @Preview(showBackground = true) @Composable fun GreetingPreview() { HandWritingTheme { Greeting("Android") } }请加 button click 事件 ，启动新activity

好的，可以尝试添加以下代码，它会在界面上添加一个按钮，点击后启动一个新的 Activity：

import android.content.Intent
import androidx.activity.compose.rememberLauncherForActivityResult
import androidx.activity.result.contract.ActivityResultContracts
import androidx.compose.foundation.layout.Column
import androidx.compose.material3.Button
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
    
setContent {
    val showNewActivity = remember { mutableStateOf(false) }
    val launcher = rememberLauncherForActivityResult(ActivityResultContracts.StartActivityForResult()) { }
    HandWritingTheme {
        Surface(
            modifier = Modifier.fillMaxSize(),
            color = MaterialTheme.colorScheme.background
        ) {
            Column {
                Greeting("Android")
                Button(onClick = { showNewActivity.value = true }) {
                    Text("启动新页面")
                }
                if (showNewActivity.value) {
                    launcher.launch(Intent(this@MainActivity, NewActivity::class.java))
                }
            }
        }
    }
}

class NewActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_new)
    }
}

需要注意的是，为了启动新的 Activity，我们需要在 AndroidManifest.xml 中注册该 Activity。同时，还需要在 res/layout 文件夹下创建一个名为 activity_new.xml 的布局文件，用于显示新的 Activity 界面。