跳转与数据传递

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import org.w3c.dom.Text;

public class MainActivity extends Activity {

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

       public void login(View view){
           EditText id = (EditText) findViewById(R.id.edit1);
           String s = id.getText().toString();
           Intent intent=new Intent();
           intent.setClass(MainActivity.this, TestActivity.class);
           intent.putExtra("id",s);
           startActivity(intent);
       }

}

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class TestActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);
        TextView t = (TextView)findViewById(R.id.text);
        Intent intent = this.getIntent();

        String id = intent.getStringExtra("id");
        System.out.println(intent.getStringExtra("id"));
        t.setText(id);
    }
}

<?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"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text=""></TextView>
    <ImageView
        android:id="@+id/photo"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:src="@drawable/ic_launcher_background"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="200dp"
        android:layout_marginBottom="30dp"></ImageView>
    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/photo"
        android:maxLength="15"
        android:layout_marginTop="13dp"
        android:text="账号："/>
    <EditText
        android:id="@+id/edit1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/photo"
        android:layout_toRightOf="@id/textView1"
        android:hint="请输入您的账号"></EditText>
    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/textView1"
        android:maxLength="20"
        android:layout_marginTop="25dp"
        android:text="密码：" />
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/textView1"
        android:layout_toRightOf="@id/textView2"
        android:layout_marginTop="10dp"
        android:hint="请输入您的密码"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button"
        android:text="登录"
        android:textColor="#478595"
        android:layout_below="@id/textView2"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="120dp"
        android:layout_centerHorizontal="true"
        android:onClick="login">
    </Button>

</RelativeLayout>