Android 多个界面(Activity)

1.介绍

2.相关属性

(1)启动Activity

(2)Intent介绍

(3)关闭Activity

3.多个页面之间传递数据(页面1向页面2传递数据，单向传递数据)

(1)相关属性

注意：data为str的代号

(2)xml文件

第一个界面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/tv_weight"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:text="这是标准体重计算界面"
        android:textSize="30dp" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center">

        <TextView
            android:id="@+id/tv_gender"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="请选择性别" />

        <RadioGroup
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="horizontal">

            <RadioButton
                android:id="@+id/radioButton"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="男" />

            <RadioButton
                android:id="@+id/radioButton2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="女" />
        </RadioGroup>

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center">

        <TextView
            android:id="@+id/tv_userheight"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="请输入您的身高" />

        <EditText
            android:id="@+id/et_userheight"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:ems="10"
            android:inputType="textPersonName" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center">

        <Button
            android:id="@+id/bt_calculate"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="计算" />
    </LinearLayout>

</LinearLayout>

第二个界面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:text="这是第二个界面"
        android:textSize="30dp" />

    <Button
        android:id="@+id/bt_goback"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="返回" />

    <EditText
        android:id="@+id/et_message"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPersonName"
        android:text="Name" />

    <EditText
        android:id="@+id/et_weightValue"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPersonName"
        android:text="Name" />
</LinearLayout>

(3)java后台代码

界面1

package com.lucky.test31activity;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;

public class MainActivity extends AppCompatActivity {
    Button bt_calculate;
    EditText et_height;
    RadioButton radioButton;
    String gender;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bt_calculate=findViewById(R.id.bt_calculate);
        et_height=findViewById(R.id.et_userheight);
        radioButton=findViewById(R.id.radioButton);

        bt_calculate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //实现页面之间的跳转
                Intent intent=new Intent(MainActivity.this,SecondActivity.class);
                //若页面之间要传递数据，可以用putExtra()方法，若不需要传递数据则下面两句可以不写
                //toString()一定不能少
                if(radioButton.isChecked()){
                    gender="男";
                }else {
                    gender="女";
                }
                intent.putExtra("003",gender);
                intent.putExtra("004",Integer.parseInt(et_height.getText().toString()));
                startActivity(intent); //进行页面跳转
            }
        });
    }
}

界面2

package com.lucky.test31activity;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class SecondActivity extends AppCompatActivity {
    Button button1;
    EditText et_message;
    EditText et_userweight;
    int userheight;
    double userweight;
    String gender;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        button1=findViewById(R.id.bt_goback);
        et_message=findViewById(R.id.et_message);
        et_userweight=findViewById(R.id.et_weightValue);
        Intent intent=getIntent();//获取Intent
        String name=intent.getStringExtra("001");
        String pwd=intent.getStringExtra("002");
        gender=intent.getStringExtra("003");
        userheight=intent.getIntExtra("004",0);
        if(gender.equals("男")){
            userweight=(userheight-80)*0.7;
        }else {
            userweight=(userheight-70)*0.6;

        }
        et_message.setText("用户名为："+name+"\n密码为："+pwd);
        et_userweight.setText("您的体重为："+userweight);

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();//关闭页面
            }
        });
    }
}

4.页面之间传递数据(页面1与页面2双向传递数据)

(1)介绍

(2) java 后台代码

主界面

package com.lucky.test32activity2;

import android.content.Intent;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {
    EditText page1output;
    EditText frompage2;
    Button button1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        page1output=findViewById(R.id.editText_page1output);
        frompage2=findViewById(R.id.editText_frompage2);
        button1=findViewById(R.id.button_page1);
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent=new Intent(MainActivity.this,page2Activity.class);//实例化intent
                intent.putExtra("001",page1output.getText().toString()); //设置所传递的数据
                startActivityForResult(intent,0x01); //参数2为请求码
            }
        });

    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        //判断请求码与结果码是否一致
        if(requestCode==0x01&&resultCode==0x02){
            frompage2.setText(data.getStringExtra("002"));
        }
    }
}

第二界面

package com.lucky.test32activity2;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class page2Activity extends AppCompatActivity {

    EditText page1input;
    EditText page2return;
    Button button2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_page2);
        page1input=findViewById(R.id.editText_page1input);
        page2return=findViewById(R.id.editText_page2return);
        button2=findViewById(R.id.button_page2);
        final Intent intent=getIntent();
        page1input.setText(intent.getStringExtra("001"));
        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent1=new Intent(); //实例化intent
                intent1.putExtra("002",page2return.getText().toString()); //设置数据,toString()不能省略
                setResult(0x02,intent1); //从第二界面返回第一界面
                finish(); //关闭页面
            }
        });

    }
}

5.效果图

动态1对应工程名：test31,动态2对应工程名：test32