Activity组件（三）：通过对象实现信息添加及展示

在对组件进行注册时，只注册了EditText，却忘记了Button，导致程序一直闪退

 输入信息

 点击添加

 成功跳转页面，并将数据传递

User.java

package com.example.register;

import android.os.Parcel;
import android.os.Parcelable;

public class User implements Parcelable {
    private String name;
    private  String  age;
    private  String sex;

    public User(String name, String age, String sex) {
        this.name = name;
        this.age = age;
        this.sex = sex;
    }

    public User() {
    }

    //读取
    protected User(Parcel in) {
        name = in.readString();
        age = in.readString();
        sex = in.readString();
    }

    //写入
    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(name);
        dest.writeString(age);
        dest.writeString(sex);
    }

    @Override
    public int describeContents() {
        return 0;
    }

    public static final Creator<User> CREATOR = new Creator<User>() {
        @Override
        public User createFromParcel(Parcel in) {
            return new User(in);
        }

        @Override
        public User[] newArray(int size) {
            return new User[size];
        }
    };

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }
}

UserAddActivity.java

package com.example.register;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import androidx.annotation.Nullable;

public class UserAddActivity extends Activity {
    private EditText mName;
    private EditText mAge;
    private EditText mSex;
    private Button mAddBtn;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_adduser);

        initView();
        initListener();

    }

    private void initListener() {
        mAddBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //添加按钮被点击了
                handlerAdduser();
            }
        });

    }

    private void handlerAdduser() {
        String name = mName.getText().toString().trim();
        if (TextUtils.isEmpty(name)) {
            Toast.makeText(this, "输入的姓名为空", Toast.LENGTH_SHORT).show();
            return;
        }
        String age = mAge.getText().toString().trim();
        if (TextUtils.isEmpty(age)) {
            Toast.makeText(this, "输入的年龄为空", Toast.LENGTH_SHORT).show();
            return;
        }
        String sex = mSex.getText().toString().trim();
        if (TextUtils.isEmpty(sex)) {
            Toast.makeText(this, "输入的性别为空", Toast.LENGTH_SHORT).show();
            return;
        }
        //跳转并传值给AddShowActivity
        Intent intent = new Intent(this, AddShowActivity.class);

        User user = new User();
        //将属性封装到user对象中
        user.setName(name);
        user.setAge(age);
        user.setSex(sex);
        intent.putExtra("userKey",user);
        startActivity(intent);
    }

    private void initView() {
        mName=this.findViewById(R.id.add_name);
        mAge=this.findViewById(R.id.add_age);
        mSex=this.findViewById(R.id.add_sex);
        mAddBtn=this.findViewById(R.id.add_btn);
    }
    
}

activity_adduser.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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:text="添加人员信息"
        android:textSize="30sp"
        android:layout_marginTop="20dp"
        android:layout_gravity="center"
        android:layout_height="wrap_content">

    </TextView>
    <EditText
        android:id="@+id/add_name"
        android:layout_width="match_parent"
        android:text="请输入姓名"
        android:layout_gravity="center"
        android:layout_height="wrap_content">

    </EditText>
    <EditText
        android:id="@+id/add_age"
        android:layout_width="match_parent"
        android:text="请输入年龄"
        android:layout_gravity="center"
        android:layout_height="wrap_content">

    </EditText>
    <EditText
        android:id="@+id/add_sex"
        android:layout_width="match_parent"
        android:text="请输入性别"
        android:layout_gravity="center"
        android:layout_height="wrap_content">

    </EditText>
    <Button
        android:id="@+id/add_btn"
        android:layout_width="wrap_content"
        android:layout_gravity="center"
        android:text="添加"
        android:layout_height="wrap_content">

    </Button>
</LinearLayout>

AddShowActivity.java

package com.example.register;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Parcelable;
import android.widget.TextView;

import androidx.annotation.Nullable;

public class AddShowActivity extends Activity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_addshow);

        TextView nameshow =(TextView) this.findViewById(R.id.add_name_show);
        TextView ageshow =(TextView) this.findViewById(R.id.add_age_show);
        TextView sexshow =(TextView) this.findViewById(R.id.add_sex_show);
        //通过getIntent获取MainActivity传来的intent
        Intent intent = getIntent();
        if (intent!=null) {

            User  user =intent.getParcelableExtra("userKey");
            if (user!=null) {

                nameshow.setText(user.getName());
                ageshow.setText(user.getAge());
                sexshow.setText(user.getSex());
            }
        }
    }
}

activity_addshow.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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:text="添加信息展示"
        android:textSize="30sp"
        android:layout_gravity="center"
        android:layout_height="wrap_content">

    </TextView>


    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:text="姓名"
        android:textSize="20sp"
        android:layout_height="wrap_content">

    </TextView>
        <TextView
            android:id="@+id/add_name_show"
            android:layout_width="wrap_content"
            android:textSize="25sp"
            android:layout_height="wrap_content">

        </TextView>


        <TextView
            android:id="@+id/age"
            android:layout_width="wrap_content"
            android:text="年龄"
            android:textSize="20sp"
            android:layout_height="wrap_content">

        </TextView>
        <TextView
            android:id="@+id/add_age_show"
            android:layout_width="wrap_content"
            android:textSize="25sp"
            android:layout_height="wrap_content">

        </TextView>


        <TextView
            android:id="@+id/sex"
            android:layout_width="wrap_content"
            android:text="性别"
            android:textSize="20sp"
            android:layout_height="wrap_content">

        </TextView>
        <TextView
            android:id="@+id/add_sex_show"
            android:layout_width="wrap_content"
            android:textSize="25sp"
            android:layout_height="wrap_content">

        </TextView>

</LinearLayout>