Android学习04

Toast

Toast是Android系统提供的一种非常好的提示方式,在程序中可以使用它将一些短小的信息通知给用户,这些信息会在一段时间后自动消失,并且不会占用任何的屏幕空间.

1、默认Toast

在屏幕底部显示提示内容

Toast.makeText(getApplicationContext(),"Toast",Toast.LENGTH_LONG).show();

2、使用setGravity()方法来定位Toast 在屏幕上的位置，例如toast.setGravity(Gravity.CENTER, 0, 0)可以把Toast 定位在屏幕中间。

//maleText返回的是toast
Toast toastCenter = Toast.makeText(getApplicationContext(),"ToastCenter",Toast.LENGTH_LONG);
toastCenter.setGravity(Gravity.CENTER,0,0);
toastCenter.show();

3、自定义Toast，图片加文字的形式显示，可以通过增加Toast 的Layout来调整Toast 上的布局方式。增加一个Toast 的Layout描述xml文件，/res/layout/toast_layout.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="#99000000"
    android:gravity="center">

    <LinearLayout
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:orientation="vertical"
        android:gravity="center">

        <ImageView
            android:id="@+id/iv_toast"
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:scaleType="fitCenter"/>

        <TextView
            android:id="@+id/tv_toast"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="20sp"
            android:textColor="#000"
            android:layout_marginTop="15dp"/>
    </LinearLayout>


</LinearLayout>

Toast toastCustom = new Toast(getApplicationContext());
LayoutInflater inflater = LayoutInflater.from(ToastActivity.this);
View view = inflater.inflate(R.layout.layout_toast,null);
ImageView imageView = view.findViewById(R.id.iv_toast);
TextView textView = view.findViewById(R.id.tv_toast);
imageView.setImageResource(R.drawable.icon_lamp);
textView.setText("这是一个灯泡");
toastCustom.setView(view);
toastCustom.show();

完整代码：

layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn_toast1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="默认"/>

    <Button
        android:id="@+id/btn_toast2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="改变位置"/>

    <Button
        android:id="@+id/btn_toast3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="自定义"/>

</LinearLayout>

ToastActivity

package com.example.helloworld;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

public class ToastActivity extends AppCompatActivity {

    private Button mBtnToast1,mBtnToast2,mBtnToast3;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_toast);
        mBtnToast1 = findViewById(R.id.btn_toast1);
        mBtnToast2 = findViewById(R.id.btn_toast2);
        mBtnToast3 = findViewById(R.id.btn_toast3);
        onClick onClick = new onClick();
        mBtnToast1.setOnClickListener(onClick);
        mBtnToast2.setOnClickListener(onClick);
        mBtnToast3.setOnClickListener(onClick);
    }

    class onClick implements View.OnClickListener{
        @Override
        public void onClick(View v) {
            switch (v.getId()){
                case R.id.btn_toast1:
                    Toast.makeText(getApplicationContext(),"Toast",Toast.LENGTH_LONG).show();
                    break;
                case R.id.btn_toast2:
                    //maleText返回的是toast
                    Toast toastCenter = Toast.makeText(getApplicationContext(),"ToastCenter",Toast.LENGTH_LONG);
                    toastCenter.setGravity(Gravity.CENTER,0,0);
                    toastCenter.show();
                    break;
                case R.id.btn_toast3:
                    Toast toastCustom = new Toast(getApplicationContext());
                    LayoutInflater inflater = LayoutInflater.from(ToastActivity.this);
                    View view = inflater.inflate(R.layout.layout_toast,null);
                    ImageView imageView = view.findViewById(R.id.iv_toast);
                    TextView textView = view.findViewById(R.id.tv_toast);
                    imageView.setImageResource(R.drawable.icon_lamp);
                    textView.setText("这是一个灯泡");
                    toastCustom.setView(view);
                    toastCustom.show();
                    break;
            }

        }
    }
}