写了两个方法（在我理解之中有三个方法，其中循环字符串匹配太low了，pass掉），目前先上传一个，后续补上。。
针对这个问题 总共有四个文件

方法一：正则表达式

（1）MainActivity.java

package com.example.flyyu.four; import android.content.Intent; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.EditText; import android.widget.Toast; import java.util.regex.Pattern; public class MainActivity extends AppCompatActivity implements View.OnClickListener{ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @Override public void onClick(View v) {         EditText a=(EditText)findViewById(R.id.editText);          EditText b=(EditText)findViewById(R.id.editText2);          EditText c=(EditText)findViewById(R.id.editText3);         Intent it=new Intent(this,biapmianji.class); if (!isNumber(a.getText().toString())&&!isNumber(b.getText().toString())&&!isNumber(c.getText().toString())){             it.putExtra("a",a.getText().toString());             it.putExtra("b",b.getText().toString());             it.putExtra("c",c.getText().toString());             MainActivity.this.startActivity(it); } } public boolean isNumber(String s){          String pattern = ".*\D.*"; boolean isMatch = Pattern.matches(pattern,s); if (isMatch||s.length()==0){             Toast.makeText(this,"输入异常",Toast.LENGTH_SHORT).show(); return true; } return isMatch; } } 

2.biapmianji.java

package com.example.flyyu.four; import android.content.Intent; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.TextView; public class biapmianji extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_biapmianji);         TextView textView=(TextView)findViewById(R.id.textView4);         Intent it=this.getIntent(); float a=Float.valueOf(it.getStringExtra("a")) ; float b=Float.valueOf(it.getStringExtra("b")) ; float c=Float.valueOf(it.getStringExtra("c")) ;         String s=(2*(a*b+a*c+b*c))+"";         textView.setText("该长方体的表面积为:"+s); //        textView.setText("该长方体的表面积为:"+a); } } 

3.activity_biapmianji.XML

<?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout xmlns:android="https://schemas.android.com/apk/res/android"     xmlns:app="https://schemas.android.com/apk/res-auto"     xmlns:tools="https://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     tools:context="com.example.flyyu.four.biapmianji"> <TextView         android:id="@+id/textView4"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginBottom="8dp"         android:layout_marginLeft="8dp"         android:layout_marginRight="8dp"         android:layout_marginTop="8dp"         android:text="TextView"         android:textSize="18sp"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintHorizontal_bias="0.174"         app:layout_constraintLeft_toLeftOf="parent"         app:layout_constraintRight_toRightOf="parent"         app:layout_constraintTop_toTopOf="parent"         app:layout_constraintVertical_bias="0.083" /> </android.support.constraint.ConstraintLayout> 

4.activity_main.XML

<?xml version="1.0" encoding="utf-8"?> <!--<android.support.constraint.ConstraintLayout xmlns:android="https://schemas.android.com/apk/res/android"--> <android.widget.LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"     xmlns:app="https://schemas.android.com/apk/res-auto"     xmlns:tools="https://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="vertical"     tools:context="com.example.flyyu.four.MainActivity"> <TextView         android:id="@+id/textView"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_weight="1"         android:text="长：" /> <EditText         android:id="@+id/editText"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_weight="1"         android:ems="10"         android:inputType="text" /> <TextView         android:id="@+id/textView2"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_weight="1"         android:text="宽：" /> <EditText         android:id="@+id/editText2"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_weight="1"         android:ems="10"         android:inputType="text" /> <TextView         android:id="@+id/textView3"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_weight="1"         android:text="高：" /> <EditText         android:id="@+id/editText3"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_weight="1"         android:ems="10"         android:inputType="text" /> <Button         android:id="@+id/button"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_weight="1"         android:onClick="onClick"         android:text="计算" /> </android.widget.LinearLayout>